The fan on my ~20-year-old Baxi Solo WM70/4PF seems to be getting a bit hot!

We noticed a smell like food burnt onto a hotplate (the boiler's in the
kitchen) and eventually tracked it down to the boiler. The fan in
question was reconditioned by Geoff a couple (maybe 3 ) years ago. The
fan spins freely, and works ok - and the boiler seems to work ok. The
smell seems to be coming from the fan windings.

Also, the fan casing seems a bit discoloured (a darkish bluey green
colour instead of bright galvanised) as though *that* has got hotter
than usual.

I've got a spare fan (used, but in working order) which I could fit -
but if the root of the problem is elsewhere, that could suffer the same
fate.

Anyone got any ideas as to what may make the fan body overheat? Am I
right in thinking that it's designed to blow hot (combustion) air *out*
rather than cold air *in*?
--
Cheers,
Roger
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On 24/06/2012 18:12, Roger Mills wrote:
Am I right in thinking that it's designed to blow hot (combustion) air
*out* rather than cold air *in*?


While we wait for Geoff - my glow-worm sucks cold in, and pressurises
the casing. The only significant outlet from the casing is through the
burners, then the heat exchange, then the exhaust. This design has the
sensible benefit that any casing leak lets cold fresh air into the room,
and that the burners won't run unless the casing is on and it is up to
pressure.

It's not much pressure BTW.

Andy

my glow-worm sucks cold in, and pressurises
the casing. The only significant outlet from the casing is through the
burners, then the heat exchange, then the exhaust. This design has the
sensible benefit that any casing leak lets cold fresh air into the room,


SENSIBLE BENEFIT??

Positive case pressure boilers are the most potentionly dangerous fan flue
boilers there are.

The slightest leak in the casing or the casing seals will allow the
products of combustion into room and and due to the poor combustion that
is likely to occur, high levels of carbon monoxide (CO) could be produced

Fresh cold air will NOT be blown into the room.

These types of boiler can be death traps if not properly maintained.

--- Posted via news://freenews.netfront.net/ - Complaints to ---

In message , Roger Mills
writes
The fan on my ~20-year-old Baxi Solo WM70/4PF seems to be getting a bit hot!

We noticed a smell like food burnt onto a hotplate (the boiler's in the
kitchen) and eventually tracked it down to the boiler. The fan in
question was reconditioned by Geoff a couple (maybe 3 ) years ago. The
fan spins freely, and works ok - and the boiler seems to work ok. The
smell seems to be coming from the fan windings.

Is the plastic cooling rotor on the end of the shaft still intact?



Also, the fan casing seems a bit discoloured (a darkish bluey green
colour instead of bright galvanised) as though *that* has got hotter
than usual.

I presume it's plated, not painted and the bluish hue has appeared since
it was installed - the boiler is running too hot


I've got a spare fan (used, but in working order) which I could fit -
but if the root of the problem is elsewhere, that could suffer the same
fate.

Yes - get someone in to sort it out, the boiler is overheating

or ring us tomorrow 01923 229224


Anyone got any ideas as to what may make the fan body overheat? Am I
right in thinking that it's designed to blow hot (combustion) air *out*
rather than cold air *in*?

--
geoff

geoff wrote:

Yes - get someone in to sort it out, the boiler is overheating

or ring us tomorrow 01923 229224

While you are around.
My mate ruined a PCB on a new boiler on Thursday - Potterton Gold H,
found a leak on the pipes, had to drain down, found the drain point is
above the PCB, then the hosepipe came off, and went over the PCB, only a
small bit, but enough to fry it when turned on (he didnt think any water
had gone on it). There were balck tracking marks on the back of the PCB.

Anyway, if such a thing happened in the future, could you repair it? And
how fast?

Thanks
Alan.


--
To reply by e-mail, change the ' + ' to 'plus'.

On 25/06/2012 00:29, geoff wrote:
In message , Roger Mills
writes
The fan on my ~20-year-old Baxi Solo WM70/4PF seems to be getting a
bit hot!

We noticed a smell like food burnt onto a hotplate (the boiler's in
the kitchen) and eventually tracked it down to the boiler. The fan in
question was reconditioned by Geoff a couple (maybe 3 ) years ago. The
fan spins freely, and works ok - and the boiler seems to work ok. The
smell seems to be coming from the fan windings.

