Joint Industry Programme on carbon monoxide issues

HSE
Health & Safety
Executive
Joint Industry Programme on
carbon monoxide issues
Experiments to study the effect of ventilator size
and location on the operation of open-flued gas
boilers when operated within a compartment
Prepared by
Advantica Technologies Limited
(formerly BG Technology)
for the Health and Safety Executive
CONTRACT RESEARCH REPORT
379/2001
HSE
Health & Safety
Executive
Joint Industry Programme on
carbon monoxide issues
Experiments to study the effect of ventilator size
and location on the operation of open-flued gas
boilers when operated within a compartment
J R Lowrie, R W Hill and G Pool
Advantica Technologies Limited
(formerly BG Technology)
Ashby Road
Loughborough
Leicestershire LE11 3GR
United Kingdom
The results are reported of full-scale experiments, carried out at Advantica Technologies Ltd in
Loughborough under controlled conditions, aimed at determining the optimum ventilator configuration
for a natural draught open-flued gas boiler operating within a compartment.
Testing was conducted using different sizes of compartment and three different open-flued boilers to
assess the effect of varying the ventilator arrangement on the process of vitiating the compartment
volume following spillage of combustion products due to insufficient flue pull. The time taken for a boiler
spilling combustion products at a consistent rate to cause a build-up of combustion products, and
consequent reduction in oxygen, in the compartment was measured and taken to be an indication of
how much the ventilation configuration delayed vitiation. Other parameters monitored included the
CO/CO2 ratio and the temperature of the appliance casing.
The specification recommended in BS 5440: part 2: 1989 (Specification for the installation of ventilation
for gas appliances) for ventilating compartments naturally is compared with various ventilation regimes
assessed during the programme.
A major conclusion of the work has been that the ventilation specified in the British Standard probably
represents the most effective means of delaying vitiation caused by a spilling installation. Greater
ventilator areas did not significantly increase the time taken to vitiate and there was evidence to
suggest that to deviate from the recommended split in area between low level and high level (2:1) can
accelerate the vitiation process.
This report and the work it describes were funded by the Health and Safety Executive (HSE). Its
contents, including any opinions and/or conclusions expressed, are those of the authors alone and do
not necessarily reflect HSE policy.
HSE BOOKS
© Crown copyright 2001
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First published 2001
ISBN 0 7176 2120 0
All rights reserved. No part of this publication may be
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ii
CONTENTS
1
2
INTRODUCTION
1
1.1 Background
1.2 Current Study
1
2
EXPERIMENTAL FACILITIES
3
2.1 The Test Chamber
2.2 Gas Appliances
2.3 Experimental Measurements
3
4
5
3
EXPERIMENTAL PROGRAMME
8
4
EXPERIMENTAL PROCEDURE
9
4.1 Outline Procedure
4.2 Detailed Procedure
5
9
9
RESULTS
11
5.1 Potterton Osprey CF150
5.2 Worcester 24Cdi Combi-Boiler
5.3 Myson Apollo 40c Boiler
6
11
13
15
DISCUSSION
17
6.1 Combustion Performance Ratio CO/CO2
6.2 Boiler Casing Temperature
6.3 Ventilation
17
17
17
7
CONCLUSIONS
19
8
RECOMMENDATIONS
20
9
REFERENCES
21
iii
iv
SUMMARY
The results are reported of full-scale experiments, carried out at Advantica Technologies Ltd in
Loughborough under controlled conditions, aimed at determining the optimum ventilator
configuration for a natural draught open-flued gas boiler operating within a compartment.
Testing was conducted using different sizes of compartment and three different open-flued
boilers to assess the effect of varying the ventilator arrangement on the process of vitiating the
compartment volume following spillage of combustion products due to insufficient flue pull.
The time taken for a boiler spilling combustion products at a consistent rate to cause a build-up
of combustion products, and consequent reduction in oxygen, in the compartment was measured
and taken to be an indication of how much the ventilation configuration delayed vitiation. Other
parameters monitored included the CO/CO2 ratio and the temperature of the appliance casing.
The specification recommended in BS 5440: part 2: 1989 (Specification for the installation of
ventilation for gas appliances) for ventilating compartments naturally is compared with various
ventilation regimes assessed during the programme.
A major conclusion of the work has been that the ventilation specified in the British Standard
probably represents the most effective means of delaying vitiation caused by a spilling
installation. Greater ventilator areas did not significantly increase the time taken to vitiate and
there was evidence to suggest that, to deviate from the recommended split in area between low
level and high level (2:1) can accelerate the vitiation process.
v
vi
1 INTRODUCTION
The installation guidelines for open-flued gas appliances operating within a compartment as opposed
to a room are particularly important to ensure that operation is both safe and efficient. In the rare
event of combustion products flowing down the flue and starting to accumulate in a compartment, the
situation can become unsafe more rapidly than if the appliance was room mounted.
It has been with the intention of specifying the best natural ventilation configuration within a
compartment to prevent combustion products from building up that the current study has been carried
out.
1.1
BACKGROUND
Natural draught open-flued domestic gas appliances are designed with a flue break, known as a
draught diverter, local to the appliance which is intended to prevent intermittent downdraught in the
flue (caused perhaps by wind effects around the flue terminal) from directly affecting the appliance
burners. This diverts combustion products away from the combustion chamber and into the room or
compartment where the appliance is located.
Very often, this process lasts for a matter of seconds and does not result in a significant accumulation
of combustion products. However, when, for example, adverse wind conditions persist, build-up can
take place to a significant level particularly when the volume into which spillage occurs is small, as in
the case of a compartment. This has the effect of contaminating or vitiating the combustion air stream
to the appliance and can result in a significant rise in carbon monoxide produced.
Flue gas comprises predominantly carbon dioxide and water vapour with comparatively small
concentrations of carbon monoxide, nitrogen dioxide and nitric oxide (plus unconsumed oxygen, and
nitrogen).
The initial build-up of any spilled combustion products (flue gases) into a room or confined space
such as a compartment therefore causes a rise in carbon dioxide concentration with the water vapour
tending to condense out on cooler surfaces. During this initial phase, the increase in carbon monoxide
concentration is relatively slight. However, once the combustion air supply to the appliance starts to
become affected by carbon dioxide, a process known as vitiation, the combustion process changes and
the rate at which carbon monoxide is produced increases significantly.
It is therefore desirable to ensure that ventilation within the compartment is good enough to delay for
as long as possible any build-up of spilled combustion products and as a result improve the safety of
the installation.
1
1.2
CURRENT STUDY
Whilst current legislation (European Gas Appliance Directive1) requires anti-vitiation devices to be
fitted to new appliances, a substantial population of older appliances currently installed in the UK
(estimated at 40 million in total) are operating without such safety features.
A programme of work has therefore been carried out aimed at identifying whether a preferred
configuration exists for ventilators in a compartment within which an open-flued boiler operates.
Compartment ventilators are intended primarily to ensure an adequate supply of fresh air is available
to maintain efficient flue and appliance performance and also to cool the appliance. However, their
size and location may well be important when combustion products accumulate within the
compartment. In such a situation, the combustion air supply must remain unvitiated for as long as
possible in order to reduce the likelihood of excessive carbon monoxide levels being generated which
may not only build up within but also flow from the compartment (perhaps via the ventilation
openings) and out into the rest of the property.
2
2
EXPERIMENTAL FACILITIES
The test programme employed specially adapted facilities at Advantica in Loughborough using
instrumentation to measure and record various physical parameters. These facilities and the
supplementary instrumentation employed are described below.
2.1
THE TEST CHAMBER
The programme of experiments was carried out using a test chamber adapted to enable appliances to
be installed to standard and flued and for the various comparisons of physical measurements
described in this report to be made. The chamber represented a room within which a compartment
housing a natural draught open-flued boiler was located.
Figure 1 shows a plan drawing of the room layout. For each of the three boilers tested, the room itself
was ventilated via permanent openings which conformed in area to that specified in BS5440: part 2:
19892.
2.1.1
Compartments
Table 1. Compartment sizes
Boiler
Potterton Osprey
CF150
Worcester 24CDi
Myson Apollo
40C
Width
m
1.195
1.789
2.113
Depth
m
1.500
2.236
2.641
Height
m
1.550
2.320
2.740
Volume
m3
2.78
9.28
15.29
Minimum size (Vminosp)
Vminosp * 3.34
Vminosp * 5.5
0.470
0.960
2.08
0.94
More than Vminwor
1.195
1.500
1.550
2.78
Vminwor * 2.96
0.350
0.600
0.801
0.168
1.789
1.500
2.320
6.2
Comment
Minimum size (Vminap), used
for preliminary tests
Vminap * 36.9
For each boiler, the smallest compartment size corresponded to the size of the boiler plus the
minimum clearances (for servicing, etc.) as stated in the manufacturer’s instructions. The larger
compartments for the Potterton Osprey CF150 constituted a scaled up version of the smallest
compartment (ie the aspect ratio was maintained). The larger compartment for the Worcester 24CDi
was the smallest compartment used with the Potterton Osprey CF150 and the larger compartment for
the Myson Apollo 40C was a modified version of one of the larger Potterton Osprey CF150
compartments.
3
The compartments were constructed from plywood and medium density fibreboard (MDF) which was
considered sufficiently dense to prevent any significant flow of air through from outside the
compartment. The panels were fixed in place with respect to each other and the floor using timber
battens and woodscrews. Figure 2 is a photograph of the Potterton Osprey CF150 in the largest
compartment used. The timber battens which can be seen on the back and side walls were used to
locate the panels used in the smaller compartments. (The smallest compartments for the Worcester
24CD boiler and the Myson Apollo 40C wall mounted boiler were too short to reach to floor level,
and were constructed around the boiler.) The interface of the panels with each other and the joints of
the panels with the floor were sealed using either aluminium duct sealing tape or silicone sealant. The
ventilation openings in the compartments were made using a shutter arrangement so that the areas of
opening could be adjusted between tests at both the upper and lower level of the front compartment
panel. Details of the compartment sizes are presented in Table 1.
2.2
GAS APPLIANCES
The experimental programme was designed to provide data on carbon dioxide accumulation and
oxygen depletion resulting from vitiation of the combustion air supply to different models of boiler
under practical (if extreme) conditions. Three boilers were selected to represent the wide range of heat
inputs and draught-diverter designs that exists for domestic use.
The appliances used were a floor standing boiler, a wall-mounted combi-boiler and a wall-mounted
boiler. Each was mounted against the left hand compartment wall (see Figure 1). Details of these are
presented below.
2.2.1
Potterton Osprey CF150
This floor standing domestic central heating boiler has a gross heat input of 53.1kW (181,200 Btu/hr).
It is normally fitted with a thermal down-draught detector (TTB) but for the purposes of this study the
safety device was put out of action.
