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Cold water tap firing up boiler?

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RefreshPSC

Mill Hill, London

21-Jan-14 18:55

Writing this post for a friend of mine that has had a long standing dispute with her plumber.

In a nutshell, she commissioned him to replace her entire bathroom and install a new thermostatic shower.

The work was shoddy from the get-go but since the shower was installed, she noticed that turning on any cold tap in the flat, causes her Potterton combi boiler to fire up. The boiler is less than a year old and has never experienced this issue before.

She explained this to the plumber who shrugged it off saying it was nothing to do with him so she got Potterton to inspect. They confirmed that it was nothing wrong with the boiler but said that it looks like it's to do with the new plumbing for the bathroom.

She has also asked a mechanical engineer for his take on it and he has said the same thing.

My question is to qualified and experienced plumbers, what do you think the cause of this could be? We have our own thoughts but want to gather ideas of what to do.

If the cause can be proven to be the plumbers fault, what can she do to get this rectified and what complaints procedure does she need to follow and with who? The plumber is gas safe registered but I'm not sure if her complaint can be put to them if it's not gas related? Or am I wrong?

I'd appreciate your help.

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John Creasey - Boiler Installation & Service, Gas & Heating Maintenance

New Malden, Surrey

22-Jan-14 08:02

Hi - on your last point, 'Gas Safe' sadly will have zero interest unless it is related to a 'gas safety' issue.

Did 'Potterton' not bave any theory on ghe problem having seen it?

John

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Real boiler servicing & maintenance

Enfield, Middlesex

22-Jan-14 09:14

Hi RefreshPSC,

Considering the boilers been checked by the manufacturer and no defects have been found then it sounds like a their may be an issue on the pipe work referred to as a "dead leg" this is were a section on pipe is capped off or does not terminate to an outlet like a tap. In this situation air becomes trapped in the section of pipe and as a result of pressure fluctuations from opening and closing other outlets the water in that section of pipe moves back and forth (think of it like an expansion vessel, same printable) which can cause the boiler to fire up for a short periods.

This is very common specially were systems have been converted from conventional to combi, and the installer has not eliminated redundant pipe work from the system.

The easiest answer and probably the most cost effective is to install a non return valve as close to the boiler as possible on the cold water inlet, but this is just a fix and the non return valve could cause the pressure to drop over time as it clogs up and eventually will fail too, etc.. ideally the dead leg should be traced and eliminated, or terminated in a way that it can be purged.

good luck, hope that helps you out.

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RefreshPSC

Mill Hill, London

22-Jan-14 10:12

Many thanks for the replies. Someone suggested that the hot and cold feeds to the shower may be the wrong way round. Does this sound plausible?

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John Creasey - Boiler Installation & Service, Gas & Heating Maintenance

New Malden, Surrey

22-Jan-14 11:59

Originally posted by: RefreshPSC : View

Many thanks for the replies. Someone suggested that the hot and cold feeds to the shower may be the wrong way round. Does this sound plausible?

Could be on a thermostatic mixer - but suspect somebody would have looked for this already.

I think you said it happens on any cold tap though.

John

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RefreshPSC

Mill Hill, London

22-Jan-14 12:42

Originally posted by: RefreshPSC : View

Many thanks for the replies. Someone suggested that the hot and cold feeds to the shower may be the wrong way round. Does this sound... Read more »

Originally posted by: John Creasey - Boiler Installation & Service, Gas & Heating Maintenance : View

Could be on a thermostatic mixer - but suspect somebody would have looked for this already.

I think you said it happens on any cold tap though.

John

Actually the plumber refused to look at this. Presumably due to the work involved of removing finishes and the mixer to inspect.

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John Creasey - Boiler Installation & Service, Gas & Heating Maintenance

New Malden, Surrey

22-Jan-14 14:44

Have found this before - so not unknown.

Where did you get this 'plumber from'?

J

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RefreshPSC

Mill Hill, London

22-Jan-14 14:48

Originally posted by: John Creasey - Boiler Installation & Service, Gas & Heating Maintenance : View

Have found this before - so not unknown.

Where did you get this 'plumber from'?

J

I found him through one of my plasterers, I'd used him myself on a few small jobs which seemed fine. Passed his details onto my friend and then everything started to go pear shaped.

His website states gas safe.

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Real boiler servicing & maintenance

Enfield, Middlesex

22-Jan-14 19:57

Originally posted by: RefreshPSC : View

Many thanks for the replies. Someone suggested that the hot and cold feeds to the shower may be the wrong way round. Does this sound plausible?

I wouldn't say that having the hot and cold wrong way round would result in the fault you described.

But if you wanted to check the connections to the shower, just set the shower to full cold on the thermostat and run it then repeat this on the hot side, if hot is hot and cold is cold then the connections are fine.

I obviously haven't seen the install but I would still suggest fitting the check valve on the cold inlet, at the least you will confirm if it works, this should narrow things down for you.

all the best.

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John Creasey - Boiler Installation & Service, Gas & Heating Maintenance

New Malden, Surrey

23-Jan-14 06:25

 (Changed by Which? David  why?)

Hi refresh. - you may want to look out for posts by 'Remloc' for help here. Unlike some of us, he generally knows what he is about.

Still unsure why 'any' cold tap is doing this but to be absolutely definite - if the hot and cold have been reversed - absolutely the boiler would fire if the cold side was turned on because its actually the hot.

Good luck

John

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