Is the plastic cooling rotor on the end of the shaft still intact?


Yes



Also, the fan casing seems a bit discoloured (a darkish bluey green
colour instead of bright galvanised) as though *that* has got hotter
than usual.

I presume it's plated, not painted and the bluish hue has appeared since
it was installed - the boiler is running too hot


Yes, it's either zinc plated or galvanised - somesuch. Yes, the hue has
appeared fairly recently.


I've got a spare fan (used, but in working order) which I could fit -
but if the root of the problem is elsewhere, that could suffer the
same fate.

Yes - get someone in to sort it out, the boiler is overheating

or ring us tomorrow 01923 229224


Yes, I guess it's overheating in one sense or another. How many modes of
overheating are there? I checked the gas consumption rate in case
something had happened to the pressure setting on the gas valve, but
that's about right - so the heat input isn't excessive unless the
calorific value has dramatically increased, which is pretty unlikely.

The boiler stat is cutting in and out ok to regulate the water output
temperature correctly.

BUT, the exhaust coming out of the flue seems much hotter than usual.
From memory, it has always been 'warm' but now, I can't hold my hand
any closer than 500mm from the outlet.

From the installation manual, it is apparent that there are various
baffles inside - presumably to direct the flame to the right places. If
one of those had an unscheduled hole in it, could that explain the symptoms?
--
Cheers,
Roger
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On Jun 25, 8:47*am, Roger Mills wrote:
On 25/06/2012 00:29, geoff wrote:

In message , Roger Mills
writes
The fan on my ~20-year-old Baxi Solo WM70/4PF seems to be getting a
bit hot!

We noticed a smell like food burnt onto a hotplate (the boiler's in
the kitchen) and eventually tracked it down to the boiler. The fan in
question was reconditioned by Geoff a couple (maybe 3 ) years ago. The
fan spins freely, and works ok - and the boiler seems to work ok. The
smell seems to be coming from the fan windings.

Is the plastic cooling rotor on the end of the shaft still intact?

Yes



Also, the fan casing seems a bit discoloured (a darkish bluey green
colour instead of bright galvanised) as though *that* has got hotter
than usual.

I presume it's plated, not painted and the bluish hue has appeared since
it was installed - the boiler is running too hot

Yes, it's either zinc plated or galvanised - somesuch. Yes, the hue has
appeared fairly recently.



I've got a spare fan (used, but in working order) which I could fit -
but if the root of the problem is elsewhere, that could suffer the
same fate.

Yes - get someone in to sort it out, the boiler is overheating

or ring us tomorrow 01923 229224

Yes, I guess it's overheating in one sense or another. How many modes of
overheating are there? I checked the gas consumption rate in case
something had happened to the pressure setting on the gas valve, but
that's about right - so the heat input isn't excessive unless the
calorific value has dramatically increased, which is pretty unlikely.

The boiler stat is cutting in and out ok to regulate the water output
temperature correctly.

BUT, the exhaust coming out of the flue seems much hotter than usual.
*From memory, it has always been 'warm' but now, I can't hold my hand
any closer than 500mm from the outlet.

*From the installation manual, it is apparent that there are various
baffles inside - presumably to direct the flame to the right places. If
one of those had an unscheduled hole in it, could that explain the symptoms?
--
Cheers,
Roger
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checked.

Have you checked the heat exchanger is clear and the spread of hot gas
flow is distributed over the whole area? I havent picked up tools for
some time now but it woulkd be a good start to ensure the airways/
burner/heat exchanger/flue exit is clear then if so check the gas rate.

On 25/06/2012 08:47, Roger Mills wrote:



Yes, I guess it's overheating in one sense or another. How many modes of
overheating are there? I checked the gas consumption rate in case
something had happened to the pressure setting on the gas valve, but
that's about right - so the heat input isn't excessive unless the
calorific value has dramatically increased, which is pretty unlikely.

The boiler stat is cutting in and out ok to regulate the water output
temperature correctly.

BUT, the exhaust coming out of the flue seems much hotter than usual.
From memory, it has always been 'warm' but now, I can't hold my hand
any closer than 500mm from the outlet.

From the installation manual, it is apparent that there are various
baffles inside - presumably to direct the flame to the right places. If
one of those had an unscheduled hole in it, could that explain the
symptoms?

To add a bit more to my previous post . . .