The flue rose almost vertically out of the chamber through the roof and was then routed close to the
entry of the laboratory air extraction system. A blockage was imposed on the flue using a shutter
arrangement to eclipse part of the cross-sectional area. The differential pressure in the flue was
adjusted so that a level of combustion product spillage was achieved which caused build-up within a
compartment at a readily measurable and consistent rate.
This appliance is photographed within one of the compartments (see Figure 2).
2.2.2
Worcester 24CDi
This wall-mounted combi-boiler has a gross heat input of 30kW (102,370 Btu/hr).
Its flue was blocked using the same method as described for the Potterton Osprey CF150.
The test programme consisted of initially operating the appliance inside the chamber with no
restriction to the air supply, i.e. copious quantities of fresh, uncontaminated air were available to the
burner. The flue pressure was logged as 19µbar, together with the boiler surface and component
temperatures and the CO, CO2 and O2 measured in the secondary flue.
The routing of the flue and methodology employed to ensure combustion product spillage took place
in a consistent way were as described for the Potterton boiler in Section 2.2.1.
The compartment was then constructed around the appliance and sealed, as far as practically possible,
to ensure that air was only available to the boiler through the ventilation openings at the front of the
compartment. The smallest compartment in which the Potterton Osprey boiler was tested, was used as
the largest compartment in which to operate the Worcester 24 CDi.
4
2.2.3
Myson Apollo 40C
This wall-mounted boiler has a maximum heat input of 15.4kW (52,600Btu/hr). The appliance was
fixed to the wall at a height of 0.7m from the floor, with the back of the boiler fixed to the wall.
Once again, the routing of the flue and methodology employed to ensure combustion product spillage
took place in a consistent way were as described for the Potterton boiler in Section 2.2.1.
2.2.4
Operating Arrangements
Each of the three boilers was operated continuously at maximum heat rate by ensuring a constant flow
of cooled water was passing through them. In this way, the water outlet temperature was prevented
from becoming high enough to cause the appliance to turn off or cycle.
2.2.5
Flueing arrangements
Owing to the potentially hazardous nature of the experiments and the operational requirements of the
laboratory, except for flue characterisation tests, combustion products were extracted directly from the
boiler out through the building air extract system. This meant that the boiler flue had to be connected
to this extract system via a length of semi-rigid duct. However, this would have the effect of
producing a much greater flue flow than that produced by using the minimum recommended length of
flue in ‘open air’. The solution was to restrict the flue by means of a horizontal plate at the
intersection of the flue and semi-rigid duct. By varying the protrusion of this plate into the flue, the
flow could be increased or decreased so that a level of combustion product spillage was achieved
which caused build-up within a compartment at a readily measurable and consistent rate.
2.3
EXPERIMENTAL MEASUREMENTS
During each experiment, measurements were made to monitor the concentration of carbon monoxide,
carbon dioxide and oxygen within the compartment, the concentration of carbon monoxide in the flue
gas and the temperatures within the compartment. Details of these measurements are outlined below.
2.3.1
Infrared Analysers
The concentrations of carbon monoxide, carbon dioxide and oxygen were monitored using a Siemens
Ultramat 23 analyser by means of sample probes located in the compartment, inside the boiler, and
inside the flue. The positions used are described in Table 2. The sampling positions were varied from
test to test, and further details are given in the Tables of test details.
The initial tests used 3 probes, located on a stand in the compartment. These were sampled
sequentially using a stream selection unit controlled by an automated data logging/analysis system
and the time between taking successive samples was 45 seconds, which resulted in the time taken to
complete a single sequence of probes to be 2¼ minutes. This cycle time was too long to capture
adequately the speed at which the compartment became vitiated and so the number of sample lines on
the stand was reduced.
Subsequently one sample probe was moved so that it monitored the primary combustion air to the
appliance burner, rather than being located towards the centre line of the compartment.
In addition, the flue gas was sampled in either the primary flue with the probe positioned above the
heat exchanger (Potterton Osprey CF15) or in the secondary flue (Worcester 24CDi and Myson
Apollo 40C ) during most tests. This sample line was used occasionally as an extra compartment
sample line and positioned to provide a representative sample of the combustion products in the flue.
By employing this methodology, samples were taken from the full width of the flue pipe (rather than a
single location) using a multi-hole sample tube. This sample line enabled a continuous and
simultaneous measurement to be made of carbon monoxide, carbon dioxide and oxygen
concentrations. Again, details are given in the Tables of test details.
5
Table 2. Sampling probe positions
Boiler
Probe position and height above floor
Designation
Compartment
0.03m
L (low)
15.29m3
By draught diverter
M (middle)
2.49m
H (high)
Compartment
0.03m
L (low)
9.28m3
2.07m
H (high)
Compartment
0.03m
L (low)
2.78m3
1.30m
Primary flue
0.65m
P
Worcester
24Cdi
By burner air inlet
0.88m
B
Secondary flue
2.15m
S
Myson Apollo
40C
By burner air inlet
0.63m
B
Secondary flue
1.65m
S
Potterton
Osprey CF150
All samples withdrawn during the course of an experiment for analysis were dried using dedicated
Perma Pure drying columns. These columns exchanged water vapour through capillary tubes with
walls made from a semi-permeable membrane and a stream of dry air circulating around them. Such a
technique ensured there was no adsorption of combustion products onto the surface of any solid
drying agents that would otherwise have rendered the resulting gas concentration measurements
inaccurate. Additionally, samples were presented dry to the analyser and did not therefore
compromise the analyser performance.
6
2.3.2
Thermocouples
T-type thermocouples were used to measure the effect on boiler surface and component temperatures
of enclosing the boilers in compartments. These were connected directly to the logging system and
their positions are listed in Table 3.
Table 3
Number
Potterton Osprey CF150
Worcester 24CD
Myson Apollo 40C
1
Front case bottom
Front case centre
Front case centre
2
Top panel, RHS
Front case top, centre
Front case top, centre
3
LHS centre
Ambient air inside controls
section of boiler
Gas valve
4
LHS upper
Gas valve
Boiler case LHS
5
Top panel, LHS
LHS centre
Floor
6
Top panel, centre
LHS upper
Floor
7
Front case centre
RHS centre
Floor
RHS upper
Floor
Floor
Floor
10
Ambient air, centre of
compartment
Compartment wall
11
Compartment wall
Compartment wall
8
9
Front case top, centre
12
13
Compartment wall
14
Compartment wall
2.3.3
Pitot tube and micromanometer
A pitot tube connected to a Furness FC012 Micromanometer was used to measure the differential
pressure in the flue. It was connected directly to the Instrunet data acquisition system to allow direct
monitoring and logging of the flue pressure. Any undue fluctuations in the differential pressure
measurement would mean the spillage of combustion products was not taking place in consistent way
during each comparable test.
The pitot tube was calibrated so that the differential pressure measured could be related to the volume
flow in the flue.
Care should be taken when using the absolute differential pressures to compare flue flow between
tests with the same appliance. They should certainly not be used to compare flow conditions in the
flue during tests carried out with the different boilers.
7
3 EXPERIMENTAL PROGRAMME
The details of the experimental programme are given in Tables 4, 5 and 6. The Tables list tests which
were both conducted to commission the test facility and to set up the experimental arrangement in
addition to those used ultimately to compare and contrast the effect of changing ventilator
configuration upon the tendency to vitiate the compartment.
The experiments were intended to determine:1. The effectiveness of ventilator configuration in dispersing spilled combustion products and
delaying the onset of an unsafe vitiated atmosphere within the compartment. This included
both the rate at which carbon dioxide accumulated and the rate at which oxygen concentration
reduced during a test.
2. The effect upon combustion performance of operating a gas appliance within a compartment,
i.e. any effect on the CO/CO2 ratio.
3. The effect of varying the ventilation configuration upon the appliance surface temperature.
It was intended to study the effect of enclosing the boilers in a ventilated compartment upon boiler
and flue performance parameters. The area of the openings to a compartment was determined by the
minimum recommendations stated in BS5440 part 2. The performance parameters measured at preselected differential pressures were the CO/CO2 ratio measured in the primary or the secondary flue
and the rate of change of the boiler casing temperature.
Initial tests were conducted to measure these parameters when the boiler operated in a plentiful supply
of fresh, uncontaminated air. These tests were followed by installing the boiler in different sizes of
compartment.
The first objective was to measure the composition of combustion air being supplied to the appliance
and how this corresponded with the build up of carbon dioxide (and depletion of oxygen
concentration) within the compartment. Secondly, the influence of ventilator configuration was
assessed for each appliance upon the time taken for an unsafe atmosphere to develop within the
compartment. For each appliance, tests were undertaken in at least two different volumes of
compartment.
In all tests, the appliances were located nearest to the compartment wall furthest from the ventilator
openings. Two sample points were used; one to sample gas from either the primary flue (the probe
positioned immediately above the heat exchanger), or the secondary flue (the probe positioned
centrally and approximately 200mm into the secondary flue), and the other to sample air within the
compartment at the level of the appliance burner. Thermocouples were attached at several positions
on the surface of the boiler to monitor temperature and a Pitot tube (connected to a micromanometer)
was used to detect static/dynamic pressures within the flue.
Testing on the Potterton Osprey boiler had shown that compartment volume alone had no influence on
the appliance and flue performance. Consequently, fewer tests were undertaken with the Worcester
boiler to demonstrate this principle; only a 2.78m3 and a 0.94m3 compartment were used.
8
4 EXPERIMENTAL PROCEDURE
The test programme was conducted to obtain data capable of determining the optimum natural
ventilation regime for a boiler operating in a compartment both to ensure correct operation and to
mitigate the problems associated with spillage within.
The outline procedure adopted and the more detailed methodology employed are presented below.
4.1
OUTLINE PROCEDURE
For each boiler tested, measurements were made using the procedure outlined below.
4.2
i)
The boiler was operated using the minimum length of flue, a plentiful air supply and no
additional extraction of flue products.
ii)
The boiler was set up in the compartment and the flue pull adjusted to provide same as in
free air (in plentiful supply).
iii)
The boiler was set up in compartment with the suction on the flue extract reduced to
provide less flue pull than free air. This ensured that flue products were discharging into
the compartment at a consistent rate so that successive tests could be carried out under
similar spillage conditions. The spillage rate was adjusted so that CO2 build-up and
oxygen depletion within the compartment proceeded in a suitable time scale for
comparisons to be made.
iv)
The above procedure was repeated for each compartment volume used. This ensured any
variation in the ventilation configuration could be assessed using consistent base case
conditions.
DETAILED PROCEDURE
Throughout each experiment, data was, in general, recorded from the time the appliance was ignited
until one of the following conditions had been reached:1. A concentration of greater than 100ppm carbon monoxide was detected outside the
compartment (inside the chamber) by the gas detection system, in which case the automatic
safety shutdown system operated.
