Low gas pressure - dangerous?
Mr Benn
engineer said that the gas pressure at the boiler is too low and could be
caused by the pipe from the regulator having too many bends. Despite this,
the boiler has been heating the house effectively.
Is low pressure at the boiler dangerous in any way?
He also said that the boiler was kettling. Is this always a symptom of poor
water circulation and can airlocks cause the poor circulation?
cynic
Without some numbers to consider this is a useless comment from your
gasman. For your peace of mind you should find out what the "working
pressure" at the appliance input is under full load and what the
appliance manufacturers tolerance is. If the thing has been working
for many years without any observable effect it will not suddenly have
suffered a step change in hazard level.
Kettling is most often due to the inside (wet side) of the heat
exchanger being coated with crud and may be cleared with a chemical
clean/flush. Sometimes an injection of "boiler noise silencer" by one
of the popular treatment manufacturers can be wonderfully effective.
The kettling stops as if by magic.
TheScullster
"Mr Benn" wrote
Is it possible to test the supply close to the meter?
Can't remember what we were having done, but when our gas pressure was found
to be low, our gas supplier came out very promptly and fitted a new
regulator to cure the problem - free of charge :).
Did the guy passing comment on boiler noise add/check for inhibitor in the
heating system?
Although there are products specifically to quieten boiler noise, I found
that running without inhibitor was noisier and also that Fernox was the best
at silencing the system noise generally.
Phil
Andrew Gabriel
cynic <icel...@talktalk.net> writes:
> On 11 Sep, 11:44, "Mr Benn" <nos...@invalid.invalid> wrote:
>> My sister has just had her central heating boiler serviced and the gas
>> engineer said that the gas pressure at the boiler is too low and could be
>> caused by the pipe from the regulator having too many bends. �Despite this,
>> the boiler has been heating the house effectively.
>>
>> Is low pressure at the boiler dangerous in any way?
>>
>> He also said that the boiler was kettling. �Is this always a symptom of poor
>> water circulation and can airlocks cause the poor circulation?
> Without some numbers to consider this is a useless comment from your
> gasman. For your peace of mind you should find out what the "working
> pressure" at the appliance input is under full load and what the
> appliance manufacturers tolerance is. If the thing has been working
> for many years without any observable effect it will not suddenly have
> suffered a step change in hazard level.
Although you may not have realised the potential hazards, such
as a gas hob burner set low might go out if the gas pressure to
it drops when the boiler fires up.
> Kettling is most often due to the inside (wet side) of the heat
> exchanger being coated with crud and may be cleared with a chemical
> clean/flush. Sometimes an injection of "boiler noise silencer" by one
> of the popular treatment manufacturers can be wonderfully effective.
> The kettling stops as if by magic.
Kettling isn't normally dangerous, but is probably indicative of
less efficient operation and may shorten the life of the heat
exchanger if it's bad enough to cause it to run significantly
hotter than designed, due to poor conduction through to the water.
--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]
YAPH
From the kettling comment I'd guess that the boiler is fairly ancient, in
which case its burner probably runs at a much lower pressure than the gas
at the inlet to the boiler. *IF* this is so then the below-standard gas
pressure is probably not an actual safety issue. (In any case if it were a
significant safety issue the engineer who serviced it should have issued
an "At Risk" warning notice and - with the user's permission - left the
boiler switched off. Though they should have issued a "Not to Current
Standards" notice regarding the low pressure.) On a (probably more modern)
boiler requiring a burner pressure closer to the inlet pressure then low
inlet pressure could cause an incorrect gas mixture and incorrect
combustion which would be a safety issue.
The pressure drop in the pipework is a function of the length of pipework,
number of bends (each sharp 90 degree bend counts as half a metre of
straight pipe) and pipe diameter (for a typical combi boiler, for example,
1 metre of 15mm pipe causes the same pressure drop as about 20 metres of
22mm). If the regulator at the meter is providing lower pressure than it
ought, it should be adjusted or replaced (by the gas emergency service
provider - formerly Transco - who you get by calling 0800 111 999) but if
the regulator is set correctly then it's not permissible (though not
unknown) to tweak it up.
--
John Stumbles -- http://yaph.co.uk
I used to think the brain was the most interesting part of the body
- until I realised what was telling me that
Mike Barnes
Similar situation here: the service engineer said that the pressure at
the meter was fine but at the boiler it was borderline. It's a ten-year-
old boiler, its first service, and he said that it was remarkably clean.
So I think the combustion must be OK.
There is a long tortuous path from the meter to the boiler. He proposed
replacing the relatively accessible part of the pipe with a larger
diameter, but I didn't consider it worth doing. He didn't say anything
about the low pressure possibly being dangerous, or seem at all
surprised that I was happy to leave things as they are.
I also mentioned the kettling (which is very noisy, and possibly always
has been) and he basically just shrugged. I'm interested to hear from
this thread that you get some additive to address that problem, and I'll
give that a go.
--
Mike Barnes
Mr Benn
news:7h02teF...@mid.individual.net...
<useful information snipped>
> John Stumbles -- http://yaph.co.uk
Thank you John for the advice. That is very useful.
Mr Benn
"Mike Barnes" <mikeb...@bluebottle.com> wrote in message
news:oJHsgMPW...@g52lk5g23lkgk3lk345g.invalid...
Someone else suggested using Fernox in the system to clean it out. I am
wondering if it is scale in the boiler which is causing the kettling. Will
Fernox remove scale?
kai...@gmail.com
alan_m
Another 6 year old post!
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Brian-Gaff
Well maybe they have blown up by now.
Low pressure can be dangerous if there is an explosive mix with air
present in the pipe for some reason.
Brian
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