Here's a picture of the discoloured fan and the spare one side by side.
No guesses as to which is which!

http://www.mills37.plus.com/Fans.jpg

And here's a picture looking down through the hole with the fan removed.

http://www.mills37.plus.com/Fan_hole.jpg

There's nothing untoward when looking down through the fan inlet hole,
but maybe I'd need to dismantle a lot more to see any problems with the
baffles?
--
Cheers,
Roger
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On 25/06/2012 11:43, cynic wrote:


Have you checked the heat exchanger is clear and the spread of hot gas
flow is distributed over the whole area? I havent picked up tools for
some time now but it woulkd be a good start to ensure the airways/
burner/heat exchanger/flue exit is clear then if so check the gas rate.

No, that's probably the next thing to check - I shall have to bite the
bullet and take the front off the combustion chamber. If I do that, I
can remove any obvious crud, but how can I check that the flame is
evenly distributed? [I obviously can't fire it up when it's in bits!]

As mentioned earlier, I've already checked the gas consumption rate, and
it's in the right ballpark - about midway between the max and min
settings for the boiler.
--
Cheers,
Roger
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In article ,
Roger Mills writes:
On 25/06/2012 11:43, cynic wrote:


Have you checked the heat exchanger is clear and the spread of hot gas
flow is distributed over the whole area? I havent picked up tools for
some time now but it woulkd be a good start to ensure the airways/
burner/heat exchanger/flue exit is clear then if so check the gas rate.

No, that's probably the next thing to check - I shall have to bite the
bullet and take the front off the combustion chamber. If I do that, I
can remove any obvious crud, but how can I check that the flame is
evenly distributed? [I obviously can't fire it up when it's in bits!]

As mentioned earlier, I've already checked the gas consumption rate, and
it's in the right ballpark - about midway between the max and min
settings for the boiler.

Have you measured the flue gas temperature?
Checking back over my service readings for Potterton Suprima and Profile
conventional boilers, flue gas temperature readings are 145-160C,
although probably neither were on their highest setting, but that's
only going to add at most another 20C. The highest for anything I've
measured is a multipoint water heater at 208C.

(Obviously, condensing boilers are very much lower.)

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On 25/06/2012 13:45, Andrew Gabriel wrote:
In ,
Roger writes:
On 25/06/2012 11:43, cynic wrote:


Have you checked the heat exchanger is clear and the spread of hot gas
flow is distributed over the whole area? I havent picked up tools for
some time now but it woulkd be a good start to ensure the airways/
burner/heat exchanger/flue exit is clear then if so check the gas rate.

No, that's probably the next thing to check - I shall have to bite the
bullet and take the front off the combustion chamber. If I do that, I
can remove any obvious crud, but how can I check that the flame is
evenly distributed? [I obviously can't fire it up when it's in bits!]

As mentioned earlier, I've already checked the gas consumption rate, and
it's in the right ballpark - about midway between the max and min
settings for the boiler.

Have you measured the flue gas temperature?

No. I don't have any suitable measuring equipment, and I don't know what
it *should* be.

As noted earlier, it *seems*[1] to be a lot hotter than I previously
remember it being - and the fan body, through which the exhaust gases
pass, has recently become discoloured, and there's a hot 'smell' when
it's running.

What could cause the flue gas temperature to rise? [There's quite a
powerful flow]

[1] Calibrated hand held in exhaust flow!
--
Cheers,
Roger
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checked.

In article ,
Roger Mills writes:

What could cause the flue gas temperature to rise? [There's quite a
powerful flow]

Off the top of my head...

Burner pressure too high, so flame (combustion) happening further
through (or even past) the heat exchanger. However, that would also
give a high gas rate, which you already checked. Heat exchanger
partially blocked to flue gasses might also have the same effect of
delaying full combustion, without using a higher gas rate. *

Heat exchanger has become thermally insulating, either on the inside
or outside, e.g. a layer of soot (or other debris), or a layer of
hard water scale (usually makes it noisy, like a powerful kettle).

Heat exchanger isn't full of water, e.g. an air pocket. (Don't know
if that's possible with your boiler model).