2. The appliance burner was extinguished.
3. The concentration of oxygen detected at burner level had reduced by 1.0%.
4. 3 hours had elapsed.
5. Steady-state conditions had been achieved.
9
Prior to the start of each test, the analysers were calibrated and the following procedure followed:a)
Light boiler pilot (for the Potterton Osprey and Myson Apollo boilers. The
b)
Worcester 24CDi did not have a permanent pilot).
c)
Start the flow of water through the boiler.
d)
Check the compartment atmosphere using an analyser to ensure the compartment is clear of
any combustion products.
e)
Adjust compartment ventilator openings to required size. (Any other air gaps in the
compartment walls were sealed).
f)
Close and lock the test chamber door.
Each experiment began with the logging instrumentation running. Each boiler’s main burner was
turned on immediately following the first reading taken by supplying mains electricity to the
appliance. The exception was the Worcester 24Cdi boiler as this required manual ignition.
Any build-up of combustion products then took place with the appliance operating at maximum
power output continuously.
10
5 RESULTS
The details of the test programme carried out are listed in Tables 4, 5 and 6. These tables provide the
details of tests undertaken using the Osprey, Worcester and Apollo boilers respectively. Test data
collected during the programme included:
1. Details of the compartment configuration and general test conditions
2. The change in source carbon monoxide concentration with time
3. Carbon dioxide concentration variation with time close to the location at which combustion air
was drawn into the appliance
4. Oxygen concentration change with time close to location at which combustion air was drawn
into the appliance
Data collected for each installation studied has been interpreted using specific tests for which the
flueing conditions (that is spillage of combustion products) were consistent in order to assess the
influence of varying the ventilation upon the three primary parameters involved (CO/CO2 ratio, time
to vitiate the compartment and boiler surface temperature).
The results obtained are discussed in more detail below. With the considerable number of results
obtained during the programme, the results discussed have been focussed upon both to represent the
patterns or trends observed and also to compare between test sequences where the flue condition was
consistent. This ensures that changes made to ventilation configuration can be justifiably associated
with optimising the way combustion products are cleared when spillage occurs. The atmospheric
composition data has concentrated upon the carbon dioxide build-up and oxygen depletion
measurements. This has been because the production of carbon monoxide is not necessarily a
continuous process, ie its rate of formation can greatly increase once a particular level of CO2 or O2
has been realised. The latter two parameters were therefore used to serve as a better indicator of how
effective ventilation proceeded with time.
5.1
POTTERTON OSPREY CF150
The majority of tests using a particular appliance were carried out using the Osprey boiler. Many of
these tests enabled the sensitivity of varying specific parameters to be determined.
During the early part of the programme, this large domestic floor-standing boiler was operated with
ventilation openings varied from test to test. The heat input of the appliance was such that
significantly greater volumes of combustion products were generated in a given time scale compared
with the other appliances. For this reason, tests were carried out with the flue cross-section blocked
less than the other appliances in order that the rate at which combustion products entered the release
room and then vitiated the compartment volume enabled comparisons to be made for different
configurations of ventilation. The flue blockage was measured with reference to the flue differential
pressure and determined by means of a pitot tube placed in the centre of the flue. The pressure in the
flue when the boiler was operating without any restriction in ventilation was 30µbar. A flue restriction
that resulted in a flue differential pressure of 10µbar was found to impede flue flow out of the
compartment sufficiently in order to vitiate the compartment over a reasonable time period (over a
period of approx 10min to 100min overall).
This restriction was then used for all subsequent tests using the Osprey boiler.
11
In the first instance, the effect of compartment volume and ventilator size/configuration was
considered on three parameters: flue flow (indicated by flue differential pressure); boiler surface and
component temperatures; and combustion quality. However, after several tests had been conducted
according to an initial test programme, it was discovered that neither the boiler surface/component
temperatures, nor the flue flow was greatly influenced by changes in the compartment volume.
5.1.1
Ventilator Configuration
The ventilation between the test chamber and the laboratory area outside was in accordance with that
specified in BS5440: part 2: 1989 to ensure the volume outside the compartment was adequately
ventilated. This involved permanent ventilation openings of area 0.02m2 in the wall of the test
chamber.
Compartment ventilators were sized for this appliance according to BS5440: part2: 1989 and were
0.048m2 at high level and 0.096m2 at low level.
Additional tests were carried out using a semi-rigid ducting between the low level inlet to the 9.28m3
compartment to determine:
a)
b)
whether there was any re-circulation effect without the ducting which enabled CO to reenter the compartment following spillage and removal via the high level vent and
if the use of ducting had any effect upon the time taken to vitiate the combustion air stream
It is known that ducted systems to naturally ventilate compartments are in operation within the
domestic environment and at the moment, these are allowed by BS5440: part2: 1989.
5.1.2
Atmospheric Composition
Figure 3 compares the results of measurements made of oxygen concentration low down (close to
burner level) made using no permanent ventilation openings in different compartment sizes
(volumes). The graph presents the oxygen concentration measured at 0.15m above the floor on the
sample stand as a function of time. This shows that, not unexpectedly, the rate at which oxygen
concentration decreased was in inverse proportion to its volume.
Figure 4 presents the data on oxygen depletion obtained operating the Potterton Osprey CF150 boiler
with different ventilation configurations. Clearly, the rate at which oxygen concentration falls with no
permanent ventilation openings, high level or low level, is greatest. The rate of oxygen depletion with
only a high level ventilator present then tended to be greater than that with only a low level ventilation
opening. With both high and low level ventilators present, it is apparent that the oxygen concentration
fell at a similar rate with those areas present as recommended in the British Standard as those which
exceeded the areas specified. This tends to suggest that in this situation, installation to the Standard
provided a level of ventilation that dealt with spillage of combustion products into the compartment
volume and did not improve noticeably when the areas were increased.
Evidence to support this is presented in Figure 5 where the rate at which oxygen concentration fell in
the 15.29m3 compartment tended to be faster when the high level ventilator area was greater than that
specified in the Standard (with low level area installed to Standard).
Figure 6 shows how the ventilation configuration was seen to affect the time taken for oxygen
concentration to drop in the 9.28m3 compartment. The contrast between the zero ventilator area and
the standard ventilation configuration can be seen clearly and the rate at which oxygen concentration
fell varies little between the Standard configuration and one with equal high and low level areas of
ventilator. An interesting result to note is that when the high level ventilator area was split equally
into two, rather than being in a single opening, then this appeared to increase the rate at which oxygen
concentration decreased, albeit slightly.
12
Figure 7 presents data gathered using the smallest compartment (2.78m3). This suggests that rapid
vitiation took place not only with zero ventilator area, but the process was equally rapid if only high
level ventilators were installed. Only when the upper ventilator area was increased to 0.14m2 did
vitiation start to become delayed. With a ventilator area of 0.14m2 at low level and none at high level,
vitiation proceeded at an even slower rate.
From these results, the preferred ventilator configuration capable of delaying the onset of carbon
monoxide build-up would appear to be when the compartment ventilators were sized according to the
guidelines in BS5440: part 2: 1989, i.e., 18cm2 per kW of appliance maximum rated heat input for a
‘low level’ vent position; and 9cm2 per kW for a ‘high level’ vent position.
Figures 8 and 9 show the way in which a ducted low level inlet to the 9.28m3 compartment affected
the time taken for the oxygen concentration to fall and for carbon monoxide to be produced
respectively when measured at low level in the compartment. It can be seen that the ducted
arrangement appears to be least effective in delaying vitiation despite the inlet area complying to that
recommended in the standard. The rate of production of CO with a ducted inlet only was greatest with
a ducted low level inlet and a correctly configured high level ventilator seemed to improve the
situation only marginally. Indeed, the effectiveness of a low level inlet without ducting (and without a
high level ventilator) was significantly better than either of the ducted ventilator arrangements.
5.1.3
Combustion Performance
Figure 10 shows how measurements made of the combustion performance ratio (CO/CO2) in the
primary flue for different ventilation configurations in the 2.78m3 compartment produced a spread of
results. The data indicated that good performance was maintained best with the British Standard
ventilation present, with other configurations causing combustion quality to be comparatively poor.
5.1.4
Boiler Surface Temperature
Figure 11 illustrates the effect that ventilation configuration had upon boiler casing temperature.
Using the TC1 thermocouple data, the increased rate of rise in temperature observed when operating
with anything less than Standard ventilation can be attributed partly to the boiler working less
efficiently and also to the reduced effectiveness of the ventilation in clearing spilled combustion
products.
5.2
WORCESTER 24CDI COMBI-BOILER
This is a 27kW (net) heat input wall-hung boiler that requires a 1m minimum length of flue for correct
operation. Owing to the constraints of the test chamber, the required length of flue and sufficient
allowance of space for the flue gas ducting, the boiler fixing position had to be 0.4m from the floor of
the compartment. Tests were carried out using the boiler operating in two different volumes of
compartment.
5.2.1
Flue Blockage
The flue was blocked using the same method as that described for the Potterton Osprey CF150. The
test programme consisted of initially operating the appliance inside the chamber with no restriction to
the air supply, i.e., in a plentiful supply of fresh, uncontaminated air. The flue pressure was logged,
together with the boiler surface and component temperatures with the CO, CO2 and O2 measured in
the secondary flue.
13
The compartment was then constructed around the appliance and sealed to ensure combustion air was
only available to the boiler through the ventilation openings at the front of the enclosure.
Compartment 1, the smallest compartment in which the Potterton Osprey boiler was tested, was used
as the largest compartment in which to test the Worcester 24 CDi. Previous testing on the Potterton
Osprey boiler had shown that compartment volume alone had no influence on the appliance and flue
performance. Consequently, fewer tests were undertaken with the Worcester boiler to demonstrate
this principle; only a 2.78m3 and a 0.32m3 compartment volume were used.
5.2.2
Ventilator Configuration
The ventilation between the test chamber and the laboratory area outside was in accordance with that
specified in BS5440: part 2: 1989 to ensure the volume outside the compartment was adequately
ventilated. This involved permanent ventilation openings of area 0.0104m2 in the wall of the test
chamber.
Compartment ventilators were sized for this appliance according to BS5440:part2:1989 and were
0.027m2 at high level and 0.054m2 at low level.
5.2.3
Atmospheric Composition
Figure 12 shows how different ventilator configurations affected the time taken to accumulate
carbon dioxide close to floor level in the 2.78m3 compartment.
It is evident that with no ventilator area present, the accumulation of carbon dioxide took
place most rapidly. With ventilator area configured as recommended by the standard, and
indeed with a total area greater than BS 5440; part2; 1898 specifies, the rate of build-up was
slowest. With only high level ventilator area available, build-up took place slower than with
only low level ventilators present.
