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.
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.
"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
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 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.
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.
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.
Thank you John for the advice. That is very useful.
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?
ye mum
Another 6 year old post!
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