*Is there a sight glass so you can see the flame colour?
Even if there is, it usually only gives direct sight of the bottoms
of the flames, but they get yellow/sooty at the tops first. However,
you can sometimes tell that light is being generated further up
the heat exchanger by seeing it reflected off the burners or
something else visible at the bottom which has line-of-sight up the
heat exchanger.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On 25/06/2012 16:01, Andrew Gabriel wrote:
In ,
Roger writes:

What could cause the flue gas temperature to rise? [There's quite a
powerful flow]

Off the top of my head...

Burner pressure too high, so flame (combustion) happening further
through (or even past) the heat exchanger. However, that would also
give a high gas rate, which you already checked.

Indeed.

Heat exchanger
partially blocked to flue gasses might also have the same effect of
delaying full combustion, without using a higher gas rate. *

That's a possibility. I shall have to dismantle it to check that.

Heat exchanger has become thermally insulating, either on the inside
or outside, e.g. a layer of soot (or other debris), or a layer of
hard water scale (usually makes it noisy, like a powerful kettle).


Well, there *could* be soot on it. However, it's only a couple of years
since it was serviced - having been previously untouched for at least 10
years - and the bloke who did it then said that it was as clean as a
whistle.

It's a vented system, but it's had very few water changes during the
boiler's 22 year life, and it was all washed out and re-inhibited a
couple of years ago, so there *shouldn't* be too much scale.

Heat exchanger isn't full of water, e.g. an air pocket. (Don't know
if that's possible with your boiler model).

Unlikely, I would have thought. The boiler is on the ground floor, with
pumped circulation up to the airing cupboard - and beyond. There's
plenty of water in the F&E tank.


*Is there a sight glass so you can see the flame colour?
Even if there is, it usually only gives direct sight of the bottoms
of the flames, but they get yellow/sooty at the tops first. However,
you can sometimes tell that light is being generated further up
the heat exchanger by seeing it reflected off the burners or
something else visible at the bottom which has line-of-sight up the
heat exchanger.


Yes, there is a sight glass, and the part of the flame which I can see
looks blue.
--
Cheers,
Roger
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In message , A.Lee
writes
geoff wrote:

Yes - get someone in to sort it out, the boiler is overheating

or ring us tomorrow 01923 229224

While you are around.

I'm always around

My mate ruined a PCB on a new boiler on Thursday - Potterton Gold H,
found a leak on the pipes, had to drain down, found the drain point is
above the PCB, then the hosepipe came off, and went over the PCB, only a
small bit, but enough to fry it when turned on (he didnt think any water
had gone on it). There were balck tracking marks on the back of the PCB.

Anyway, if such a thing happened in the future, could you repair it? And
how fast?


With a few exceptions, we only repair pcbs that we have a test rig for

Do you mean the Potterton Gold Promax 28HE ? Yes, we have a test set for
that, but the problem with "water" damage is that the water is a highly
corrosive ionic liquid which eats away at any component it comes in
contact with. Sometimes these are not economically repairable

If its a board we can do, then we aim at a same day / in one day, out
the next turnaround


--
geoff

On 24/06/2012 22:48, Heliotrope Smith wrote:


my glow-worm sucks cold in, and pressurises
the casing. The only significant outlet from the casing is through the
burners, then the heat exchange, then the exhaust. This design has the
sensible benefit that any casing leak lets cold fresh air into the room,


SENSIBLE BENEFIT??

Positive case pressure boilers are the most potentionly dangerous fan flue
boilers there are.

The slightest leak in the casing or the casing seals will allow the
products of combustion into room and and due to the poor combustion that
is likely to occur, high levels of carbon monoxide (CO) could be produced

Fresh cold air will NOT be blown into the room.

These types of boiler can be death traps if not properly maintained.


Hmm I'm trying to work out how this could be. And failing.

The air next to the case is fresh air. It entirely surrounds the
burner, except for the flue. Any leak would allow that fresh air into
the room.

How could that let combustion products into the room?

Andy

On 25/06/2012 21:57, Andy Champ wrote:
On 24/06/2012 22:48, Heliotrope Smith wrote:


my glow-worm sucks cold in, and pressurises
the casing. The only significant outlet from the casing is through the
burners, then the heat exchange, then the exhaust. This design has the
sensible benefit that any casing leak lets cold fresh air into the room,


SENSIBLE BENEFIT??

Positive case pressure boilers are the most potentionly dangerous fan
flue
boilers there are.