Figure 13 presents the variation in oxygen concentration measured close to floor level with
different configurations of ventilation (2.78m3 compartment). Here, a test without low level
ventilation is compared with tests where the ventilation area was split between high and low
level. It can be seen that the variation in high:low level area has a relatively minor effect upon
the time taken to vitiate compared with the situation where no high level ventilator was
present.
Figure 14 shows the way in which oxygen concentration close to floor level varied as a
function of time for a greater range of ventilator configuration in the 2.78m3 compartment.
This trend suggests that with zero ventilator area, the volume vitiated faster than with only a
high level ventilator. This in turn vitiated quicker than with a low level ventilator only with
the greatest delay associated when both high level and low level ventilators were present.
This trend corresponded to that observed when operating the Osprey boiler in the 15.29m3
compartment. Furthermore, the effect of increasing ventilator area above that recommended
in the British Standard was found to have only a marginal effect upon the rate at which
vitiation took place.
In addition, a similar trend was found to that observed with the Osprey boiler in that no
significant reduction in the rate of combustion product accumulation was observed when the
Standard ventilator area was exceeded.
14
5.2.4
Combustion performance
Figure 15 illustrates the effect of varying ventilator configuration upon the combustion performance
as measured using the CO/CO2 ratio. Although the ratio is indicative of good combustion performance
in general (<0.004), the variation in the ratio with time for different configurations demonstrated how
that with only ventilator area present at one level (high or low), the combustion quality reduced
noticeably with time when compared to having both high and low level areas available in the 2.78m3
compartment.
Figure 16 shows how the ventilator configuration affected the combustion performance with time in
the smallest (0.32m3) compartment. Without ventilator area at low level, the deterioration in
combustion performance was markedly greater than that where the ventilation complied with the
British Standard.
Here, as with measurements of atmospheric composition, the poorer the ventilation, the greater the
effect upon the combustion observed with time.
5.2.5
Boiler Casing Temperature
Figure 17 shows how the boiler casing temperature (measured by TC1) rose at a greater rate in the
2.78m3 compartment with only a ventilator available at low level than with ventilator area distributed
evenly between high and low level.
Further evidence of such a temperature rise for different ventilator configurations is shown in Figure
18 where the Standard configuration is seen to have produced the lowest rate of rise in temperature.
5.3
MYSON APOLLO 40C BOILER
5.3.1
Ventilator Configuration
As previously, similar permanent ventilation existed between the chamber and the laboratory.
Compartment ventilators for this appliance were sized according to BS5440: part 2: 1989 as follows:•
Upper vent 0.014m2.
•
Lower vent 0.028m2.
5.3.2
Atmospheric Composition
Figure 19 illustrates the effect of ventilator configuration upon the rate at which oxygen
concentration dropped close to floor level in the 6.2m3 compartment. Ventilator area split
between high and low level was, once again, most effective in reducing the rate at which
oxygen concentration fell. The presence of low level ventilator area appeared to be more
effective in delaying vitiation compared with high level ventilator area only. The test data
suggests that without low level ventilation, vitiation proceeded just as rapidly as when no
ventilator area was present at all.
Figure 20 suggests that the greater the total area available with a 2:1 split low level:high
level, the longer the time taken for vitiation to occur.
For the smallest compartment volume, 0.18m3, the effectiveness of high and low level
ventilator area together is demonstrated with the British Standard configuration again
delaying vitiation for longest (see Figure 21).
15
The British Standard specification was seen to be most effective in delaying vitiation, with
those configurations either involving no ventilator area at all or ventilator area at high level
only appearing to be equally ineffective.
5.3.3
Combustion Performance
The effect of the ventilation configuration upon the combustion performance ratio is
presented in Figure 22 for the 0.18m3 compartment. The least dramatic effect upon CO/CO2
was observed when the ventilator area was as recommended in the British Standard (or,
indeed, a lesser area divided in the same proportions between high and low level).
Data obtained using the 6.2m3 compartment is presented in Figure 23. Here, the combustion
performance in an unventilated compartment deteriorated significantly with time when
compared with that ventilated to the British Standard. With ventilator area only installed at
high level, the combustion ratio increased with time, but less so than in the unventilated
compartment. It can also be seen that the combustion ratio still increased when the boiler
operated with a 2:1 split low:high level but with a smaller total area than that specified in the
standard.
5.3.4
Boiler Casing Temperature
Figures 24 and 25 give information on the temperature increases measured (TC1) when
operating the boiler.
Figure 24 shows how the rise in temperature compared when standard ventilation was
installed compared with a less well ventilated compartment (0.18m3).
The temperature increases measured in the 6.2m3 compartment also reflected the level of
ventilation, although even the Standard ventilation configuration resulted in an appreciable
rise (33C in approximately 30min).
16
6 DISCUSSION
6.1
COMBUSTION PERFORMANCE RATIO CO/CO2
An extensive and comprehensive set of measurements on central heating boilers installed in the home
was conducted by British Gas during the 1980’s3. This was aimed at determining whether the
combustion performance of an appliance could be measured in terms of the carbon monoxide and
carbon dioxide present in the flue gases and whether specific trigger values could be demonstrated to
correspond with acceptable and unacceptable combustion performance from a servicing perspective.
After analysing data collected in the field, it was decided that two trigger values could be justified,
namely 0.004 and 0.008 for the (CO concentration/CO2 concentration).
If a boiler was measured to have a CO/CO2 ratio less than 0.004, then its combustion was deemed to
be good enough to remain until the next annual service without further attention.
A CO/CO2 ratio between 0.004 and 0.008 suggested the boiler should be stripped and cleaned and
then re-measured to ensure its ratio had fallen to below 0.004.
A combustion ratio greater than 0.008 represented an appliance which not only had poor combustion,
but which had a fault requiring rectification. Once corrected, together with a strip and clean, the
appliance would then be re-measured and considered to be operating correctly if the combustion ratio
was below 0.004.
The CO/CO2 parameter therefore represents a proven indicator of combustion quality for open flued
boilers and the measurements made during the current study of boilers in compartments of how this
parameter varied with time following ignition was used to compare the effect of different ventilation
configurations upon boiler performance.
The data obtained from each boiler demonstrated that for ventilation provision below that specified in
the British Standard, the CO/CO2 ratio increased significantly with time compared to that measured
when ventilation was to Standard and above.
6.2
BOILER CASING TEMPERATURE
Measurements of boiler casing temperature were made in order to determine how it was affected by
varying the ventilation configuration.
The performance standard (BS EN 2974) allows there to be a considerable rise in temperature of
appliance casing/components (80K). However, the rise in temperature tends to be inversely
proportional to the effectiveness of ventilation and the data obtained from each boiler has
demonstrated this.
Only when the boiler compartment was small in volume did there appear to be an unrepresentative
rise in temperature and this occurred with the Osprey boiler, that is the highest input rating of those
studied.
6.3
VENTILATION
The British Standard BS5440: part 2: 1989 (Specification for the installation of ventilation for gas
appliances) specifies the installation requirements for the ventilation of new or replacement gas
appliances for domestic or non-domestic purposes utilising 1st, 2nd or 3rd family gases and with a
rated heat input not exceeding 60kW gross.
17
Open flued appliances of heat input less than 7kW gross installed in a room or internal space do not
require a permanent opening to provide air for combustion and correct operation of a suitably sized
flue. Permanent ventilation is, however, required for appliances in excess of 7kW. The available free
ventilator area is 4.5cm2 for every extra kW of appliance heat input rating.
The location of a permanent opening (or openings) within the room or internal space is not specified
and work has been carried out 5 which suggests ventilator location/distribution has no influence on
safe appliance operation.
In contrast, appliances mounted in compartments are required to have both low level and high level
ventilation openings and no 7kW threshold is prescribed in this situation. Here, there is less available
background ventilation than in a room.
Those tests carried out to determine whether a preferred configuration of ventilation exists which may
delay the onset of toxic carbon monoxide build-up when operating a malfunctioning gas appliance
failed to provide conclusive evidence.
Data obtained during the current study (for example as presented in Figure 5) suggested that there was
nothing to be gained with regard to maintaining an unvitiated compartment in providing permanent
ventilation greater than that recommended in the British Standard. In fact, the data tends to support
not only the figures specified in the Standard for total area but also the split in area between low and
high level vent area.
The anomaly in the way an apparently greater total ventilation area was, on occasion, less effective in
maintaining an unvitiated compartment may be due to the way in which combustion air flow to the
appliance could be affected. In the case of a configuration where the ventilation area at low level is
significantly greater than that at high level (as in the British Standard), the appliance has a preferred
flow path to obtain combustion air (path of least resistance). On equalising these areas, the flow of
combustion air is no longer preferred at low level and provides for the possibility of air to be brought
into the compartment through the high level ventilator also. With spillage taking place, this modified
pattern of flow within the compartment can lead to more rapid contamination of the combustion air
stream with a consequent reduction in the time taken to vitiate.
Those results obtained using the Osprey boiler and presented in Figure 5 feature test data where the
higher level ventilator area was greater than that at low level. This, as suggested above, tended to
produce a more rapid depletion in oxygen than for the Standard configuration.
The results obtained using a ducted low level ventilator arrangement rather than ventilator openings
mounted directly onto the compartment wall should give some cause for concern. It is known that
there are a number of domestic systems installed with ducted natural ventilation and the length of duct
involved can extend to several metres.
18
7 CONCLUSIONS
1. The ventilation configurations specified in BS 5440: part 2: 1989 (Ventilation) have proven to
be the most effective in delaying vitiation in different sizes of compartment within which
open-flued boilers have been made to spill combustion products in a controlled manner.
2. The parameters studied, boiler casing temperature, combustion ratio and time to deplete
oxygen within the compartment, each indicated that there was a minimal improvement when
increasing the total ventilator area within the compartment beyond that specified in the British
Standard.
3. The parameters measured suggested that in some cases, to increase high level ventilator area
and make it equal to that available at low level, caused a detrimental effect on the time taken to
vitiate the compartment.
19
8 RECOMMENDATIONS
The following recommendations are based upon the results obtained in the current study.
1. The boilers chosen were considered representative of domestic appliances installed in a UK
home with a different draft diverter in each case and a range of appliance heat inputs included.
However, separate tests may be required to confirm the principles determined during this
study, particularly if an appliance’s draft diverter design was particularly unusual.
2. The collection and analysis of CO incident data related to gas usage is now being undertaken
comprehensively. The number of incidents associated with appliances mounted in
compartments should be monitored to determine whether such installations are figuring
disproportionately.
