Boiler using excessive gas after service

ianmcd · 16 Jan 2022

BlueLoo said:
Rightly so.
Why are you against discussion on a discussion board?

Odd.

I have absolutely no problem whatsoever , with anyone offering correct advice, whether Pro or DIY, you however just post absolute crap , and the untrained might believe what you post, which in most cases is completely wrong and sometimes dangerous, if you actually have something constructive to add to a post then please do so, if you havent a clue and are just googling and trying to look smart , it isnt working , we have all seen through you

bernardgreen · 16 Jan 2022

BlueLoo said:
Or ask the mods to only allow proven gas safe engineers to reply to these threads.

There is a vast difference between an engineer who is registered as being safe to work on equipment and an engineer who is competent to diagnose and repair faults on the same equipment.

ianmcd · 16 Jan 2022

BlueLoo said:
There are a few genuine pros on here who clearly know what they are about. You, not so much.

Must admit that made me chuckle, you have absolutely no idea, you are the British kite mark of clowns

ianmcd · 16 Jan 2022

BlueLoo said:
Or ask the mods to only allow proven gas safe engineers to reply to these threads. It seems that's what you want tbh.

Why would I ? there is a section on here called the combustion chamber, where only proven gas engineers may read and comment, so why would I want to re-invent the wheel ? you are quite popular in the closed qualified section and the closed conversations.

ianmcd · 16 Jan 2022

BlueLoo said:
Genuinely,

Please feel free to continue to correct me when i post something wrong or inappropriate.
I'm here to learn like everyone else.

All i ask is you do it politely.
As per the forum rules.

You all take criticism too personally. Use it to make you better engineers, not worse.
Not an easy thing to do, granted.

It has absolutely nothing to do with criticism, so many posters on here think that we have a magic spell, that will contradict what a pro who has visited the system and gave them a diagnosis that they didnt like, many posts we give professional advice, and of course there are many rip off merchants, but as pros on here we give our time and advice totally free, but when someone jumps in and gives completely wrong advice because they are googling and guessing answers, then that is unfair, not only to the OP but to others that think there is a magical solution to their problem, totally agree that the industry is in a bad place, with so called qualified engineers who havent a clue what they are doing, but giving out bad advice on here doesnt help, your neck of the woods suffers more than most, I used to work as a technical advisor to Pheonix gas and have seen first hand the problems over there

CBW · 16 Jan 2022

BlueLoo said:
Why are you against discussion on a discussion board?.

I’m not against discussion, and I would say that’s what the general discussion part of the forum is for, not endless pages of unhelpful, inaccurate and potentially dangerous “advice” on a plumbing and heating section, especially related to gas work.

fixitflav · 16 Jan 2022

bernardgreen said:
It would not prevent the boiler firing up but would allow gas to flow when heating was not requested.

Too many possible faults ( or combination of faults ) to say what may happen in a faulty device.

The point I was making was - unless it's an intermittent fault, the boiler would not fire, no CH. And if it eventually ignites, there could be a bang (depending on the gas/air mixture inside the boiler)

bernardgreen · 16 Jan 2022

fixitflav said:
And if it eventually ignites, there could be a bang (depending on the gas/air mixture inside the boiler)

If I understand it correctly the combustion chamber is purged of any unburnt gas before the ignition sequence is started

fixitflav · 16 Jan 2022

bernardgreen said:
If I understand it correctly the combustion chamber is purged of any unburnt gas before the ignition sequence is started

But can it purge, with the gas valve stuck open? If it were stuck open 24/7, I'd guess the gas consumption would be even higher than reported.

ianmcd · 16 Jan 2022

fixitflav said:
The point I was making was - unless it's an intermittent fault, the boiler would not fire, no CH. And if it eventually ignites, there could be a bang (depending on the gas/air mixture inside the boiler)

bernardgreen said:
If I understand it correctly the combustion chamber is purged of any unburnt gas before the ignition sequence is started

fixitflav said:
But can it purge, with the gas valve stuck open? If it were stuck open 24/7, I'd guess the gas consumption would be even higher than reported.

To clarify, some boilers, not all have a pre ignition attempt purge, not all do, and yes some would give explosive ignition if the gas valve had been letting by, in experience only, any letting by gas valves I have encountered the let by rate has been tiny, I would never argue that it couldnt be higher, just stating what I have found, for a multi function gas valve to let by that volume of gas without a dramatic result I find hard to agree with, but there is a first for everything

fixitflav · 16 Jan 2022

ianmcd said:
To clarify, some boilers, not all have a pre ignition attempt purge, not all do, and yes some would give explosive ignition if the gas valve had been letting by, in experience only, any letting by gas valves I have encountered the let by rate has been tiny, I would never argue that it couldnt be higher, just stating what I have found, for a multi function gas valve to let by that volume of gas without a dramatic result I find hard to agree with, but there is a first for everything

OK, thanks for the clarification

ianmcd · 16 Jan 2022

@fixitflav , gas and air mix have an upper and lower explosive limit, anything outside this ratio will not explode, it is a very small ratio, I have only ever seen one boiler with a fault that resulted in damage, it blew the boiler off the wall, but was actually an installer error and they constantly kept trying to reset the boiler untill it got to explosive level, most modern boilers have so many safety levels that the risk of damage from a letting by gas valve is minimal, not saying impossible but certainly not the norm

DP · 17 Jan 2022

fixitflav said:
But can it purge, with the gas valve stuck open? If it were stuck open 24/7, I'd guess the gas consumption would be even higher than reported.

Yes, but the gas would still be burning from previous ignition phase. Wake up will you

Have seen this in real life

fixitflav · 17 Jan 2022

ianmcd said:
@fixitflav , gas and air mix have an upper and lower explosive limit, anything outside this ratio will not explode, it is a very small ratio, I have only ever seen one boiler with a fault that resulted in damage, it blew the boiler off the wall, but was actually an installer error and they constantly kept trying to reset the boiler untill it got to explosive level, most modern boilers have so many safety levels that the risk of damage from a letting by gas valve is minimal, not saying impossible but certainly not the norm

Thanks, interesting!
I know gas and air mixtures have an upper and lower explosive limit, that's why I said "depending on the gas/air mixture inside the boiler". From memory, I think the flammable range is 3-15% gas/air by volume, though might be for biogas, slightly different for NG.

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Boiler using excessive gas after service

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