The slightest leak in the casing or the casing seals will allow the
products of combustion into room and and due to the poor combustion that
is likely to occur, high levels of carbon monoxide (CO) could be produced

Fresh cold air will NOT be blown into the room.

These types of boiler can be death traps if not properly maintained.


Hmm I'm trying to work out how this could be. And failing.

The air next to the case is fresh air. It entirely surrounds the burner,
except for the flue. Any leak would allow that fresh air into the room.

How could that let combustion products into the room?

Andy

I think he's saying that if you pump fresh air into the boiler, the
combustion chamber will be at above room pressure. If there is a leak,
the products of combustion could leak into the room.

Whereas, if the fan is pumping the exhaust *out*, the combustion chamber
is *below* room pressure . . .
--
Cheers,
Roger
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checked.

I think he's saying that if you pump fresh air into the boiler, the
combustion chamber will be at above room pressure. If there is a leak,
the products of combustion could leak into the room.

Whereas, if the fan is pumping the exhaust *out*, the combustion
chamber is *below* room pressure . . .

Thanks. Yes in a nut shell that's about it.

Do a Google on positive pressure boilers.
Plenty of information on how dangerousthese can
be.

--- Posted via news://freenews.netfront.net/ - Complaints to ---

On 26/06/2012 20:40, Heliotrope Smith wrote:
I think he's saying that if you pump fresh air into the boiler, the
combustion chamber will be at above room pressure. If there is a leak,
the products of combustion could leak into the room.

Whereas, if the fan is pumping the exhaust *out*, the combustion
chamber is *below* room pressure . . .
Thanks. Yes in a nut shell that's about it.

Do a Google on positive pressure boilers.
Plenty of information on how dangerousthese can
be.

--- Posted via news://freenews.netfront.net/ - Complaints to ---

Yep, when a positive pressure boiler is serviced, they usually test the
casing seals with a smoke match or similar.

--
David

On 26/06/2012 21:40, gremlin_95 wrote:
On 26/06/2012 20:40, Heliotrope Smith wrote:
I think he's saying that if you pump fresh air into the boiler, the
combustion chamber will be at above room pressure. If there is a leak,
the products of combustion could leak into the room.

Whereas, if the fan is pumping the exhaust *out*, the combustion
chamber is *below* room pressure . . .
Thanks. Yes in a nut shell that's about it.

Do a Google on positive pressure boilers.
Plenty of information on how dangerousthese can
be.

--- Posted via news://freenews.netfront.net/ - Complaints to
---

Yep, when a positive pressure boiler is serviced, they usually test the
casing seals with a smoke match or similar.



OK, I'm completely confused by this. There's widespread industry concern
over the safety of these things - and yet I can't see how they (or mine
at least) is a problem.

There is a large case which contains air pressurised by a fan (you know
whose!) the fan sucking air on from outside through the balanced flue.

Entirely enclosed within this case, and touching the case nowhere except
where the flue goes through, is a burner and heat exchanger.

The exhaust side of the flue is open to the outside.

Normal airflow is in, through the fan, into the case, up past the
burner, through the heat exchanger, and out of the flue.

A leak in the case would result in fresh air from the main body of the
casing going into the room.

A hole in the heat exchanger would allow air from the case to bypass the
burner. Not good for efficiency, but it would have to be a damn big hole
to make much difference.

The exhaust part of the flu is in the middle of the inlet part until
it's outside the house. Any leak here would result in exhaust gasses
mixing into the inlet air. That would undoubtedly be a Bad Thing, as
the boiler would probably generate CO and blow it all over next door's
garden. But there we have the only way I see a risk - case leaks AND
flue leaks, flue leak to the extent that the boiler is starved of oxygen
and generating CO. So TWO faults.

What am I missing?

Andy

On 27/06/2012 20:41, Andy Champ wrote:


A leak in the case would result in fresh air from the main body of the
casing going into the room.


If the leak is above burner level, it won't be fresh air that comes out
- but the products of combustion.

What am I missing?


The obvious!
--
Cheers,
Roger
____________
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checked.

In article ,
Roger Mills writes:
On 27/06/2012 20:41, Andy Champ wrote:


A leak in the case would result in fresh air from the main body of the
casing going into the room.
If the leak is above burner level, it won't be fresh air that comes out
- but the products of combustion.