3. Consideration should be given to how less straightforward ventilation configurations affect the
time taken to vitiate a compartment and whether these have a particular effect upon appliance
performance. The configuration tested in the current study was straightforward in the sense
that ventilators tended to be positioned in the same compartment wall and in the wall opposite
the appliance. Ducted systems in particular require further assessment.
20
9
REFERENCES
1. Council Directive of 29th June 1990 on the approximation of the laws of the member states
relating to appliances burning gaseous fuels (90/396/EEC).
2. Installation and Maintenance of flues and ventilation for gas appliances of rated input not
exceeding 60kw (1st, 2nd and 3rd family gases); BS 5440 ; Part 2 ; 1989.
3. “Servicing – right first time,” by J Newcombe, MD Price and AD Sussex, 126th Annual General
Meeting and Spring Conference of the Institution of Gas Engineers, Bournemouth, 1989, ISSN
0367-7850.
4. BS EN 297 Central Heating Boiler Performance Standard.
5. “Full-Scale Experiments to Study the Effect of Oxygen Depletion and Ventilator Location on the
Production of Carbon Monoxide from Open Flued and Flueless Gas Appliances Operating under
Vitiating Conditions,” by RW Hill and G Pool, HSE Contract Research Report Publication,
HMSO, 1999.
21
ventilators, 0.5m above
floor, and 0.35m from
corners of chamber
Partition wall, from
ceiling
to
0.57m
above floor
0.48m
0.135m
0.16m
3.80m
Back wall of
compartments
Compartments
3.00m
Height of chamber = 2.97m
Figure 1 Plan view of compartment facility
22
Figure 2 Potterton Osprey boiler under test
23
21.5
24
Oxygen Concentration, %v/v
21.0
20.5
15.29m3 Zero Ventilator Area
20.0
9.28m3 Zero Ventilator Area
2.78m3 Zero Ventilator Area
19.5
19.0
18.5
0
500
1000
1500
2000
Time, s
Figure 3 Oxygen depletion as a function of time using the osprey boiler spilling into different volumes of compartment
21.5
25
Oxygen Concentration, %v/v
21
20.5
0m2 low 0m2 high (test2_0704)
0m2 low 0m2 high (test1_0704)
20
0.096m2 low 0.096m2 high (test1_1504)
0.096m2 low 0.048m2 high (test2_1504) - to Standard
0m2 low 0.096m2 high (test1_0804)
19.5
0.048m2 low 0m2 high (test 1_1404)
19
18.5
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
Time, s
3
Figure 4 Oxygen depletion as a function of time for different ventilation configurations (Osprey boiler in 15.29m compartment)
21.2
21
26
Oxygen Concentration, %v/v
20.8
20.6
20.4
0.096m 2 low 0.048m2 high (test1_2004) - to Standard
20.2
0.096m 2 low 0.19m2 high (test1_1904)
20
0.096m 2 low 0.19m2 high (test2_1904)
19.8
0.096m 2 low 0.096m2 high (test1_2104)
19.6
0.096m 2 low 0.096m2 high (test1_1604)
19.4
19.2
19
0
1000
2000
3000
4000
5000
6000
Tim e, s
Figure 5 Oxygen depletion as a function of time for ventilation at and above
3
that specified in the British standard (Osprey boiler in the 15.29m compartment)
21.50
27
Oxygen Concentration, %v/v
21.00
0m 2 low 0m2 high (test1_2804)
20.50
0.096m 2 low 0.048m 2 high (test1_2904) - to Standard
0.096m 2 low 0.096m 2 high - single (test1_3004)
20.00
0.096m 2 low 0.096m 2 high - split (test1_1205)
0.096m 2 low 0.096m 2 high - split (test2_1205)
19.50
19.00
0
1000
2000
3000
4000
5000
6000
7000
Time, s
3
Figure 6 Oxygen depletion as a function of time for different ventilation configurations (Osprey boiler in the 9.28m compartment)
21.50
28
Oxygen Concentration, %v/v
21.00
20.50
0m2 low 0m2 high (test1_1805)
0m2 low 0.048m2 high (test_2_0806)
0m2 low 0.096m2 high (test1_0806)
20.00
0m2 low 0.14m2 high (test3_0806)
0.14m2 low 0m2high (test1_1006)
19.50
19.00
18.50
0
500
1000
1500
2000
2500
3000
Time, s
3
Figure 7 Oxygen depletion as a function of time for different ventilation configurations (Osprey boiler in the 2.78m compartment)
29
Oxygen Concentration, %v/v
21.50
21.00
20.50
test1_0505 - low level only ducted
20.00
test3_1105 - low level only not ducted
19.50
test2_0505 - low level ducted high level 0.048m2
19.00
Low level ventilator area: 0.096 m2
18.50
18.00
0
500
1000
1500
2000
2500
Time, s
Figure 8 Effect of a ducted low level ventilator upon the time taken for oxygen
3
concentration to decrease in the 9.28m compartment (Osprey boiler)
70
30
CO concentration, ppm
60
50
test1_0505 - low level only ducted
40
test3_1105 - low level only not ducted
30
test2_0505 - low level ducted high level 0.048m2
20
Low level ventilator area: 0.096 m2
10
0
0
500
1000
1500
2000
2500
Time, s
3
Figure 9 Effect of a ducted low level ventilator upon the rate of production of CO in the 9.28m compartment (Osprey boiler)
0.03
0.025
0m2 low 0m2 high (test1_1805)
CO/CO2 Ratio
0.02
0.096m2 low 0.048m2 high (test2_1006) - Standard
0.14m2 low 0m2 high (test1_1006)
0.015
0.096m2 low 0.096m2 high (test3_1006)
0.14m2 low 0.072m2 high (test1_1106)
0.01
31
0m2 low 0.048m2 high (test2_0806)
0.005
0
0
500
1000
1500
2000
2500
3000
Time, s
Figure 10 Combustion performance ratio as a function of time for different
3
ventilation configurations (Osprey boiler in the 2.78m compartment)
30.0
29.0
28.0
32
Temperature, C
27.0
0m2 low 0m2 high (test2_0704)
26.0
0m2 low 0.096m2 high (test1_0804)
25.0
0m2 low 0.14m2 high (test1_1304)
24.0
0.96m2 low 0.048m2 high (test2_1504) - to Standard
23.0
0.096m2 low 0.096m2 high (test1_1504)
22.0
21.0
20.0
0
1000
2000
3000
4000
5000
Time, s
Figure 11 Boiler casing temperature (TC1) as a function of time for different
3
ventilation configurations (Osprey boiler in the 15.29m compartment)
3
0.0135m2lower 0m2 high (test2 1607)
33
CO2 Concentration, %v/v
2.5
0.027m2 lower 0m2 high (test4 1607)
0.054m2 low 0m2 high (test3 1607)
2
0.054m2 low 0.027m2 high (test2 1907) - to Standard
0.054m2 low 0.054m2 high (test3 1907)
1.5
0m2 low 0.054m2 high (test1 2007)
0.054m2 low 0.0405m2 high (test3 2007)
1
0m2 low 0.027m2 high
0m2 low 0.0405m2 high
0.5
0m2 low 0m2 high
0
0
500
1000
1500
2000
2500
3000
3500
4000
Time, s
3
Figure 12 CO2 build-up as a function of time for different ventilation configurations (Worcester boiler in 2.78m compartment)
21.5
34
Oxygen Concentration, %v/v
21
20.5
0.054m2 low 0m2 high (test3 1607)
0.054m2 low 0.027m2 high (test3 1907) - to Standard
0.054m2 low 0.054m2 high (test1 1907)
20
0.0135m2 low 0.054m2 high (test4 1907)
0.054m2 low 0.027m2 high (test5 1607)
19.5
19
18.5
0
500
1000
1500
2000
2500
3000
3500
Time, s
3
Figure 13 Oxygen depletion as a function of time for different ventilator configurations (Worcester boiler in 2.78m compartment)
22
35
Oxygen Concentration, %v/v
21
0.0135m2lower 0m2 high (test2 1607)
20
0.027m2 lower 0m2 high (test4 1607)
0.054m2 low 0m2 high (test3 1607)
0.054m2 low 0.027m2 high (test2 1907)
0.054m2 low 0.054m2 high (test3 1907)
19
0m2 low 0.054m2 high (test1 2007)
0.054m2 low 0.0405m2 high (test3 2007)
0m2 low 0.027m2 high (test2 2007)
0m2 low 0.0405m2 high (test1 2107)
18
0m2 low 0m2 high
17
16
0
500
1000
1500
2000
2500
3000
3500
4000
Time, s
3
Figure 14 Oxygen depletion as a function of time for different ventilator configurations (Worcester boiler in 2.78m compartment)
0.0008
0.0007
36
CO/CO2 Ratio
0.0006
0.0135m2lower 0m2 high (test2 1607)
0.027m2 lower 0m2 high (test4 1607)
0.0005
0.054m2 low 0m2 high (test3 1607)
0.054m2 low 0.027m2 high (test2 1907) - to Standard
0.0004
0.054m2 low 0.054m2 high (test3 1907)
0.0003
0m2 low 0.054m2 high (test1 2007)
0.054m2 low 0.0405m2 high (test3 2007)
0.0002
0.0001
0
0
500
1000
1500
2000
2500
3000
3500
4000
Time,s
3
Figure 15 CO/CO2 ratio as a function of time for different ventilation configurations (Worcester boiler in 2.78m compartment)
0.0014
0.0012
CO/CO2 Ratio
0.001
0.0008
0.054m2 low 0.027m2 high (test2 2807) - to Standard
0.0006
0m2 low 0.054m2 high (test1 0208)
37
0.0004
0.0002
0
0
500
1000
1500
2000
2500
3000
3500
4000
4500
Time, s
3
Figure 16 CO/CO2 ratio as a function of time for different ventilation configurations (Worcester boiler in 0.32m compartment)
70.0
60.0
38
Temperature, C
50.0
40.0
0.0135m2lower 0m2 high (test2 1607)
30.0
0.054m2 low 0.054m2 high (test3 1907)
20.0
10.0
0.0
0
500
1000
1500
2000
2500
3000
3500
Time, s
3
Figure 17 Worcester boiler casing temperature (TC1) as a function of time when operating in the 2.78m compartment
70.0
60.0
50.0
39
Temperature, C
0.0135m2lower 0m2 high (test2 1607)
40.0
0.054m2 low 0.027m2 high (test2 1907)
0m2 low 0.054m2 high (test1 2007)
30.0
0m2 low 0m2 high (test1 1607)
20.0
10.0
0.0
0
500
1000
1500
2000
2500
3000
3500
Time, s
3
Figure 18 Boiler casing temperature(TC1) as a function of time with the Worcester boiler operating in the 2.78m compartment
Oxygen Concentration, %v/v
21.5
21
0m2 low 0m2 high (test3 110400)
0m2 low 0.007m2 high (test3 120400)
20.5
0m2 low 0.014m2 high (test2 120400)
0.027m2 low 0.014m2 high (test1 130400) - to Standard
20
0.027m2 low 0m2 high (test1 120400)
40
19.5
19
0
1000
2000
3000
4000
5000
6000
Time, s
3
Figure 19 Oxygen depletion as a function of time for different ventilation configurations (Apollo boiler in 6.2m compartment)
21.2
41
Oxygen Concentration, %v/v
21
20.8
0.014m2 low 0.007m2 high (test1 100400)
20.6
0.027m2 low 0.014m2 high (test1 130400) - to Standard
20.4
20.2
20
0
500
1000
1500
2000
2500
3000
3500
Time, s
3
Figure 20 Oxygen depletion as a function of time for different ventilation configurations (Apollo boiler in 6.2m compartment)
21.5
42
Oxygen Concentration, %v/v
21
20.5
0m2 low 0.007m2 high (test4 1808)
20
0m2 low 0.014m2 high (test5 1808)
0m2 low 0.02m2 high (test6 1808)
19.5
0.007m2 low 0.02m2 high (test7 1808)
0.014m2 low 0.02m2 high (test8 1808) - to Standard
19
18.5
18
0
100
200
300
400
500
600
700
Time, s
3
Figure 21 Oxygen depletion as a function of time for different ventilation configurations (Apollo boiler in 0.18m compartment)
0.06
0.05
CO/CO2 Ratio
0.04
0m2 low 0.007m2 high (test4_1808)
0m2 low 0.02m2 high (test6_1808)
0m2 low 0.014m2 high (test5_1808)
0.03
0.007m2 low 0.007m2 high (test3_1808)
0.014m2 low 0.007m2 high (test2_1808)
0.02m2 low 0.014m2 high (test8_1808) - to Standard
0.02
43
0.01
0
0
100
200
300
400
500
600
700
800
900
Time, s
3
Figure 22 CO/CO2 ratio as a function of time for different ventilation configurations (Apollo boiler in 0.18m compartment)
0.02
0.018
0.016
CO/CO2 Ratio
0.014
0m2 low 0m2 high (test3_110400)
0.012
0.027m2 low 0.014m2 high (test1_130400) - to Standard
0.01
0m2 low 0.014m2 high (test2_120400)
0.008
44
0.007m3 low 0.003m2 high (test1_110400)
0.006
0.004
0.002
0
0
1000
2000
3000
4000
5000
6000
Time, s
3
Figure 23 CO/CO2 ratio as a function of time for different ventilation configurations (Apollo boiler in 6.2m compartment)
50.0
45
Temperature, C
40.0
0m2 low 0.007m2 high (test4 1808)
30.0
0.014m2 low 0.02m2 high (test8 1808) - to
Standard
20.0
10.0
0
50
100
150
200
250
300
350
400
450
Time, s
3
Figure 24 Apollo boiler casing temperature (TC1) as a function of time when operating in the 0.18m compartment
70.0
46
Temperature, C
60.0
0m2 low 0m2 high (test3 110400)
50.0
0.027m2 low 0.014m2 high (test1 130400) - to Standard
40.0
0.027m2 low 0m2 high (test1 120400)
30.0
20.0
0
1000
2000
3000
4000
5000
6000
Time, s
3
Figure 25 Boiler casing temperature (TC1) of the Apollo boiler when operating in the 6.2m compartment
Table 4 Osprey boiler test programme details (part 1 of 8)
Upper
Upper vent, Boiler Flue
Lower
dP
Vent distance flue
Vent Size
Size from probe
m2
?
Pa
m2 ceiling
(m)
47
Test
Filename
Comp
Vol m3
test1_1202
15.29
N/A
N/A
N/A
Y
3.0
Initial test to check logging system function
test1 1502
test1_1602
15.29
15.29
N/A
N/A
N/A
N/A
N/A
N/A
Y
Y
3.0
N/A
Initial test to check analyser outputs
Checking program function
test1_1702
15.29
N/A
N/A
N/A
Y
N/A
Checking program function
test1_1802
test1_1902
15.29
15.29
N/A
N/A
N/A
N/A
N/A
N/A
Y
Y
3.0
N/A
Checking response of analyser to cycle time
Checking program function
test1_0303
15.29
0.43
Y
3.0
Confirmation of correct program function
test1_0503
15.29
0
0
N/A
Y
2.7
test2_0503
15.29
0
0
N/A
Y
1.0
test1_0803
15.29
0.0956 0.0478
0.43
Y
1.0
test2_0803
15.29
0.0956 0.0478
0.43
Y
1.5
test1_0903
15.29
0
0
N/A
Y
1.5
test1_1503
15.29
0
0
N/A
Y
1.5
0.0956 0.0478
Comments
Flue rendered less effective and vents closed. Test intended to measure rapidity
of vitiation; flue pull caused ingress of air to compartment - test terminated.
Flue restricted further. Test intended to measure rapidity of vitiation. TTB
caused NVLO - test terminated.
Vents opened to BS5440:2 1989 minimum recommendations for 53.1 kW gross
heat input boiler (47.8 kW net).TTB caused NVLO - subseq. disabled
Test to quantify effect (on compartment air quality, boiler surface/componment
temperatures and combustion) of reducing flue effectiveness. Test terminated
when CO contamination of compartment air only reached 17ppm measured at
room cntre after two hours of boiler operating at maximum rate.
As above, but with zero ventiilation area to compartment. Unexpected primary
flue readings; test repeated (test1_1503)
(See above)
Table 4 Osprey boiler test programme details (part 2 of 8)
Upper
Upper vent, Boiler Flue
Lower
dP
Vent distance flue
Vent Size
Size from probe
m2
?
Pa
m2 ceiling
(m)
48
Test
Filename
Comp
Vol m3
test2_1503
15.29
0
0
N/A
Y
1.0
test1_1703
15.29
0
0
N/A
N
0.2
test1_1903
15.29
0.0956 0.0478
0.43
N
0.2
test2_1903
15.29
0.0717 0.0717
0.43
N
0.2
test1_2303
15.29
1
0.18
0.43
N
0.2
test2_2303
15.29
1
0.18
0.43
N
0.2
As above, but with flue restricted further to hasten effect on measured
parameters. 39ppm CO reached in room centre after 24 minutes of boiler
operating at max.
Flue rendered (almost) ineffective; vents closed. Test measured rapidity of
vitiation for compartment 5. Contamination of compartment air now measured at
3 points (0.1m from floor; room centre; and .25m from ceiling).
Vent. Areas recommended in BS5440:2 1989
Lower vent area reduced; upper vent area increased; total area remains equivalent
to BS5440:2 1989 minimum recommendations.
Effect (on vitiation time) of vent areas in excess of BS5440:2 1989 minimum
recommendations. Test aborted; repeated - test2_2303
(See above)
test1_2603
15.29
0.095
0.095
0.43
N
0.2
Vent areas recommended in 1998 draft revision
test2_2603
15.29
0
0
N/A
N
0.2
3 point room sample data for vitiation.
test1_3003
15.29
0.0956
0.095
0.1
N
test2_3003
15.29
0.0956
0.191
0.1
N
test1_3103
15.29
0.191
0.191
0.1
N
test2_3103
15.29
0.0717 0.0717
0.43
N
Comments
Test to quantify effect (on vitiation time) of raising upper vent position to highest
possible level within compartment. Vent areas as per 1998 draft revision.
As above, plus increasing upper vent size to double 1998 draft recommended
0.2
size.
As above, plus increasing lower vent size to double 1998 draft recommended
0.2
size.
Test repeated (originally test2_1903). Original results were inconsistent with
0.2
those from other tests using both larger total vent area and zero vent area.
0.2
Table 4 Osprey boiler test programme details (part 3 of 8)
Upper
Upper vent, Boiler Flue
Lower
dP
Vent distance flue
Vent Size
Size from probe
2
m
?
Pa
m2 ceiling
(m)
49
Test
Filename
Comp
Vol m3
test1_0604
15.29
0
0
N/A
N
1.9
test2_0604
15.29
0
0
N/A
N
1.5
test1_0704
15.29
0
0
N/A
N
1.0
test2_0704
15.29
0
0
N/A
N
1.0
Repeat of test1_0704. 1.0% floor level CO2 contamination reached in 1170 sec.
test1_0804
test2_0804
15.29
15.29
0
0
0.0956
0.19
0.43
0.43
N
N
1.0
1.0
1.0% floor-level CO2 contamination reached at 1400 seconds after boiler on.
1.0% floor-level CO2 contamination reached at 3550 seconds after boiler on.
test1_1304
15.29
0
0.14
0.43
N
1.0
1.0% floor-level CO2 contamination reached at 2650 seconds after boiler on.
test2_1304
15.29
0.0956
0
N/A
N
1.0
1.0% floor-level CO2 contamination reached at 4250 seconds after boiler on
test1_1404
15.29
0.048
0
N/A
N
1.0
1.0% floor-level CO2 contamination reached at 2451 seconds after boiler on.
Comments
Test to quantify time taken to reach 0.5% CO2 measured at floor. Initial test to
determine flue dP necessary to reach this. Test terminated when steady state
reached at 0.04% CO2 at floor.
As above; reduced flue pull. Test terminated as steady state reached at very low
CO2 concentration at floor level.
As above. 1.0% floor-level CO2 contamination reached at 1170 seconds after
boiler switched on.
Table 4 Osprey boiler test programme details (part 4 of 8)
Upper
Upper vent, Boiler Flue
Lower
dP
Vent distance flue
Vent Size
Size from probe
m2
?
Pa
m2 ceiling
(m)
50
Test
Filename
Comp
Vol m3
test1_1504
15.29
0.096
0.096
0.43
N
1.0
1.0% floor-level CO2 contamination reached at 4401 seconds after boiler on.
test2_1504
test1_1604
15.29
15.29
0.096
0.096
0.048
0.096
0.43
0.1
N
N
1.0
1.0
test1_1904
15.29
0.096
0.19
0.1
N
1.0
test2_1904
15.29
0.096
0.19
0.1
N
1.0
test1_2004
15.29
0.096
0.048
0.1
N
1.0
1.0% floor-level CO2 contamination reached at 4051 seconds after boiler on.
1.0% floor-level CO2 contamination reached at 3951 seconds after boiler on.
1.0% floor-level CO2 contamination reached at 3401 seconds after boiler on.
This result is inconsistent with previous result. Re-test (see test2_1904)
1.0% floor-level CO2 contamination reached at 3901 seconds after boiler on.