If there's a leak between burner and flue, it will just blow the higher
pressure case air into the flue, bypassing the burner. If it's so
bad as to cause the burner to produce CO, it will be ejected out
of the flue, but couldn't even get back into the boiler casing,
never mind the room. If the boiler has a pressure test as part
of the ignition sequence, a leak that bad would cause the pressure
test to fail and abort the ignition sequence.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On 27/06/2012 23:06, Andrew Gabriel wrote:
In ,
Roger writes:
On 27/06/2012 20:41, Andy Champ wrote:


A leak in the case would result in fresh air from the main body of the
casing going into the room.
If the leak is above burner level, it won't be fresh air that comes out
- but the products of combustion.

If there's a leak between burner and flue, it will just blow the higher
pressure case air into the flue, bypassing the burner. If it's so
bad as to cause the burner to produce CO, it will be ejected out
of the flue, but couldn't even get back into the boiler casing,
never mind the room. If the boiler has a pressure test as part
of the ignition sequence, a leak that bad would cause the pressure
test to fail and abort the ignition sequence.

I'm not sure which particular boiler you have in mind but if the fan in
my Baxi Solo were in the inlet rather than the outlet - so that the
combustion chamber was at a positive pressure relative to the room - and
if there were a leak in the rope seal at the front of the chamber, some
of the products of combustion would get into the room rather than going
through the heat exchanger and out of the flue.
--
Cheers,
Roger
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On 25/06/2012 00:29, geoff wrote:


Yes - get someone in to sort it out, the boiler is overheating

or ring us tomorrow 01923 229224


Yes, I did both!

I got the bloke who originally installed it to have a look at it. He
took the combustion chamber to bits and cleaned it out. There was a bit
of rusty crud in there, but nothing untoward - and no soot build-up or
anything. The only obvious problem was that some of the lower 'fingers'
on the centre sections of the two baffles which fit between the three
sections of the heat exchanger (No. 39 on the picture at
http://www.mills37.plus.com/Baffles.png) were burnt to about half of
their original length. He put the baffles back in the other way up -
with the good bits nearest the flames - and the problem seems to have
gone away - for the time being, at any rate.

Clearly, it would be desirable to fit new baffles but, according the
Baxi site, they're no longer available. I can't help feeling that there
will be some lurking on somebody's shelf somewhere or other - if only I
knew where to find them. Do any of you have any contacts who stockpile
obsolete boiler parts? FWIW, the Baxi Part Number is 226421, and the Gas
Council Number is 364 794.
--
Cheers,
Roger
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In message , Roger Mills
writes
On 25/06/2012 00:29, geoff wrote:


Yes - get someone in to sort it out, the boiler is overheating

or ring us tomorrow 01923 229224


Yes, I did both!


Having passed you on to Max, were you happy with the answer he gave you?


--
geoff

On 28/06/2012 19:08, geoff wrote:
In message , Roger Mills
writes
On 25/06/2012 00:29, geoff wrote:


Yes - get someone in to sort it out, the boiler is overheating

or ring us tomorrow 01923 229224


Yes, I did both!


Having passed you on to Max, were you happy with the answer he gave you?


Yes, thanks - once I'd steered him away from saying that, because it was
'over-heating', there must be a problem with the boiler stat. In the
end, he confirmed what I already suspected - that we needed to dismantle
the combustion chamber to see what was going on inside.
--
Cheers,
Roger
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checked.

On 27/06/2012 23:06, Andrew Gabriel wrote:
In article ,
Roger Mills writes:
On 27/06/2012 20:41, Andy Champ wrote:


A leak in the case would result in fresh air from the main body of the
casing going into the room.
If the leak is above burner level, it won't be fresh air that comes out
- but the products of combustion.


Even _above_ burner level it's only pressurised fresh air next to the
case. I meant it about the combustion chamber and heat exchanger being
_entirely_ surrounded. The fact that the casing runs cold is a dead
giveaway!

If there's a leak between burner and flue, it will just blow the higher
pressure case air into the flue, bypassing the burner. If it's so
bad as to cause the burner to produce CO, it will be ejected out
of the flue, but couldn't even get back into the boiler casing,
never mind the room. If the boiler has a pressure test as part
of the ignition sequence, a leak that bad would cause the pressure
test to fail and abort the ignition sequence.


It could choke itself with a leak on the suction side of the fan into
the exhaust - it would suck exhaust into the intake.

But it does have a pressure switch.

Andy