Retest (see above)
1.0% floor_level CO2 contamination reached at 4851 seconds after boiler on.
test2_2004
15.29
0.048
0.048
0.1
N
1.0
1.0% floor-level CO2 contamination reached at 4806 seconds after boiler on.
test1_2104
15.29
0.096
0.096
0.1
N
1.0
Repeat of test1_1604.
test1_2204
15.29
0.096
0.096
0.1
N
1.0
Door to chamber open. Test terminated when CO2 concentration remained at
0.10% for 30 mins.
Comments
Table 4 Osprey boiler test programme details (part 5 of 8)
Upper
Upper vent, Boiler Flue
Lower
dP
Vent distance flue
Vent Size
Size from probe
m2
?
Pa
m2 ceiling
(m)
51
Test
Filename
Comp
Vol m3
test2_2204
15.29
0.048
0.048
0.1
N
1.0
test1_2304
test2_2304
15.29
15.29
0
0
0.048
0.19
0.1
0.1
N
N
1.0
1.0
Door to chamber open. Vents blocked when CO2 concentration remained below
0.25% for over 20 mins.
1.0% floor-level CO2 contamination reached at 1200 seconds after boiler on.
1.0% floor-level CO2 contamination reached at 1500 seconds after boiler on.
test1_2604
15.29
0
0.14
0.1
N
1.0
1.0% floor-level CO2 contamination reached at 1800 seconds after boiler on.
test1_2804
9.28
0
0
N/A
N
1.0
test1_2904
9.28
0.096
0.048
0.05
N
1.0
Compartment volume reduced to 60% of previous. 1.0% floor level CO2
concentration reached after 653 seconds.
1.0% floor level CO2 concentration reached after 5430 seconds.
test2_2904
9.28
0.096
0.096
0.05
N
1.0
1.0% floor level CO2 concentration reached after 5180 seconds.
test1_3004
9.28
0.096
0.096
0.05
N
1.0
test1_0405
9.28
0.096
0.096
0.05
N
Comments
Upper vent in horizontal orientation. 1.0% floor level CO2 concentration reached
at 5020 seconds.
Upper vent in horizontal orientation. 1.0% floor level CO2 concentration reached
1.0
at 4160 seconds.
Table 4 Osprey boiler test programme details (part 6 of 8)
Upper
Upper vent, Boiler Flue
Lower
dP
Vent distance flue
Vent Size
Size from probe
m2
?
Pa
m2 ceiling
(m)
52
Test
Filename
Comp
Vol m3
test1_0505
9.28
0.096*
0
N/A
N
1.0
test2_0505
9.28
0.096*
0.048
0.05
N
1.0
test1_0705
9.28
0.096
0.072
0.05
N
1.0
*Lower vent connected via semi rigid duct to exterior vent (in chamber wall)
preventing direct ingress of contaminated room air into compartment. Upper
vent closed. 1.0% @ floor - 1060 sec.
*As above. Upper vent opened to 0.048m2, horizontal orientation; 1.0% @ floor
- 2000 sec.
Upper vent horizontal. 1.0% @ floor - 4540 seconds
test1_1005
9.28
0.096
0.024
0.05
N
1.0
Upper vent horizontal. 1.0% @ floor - 5680 seconds
test2_1005
9.28
0.096
0.048
0.05
N
1.0
test1_1105
9.28
0.096
0.096
0.05
N
1.0
test2_1105
9.28
0.096
0.12
0.05
N
1.0
test3_1105
9.28
0.096
0
N/A
Primary 1.0
test1_1205
9.28
0.096
0.096
N/A
Primary 1.0
Comments
Upper vent horizontal. 1.0% @ floor - not reached before test terminated (CO
contamination of chamber air having reached 100ppm). However, CO2 reached
0.93%; time to 1.0% estimated to be approximately 6200 seconds.
Upper vent horizontal. 1.0% @ floor - 4640 seconds.
Upper vent horizontal. 1.0% @ floor - not reached before test terminated (CO
contamination of chamber air having reached 100ppm). However, CO2 reached
0.96%; time to 1.0% estimated to be approximately 5000 seconds.
Primary flue CO2 measurement reached the maximum measurable by the
analyser (10.5%) within a few minutes. Hence no accurate CO/CO2 ratio
measurements possible; ? need to measure secondary flue gases.
Upper vent area split into 2 x 0.048m2 vents. Test terminated when floor-level O2
depleted by 1.0%. Primary flue CO2 did not exceed max. measurable by
analyser.
Table 4 Osprey boiler test programme details (part 7 of 8)
Upper
Upper vent, Boiler Flue
Lower
dP
Vent distance flue
Vent Size
Size from probe
m2
?
Pa
m2 ceiling
(m)
Comp
Vol m3
test2_1205
9.28
0.096
0.096
N/A
test1_1805
test1_0806
2.78
2.78
0
0
0
0.096
N/A
0.05
Upper vent area split into 2 x 0.048m2 vents. Test terminated when floor-level O2
depleted by 1.0%. (Repeat of previous test to verify results).
Primary 1.0
New compartment volume (2.78m3). Zero Ventilation
Primary 1.0
Upper vent open only
test2_0806
2.78
0
0.048
0.05
Primary 1.0
test3_0806
2.78
0
0.14
0.05
Primary 1.0
test1_0906
2.78
0.048
0
N/A
test2_0906
2.78
0.096
0
N/A
53
Test
Filename
Comments
Primary 1.0
Upper vent open only
Upper vent open only
Low er vent open only. Time to 1.0% floor level CO2 concentration not recorded
Primary 1.0
(>2500 seconds). Boiler cycled or analyser re-started...
Lower vent open only. Time to 1.0% floor level CO2 concentration not recorded
Primary 1.0
(>3000 seconds).
Table 4 Osprey boiler test programme details (part 8 of 8)
Upper
Upper vent, Boiler Flue
Lower
dP
Vent distance flue
Vent Size
Size from probe
m2
?
Pa
m2 ceiling
(m)
Test
Filename
Comp
Vol m3
test1_1006
2.78
0.14
0
N/A
Primary 1.0
test2_1006
2.78
0.096
0.048
N/A
Primary 1.0
test3_1006
2.78
0.096
0.096
N/A
Primary 1.0
test4_1006
2.78
0.14
0.072
N/A
Primary 1.0
test1_1106
2.78
0.14
0.072
N/A
Primary 1.0
Comments
Lower vent open only. Time to 1.0% floor level CO2 concentration not recorded
(>>3000 seconds).
Both vents open to BS5440 part 2 recommendations. Time to 1.0% floor-level
CO2 contamination not recorded (>>3000 seconds).
Time to 1.0% floor-level CO2 contamination not recorded (>3000 seconds).
Vent sizes each increased by 50% on current BS5440 recommendations. Time to
1.0% floor-level CO2 contamination not recorded (>3000 seconds).
Repeat of test4_1006.
54
Table 5 Worcester Boiler Test Programme Details (part 1 of 4)
Test
Filename
Comp
Vol m3
Upper
Flue
Upper vent,
Lower
Boiler
dP
Vent distance
Vent Size
flue
Size from
m2
probe ?
Pa
m2 ceiling
(m)
N/A
N/A
N/A
N/A
Secondary 18
test1_0707
N/A
N/A
N/A
N/A
Secondary 19
test1_1307
2.78
N/A
N/A
N/A
Secondary 19
test2_1307
2.78
0
0
N/A
Secondary 17
test1_1407
2.78
N/A
N/A
N/A
Secondary 17-22
test2_1407
2.78
0
0
N/A
Secondary 17
test3_1407
2.78
0.0135
0
N/A
Secondary 18
55
test1_0607
Comments
Boiler operated with chamber door open and extraction duct disconnected from
flue. The minimum length of flue for this boiler (1m) was connected.
Secondary flue probe 100mm from top of flue. Pitot tube positioned in centre
of flue just upstream of gas analyser probe. Door to chamber closed at 1280
seconds after test start; no discernable effect on flue pressure (remained at
18lbar).
As above; test continued with chamber door open until temperatures started to
reach steady state. Flue pressure seem to remain at 0.019mbar for much of the
time; this was slightly higher than that recorded in test1_0607.
Duct connected to flue outlet; front of compartment left open; chamber door
closed.
Duct connected to flue outlet; front of compartment sealed, i.e., zero
ventilation. Flue pressure reduced slightly as a result.
Flue pressure adjusted using duct restrictor, to try to reproduce similar CO, CO2
and O2 values measured in test 75 (above). At 0.019mbar (using duct with
induced draught) CO2 higher and O2 lower than 0.019mbar natural draught
indicating insufficient air dilution in secondary flue (compared with natural
draught). Similar concentrations achieved (using duct) at 0.022mbar. Despite
previous experience, use of pitot tube would now appear an unreliable way of
ensuring repeatability.
Flue pressure reduced to 17 lbar by reduced pressure inside compartment? CO2
contamination of compartment air only reached 0.1%.
Lower vent only open to (0.0135m2) one quarter BS5440:2 recommendation
(0.054m2)
Table 5 Worcester Boiler Test Programme Details (part 2 of 4)
Test
Filename
Comp
Vol m3
Upper
Flue
Upper vent,
Lower
Boiler
dP
Vent distance
Vent Size
flue
Size from
2
m
probe ?
Pa
m2 ceiling
(m)
Comments
56
test4_1407
2.78
0.054
0
N/A
Secondary 18
test1_1507
2.78
0.054
0.0135
N/A
Secondary 18
test2_1507
2.78
0
0
N/A
Secondary
3
Lower vent only open to BS5440:2 recommendation (0.054m2). Combustion air
remained the same as for 0.0135m2 vent (0.04% CO2), ie, lower vent size alone
appeared to influence neither boiler performance nor flue flow.
Upper vent also open (to 0.0135m2). No change from previous test results. Necessary
to further restrict flue duct in order to observe any vitiation within the compartment.
Vents closed; flue pressure 3ubar initially, rises to 3 - 4ubar during test.
test3_1507
2.78
0
0
N/A
Secondary
6
Vents closed; flue pressure 5ubar initially, rises to 6ubar during test.
test1_1607
2.78
0
0
N/A
Secondary
6
test2_1607
2.78
0.0135
0
N/A
Secondary
8
test3_1607
2.78
0.054
0
N/A
Secondary
8
test4_1607
2.78
0.027
0
N/A
Secondary
8
test5_1607
2.78
0.054
0.0135
N/A
Secondary
8
test1_1907
2.78
0.054
0.0135
N/A
Secondary
8
test2_1907
2.78
0.054
0.027
N/A
Secondary
9
test3_1907
2.78
0.054
0.054
N/A
Secondary
9
Vents closed; flue pressure 5ubar initially, rises to 6ubar during test. Swapped
analysers over to achieve improved measurement of compartment air CO
concentration.
Flue restriction unchanged from previous tests; increase to 8ubar resulting from
opening lower vent.
Lower vent opened to 0.054m2. CO2 concentration in compartment air peaked at 1.2 1.3 % then declined to 1.0%.
Lower vent 0.027; upper vent closed
Lower vent 0.054; upper vent 0.0135. Test discontinued before 1.0% CO2
concentration reached.
Repeat of test5_1607; test continued to assess time taken to accumulate 1.0% CO2
concentration inside compartment.
Ventilation complying with BS5440:2 for this size of boiler. With upper vent open to
0.027m2, flue pressure increased to 9ubar.
Although upper vent open to twice that in previous test, times to 1.0% O2 depletion and
1.0% CO2 concentration were identical in the two tests (allowing for accuracy of
analysers).
Table 5 Worcester Boiler Test Programme Details (part 3 of 4)
Test
Filename
Comp
Vol m3
Upper
Flue
Upper vent,
Lower
Boiler
dP
Vent distance
Vent Size
flue
Size from
m2
probe ?
Pa
m2 ceiling
(m)
57
test1_2007
2.78
0
0.054
N/A
Secondary
8
test2_2007
2.78
0
0.027
N/A
Secondary
8
test3_2007
2.78
0.054
0.0405
N/A
Secondary
9
test1_2107
2.78
0
0.0405
N/A
Secondary
8
test2_2107
2.78
0.0405
0
N/A
Secondary
Upper vent only open to 0.054m2; flue pressure reduced to 8ubar.
Compartment air becomes more rapidly contaminated than in previous tests
with greater total vent area.
Upper vent only open to 0.027m2.
Times to reach 1.0% O2 depletion and 1.0% CO2 concentration were greater
than test3_1907, even though upper vent (and total vent) area was less. This
follows the pattern of data from similar experiments with Potterton Osprey.
Similar results to test1_2007. Flue pressure reduced to 8ubar.
Vents closed. Flue pressure reduced to 5ubar; vitiation measurable from
secondary flue within 3minutes. However, CO2 and O2 concentrations in the
compartment air remained level even though CO increased beyond range
measurable by analysers.
CO remained within measurable range for duration of test. CO2 concentration
increased and O2 concentration decreased as expected.
test1_2607
0.32
0
0
N/A
Secondary
test2_2607
0.32
0
0.0135
0.2
Secondary
test3_2607
0.32
0
0.027
As above.
test4_2607
0.32
0
0.0405
As above.
test1_2707
0.32
0
0.054
0.2
Secondary
5
Comments
9
O2 concentration reduced to below 20% very soon after boiler reaches higher
rate.
Table 5 Worcester Boiler Test Programme Details (part 4 of 4)
Upper
Flue
Upper vent,
Lower
Boiler
dP
Vent distance
Vent Size
flue
Size from
m2
probe ?
Pa
m2 ceiling
(m)
58
Test
Filename
Comp
Vol m3
test2_2707
0.32
0.0135
0
N/A
Secondary
9
test3_2707
test1_2807
0.32
0.32
0.027
0.054
0
0.0135
N/A
0.2
Secondary
Secondary
9
9
test2_2807
0.32
0.054
0.027
0.2
Secondary
9
test1_2907
0.32
0.054
0.0405
0.2
Secondary
9
test2_2907
0.32
0.054
0.054
0.2
Secondary
9
test1_3007
0.32
0.054
0
N/A
Secondary
9
test1_0208
0.32
0
0.054
0.2
Secondary
8
Comments
O2 concentration reduced to below 20% very soon after boiler reaches higher
rate, but returns to 20.9% after a short time. Test terminated as CO2 not
increasing; O2 not decreasing.
CO2 concentration increases (and O2 depletes) more quickly with larger upper
vent size. Why ?
As above.
CO2 concentration increase - consistent with previous two test results. O2
depletion - not consistent.
Test terminated when compartment CO2 concentration did not increase beyond
0.15% after over 1.5 hours (O2 20.65% at this time).
Repeat of test1_2707 - confirms results.
Table 6 Apollo Boiler Test Programme Details (part 1 of 3)
Test
Filename
Comp
Vol m3
Upper
Flue
Upper vent,
Lower
Boiler
dP
Vent distance
Vent Size
flue
Size from
m2
probe ?
Pa
m2 ceiling
(m)
Secondary
Comments
59
Boiler operated with chamber door open and extraction duct disconnected from flue.
The minimum length of flue according to BS5440: part 1: 1989 (0.6m) was connected.
Secondary flue probe 100mm from top of flue. Pitot tube positioned in centre of flue
just upstream of gas analyser probe.
Flue duct not connected. However, air within compartment starts to become vitiated in
a reasonable time even without reducing the effectiveness of the flue. Test terminated
before 1.0% compartment air CO2 contamination reached because chamber air
becoming contaminated with CO.
Test terminated: compartment O2 concentration did not decline.
Duct blockage increased to to greatest possible in order to reduce flue pressure.
Compartment O2 concetration declined to 20.58 over 40 mins. Test terminated.
As above; allowed test to continue until O2 depleted by 1.0%.
Upper vent sealed. CO2 increase and O2 depletion fairly rapid, then reversed. CO2
reached peak of 0.66% after 500 seconds and thereafter reduced to 0.3%. O2 reached
1.0% depletion after only 440 seconds then O2 increased to 20.3%. However, vitiation
is occurring; CO in secondary flue climbs steadily to 1000ppm over the duration of
test.
test1_0908
N/A
N/A
N/A
0
test1_1008
0.18
0.014
0.014
0.2
Secondary 16
test2_1008
0.18
0.027
0.027
0.2
Secondary 16
test3_1008
0.18
0.027
0.027
0.2
Secondary 11
test1_1608
0.18
0.027
0.027
0.2
Secondary 11
test2_1608
0.18
0.027
0
0.2
Secondary 11
test3_1608
0.18
0.014
0
0.2
Secondary 11
test1_1708
0.18
0.007
0
0.2
Secondary 11
1.0% O2 depletion reached in 180 seconds, then reversed slightly (as in test2_1608).
test2_1708
0.18
0.007
0.027
0.2
Secondary 11
Did not reach 1.0% O2 depletion
test3_1708
0.18
0
0.027
0.2
Secondary 11
test4_1708
0.18
0.007
0
0.2
Secondary
9
O2 depleted by 1.0% in 100 seconds. CO2 did not reach 1.0% concentration inside
compartment. Conclusion: flue flow too great to produce build-up of CO2 inside
compartment.
Flue duct blocked further (second flue duct restrictor added). Vitiation occurs more
rapidly.
Table 6 Apollo Boiler Test Programme Details (part 2 of 3)
Upper
Flue
Upper vent,
Lower
Boiler
dP
Vent distance
Vent Size
flue
Size from
2
m
probe ?
Pa
m2 ceiling
(m)
60
Test
Filename
Comp
Vol m3
test5_1708
0.18
0.014
0
0.2
Secondary
9
test6_1708
test7_1708
0.18
0.18
0.02
0.027
0
0
0.2
0.2
Secondary
Secondary
9
9
test8_1708
0.18
0.027
0.007
0.2
Secondary
9
O2 did not deplete by 1.0%; CO2 concentration did not increase to 1.0%.
test1_1808
test2_1808
0.18
0.18
0.02
0.014
0.007
0.007
0.2
0.2
Secondary
Secondary
9
9
O2 did not deplete by 1.0%; CO2 concentration did not increase to 1.0%.
O2 did not deplete by 1.0%; CO2 concentration did not increase to 1.0%.
test3_1808
0.18
0.007
0.007
0.2
Secondary
8
Decrease in ventilator area caused reduction in flue pressure.
test4_1808
0.18
0
0.007
0.2
Secondary
8
test5_1808
0.18
0
0.014
0.2
Secondary
8
test6_1808
0.18
0
0.02
0.2
Secondary
8
test7_1808
0.18
0.007
0.02
0.2
Secondary
8
test8_1808
0.18
0.014
0.02
0.2
Secondary
9
test1_1908
0.18
0.014
0.02
0.2
Secondary
8
test2_1908
0.18
0.014
0.014
0.2
Secondary
8
Comments
Increased flue pressure results from increased ventilator area. Otherwise, as
test 128.
Flue duct blockage level increased - flue pressure reduced to 5µbar (initially)
rising to 8µbar when operating temperature was reached. O2 did not deplete by
1.0%; CO2 concentration did not reach 1.0%.
As above.
Table 6 Apollo Boiler Test Programme Details (part 3 of 3)
Upper
Flue
Upper vent,
Lower
Boiler
dP
Vent distance
Vent Size
flue
Size from
m2
probe ?
Pa
m2 ceiling
(m)
61
Test
Filename
Comp
Vol m3
test1_2008
0.18
0.027
0.014
test2_2008
0.18
0.027
0.014
test1_100400
6.2
0.014
0.007
0.2
Secondary
6
test1_110400
6.2
0.007
0.003
0.2
Secondary
5
O2 did not deplete by 1.0%; CO2 concentration did not increase to 1.0%.
test2_110400
test3_110400
6.2
6.2
0.003
0
0.002
0
0.2
0.2
Secondary
Secondary
5
5
O2 depleted by 1.0%, CO2 concentration did not reach 1.0%
O2 depleted by 1.0%, CO2 concentration reached 1.0%
test1_120400
6.2
0.027
0
0.2
Secondary
5
O2 did not deplete by 1.0%; CO2 concentration did not increase to 1.0%.
test2_120400
6.2
0
0.014
0.2
Secondary
5
O2 depleted by 1.0%, CO2 concentration reached 1.0%
test3_120400
6.2
0
0.007
0.2
Secondary
5
Similar trend to S/No 144
test1_130400
6.2
0.027
0.014
0.2
Secondary
6
O2 did not deplete by 1.0%; CO2 concentration did not increase to 1.0%.
test2_130400
6.2
0.027
0.014
0.2
Secondary
0
test3_130400
6.2
0.027
0
0.2
Secondary
0
test4_130400
6.2
0
0.014
0.2
Secondary
0
0.2
Secondary
0
0
Comments
Flue blocked using aluminium plate across flue pipe outlet; duct disconnected.
Compartment vents set as BS5440 recommended size.
Flue blocked using aluminium plate across flue pipe outlet; duct disconnected.
Compartment vents set as BS5440 recommended size.
O2 did not deplete by 1.0%; CO2 concentration did not increase to 1.0%.
CO2 (flue) not working
Flue closed / Extract closed. O2 depleted by 1.0%, CO2 concentration reached
1.0%
Flue closed / Extract closed. O2 depleted by 1.0%, CO2 concentration reached
1.0%
Flue closed / Extract closed. O2 depleted by 1.0%, CO2 concentration reached
1.0%
Printed and published by the Health and Safety Executive
C30 1/98
Printed and published by the Health and Safety Executive
C1
12/01
ISBN 0-7176-2120-0
CRR 379
£25.00
9 780717 621200