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I was hoping someone could give some advice about our problem.

 

2 weeks ago, our Valiant boiler started losing pressure, approximately 1 bar every day. I switched it off and isolated the return and flow using the valves underneath the boiler, but the pressure kept dropping at the same rate. Hence the assumption was boiler problem, not system leak.

 

We've got BG boiler cover, so gave them a call. They isolated the boiler the same way to double check - boiler still losing pressure. So they investigated further - bags placed over condensate and pressure relief pipe to catch water (nothing there). They found water inside a container in the boiler - this led to them replacing the heat exchanger. But pressure still dropping (same rate).

 

So, boiler completely disconnected and capped off (return and flow, mains supply and hot and cold feeds, but not gas supply). Pressure held perfectly.

 

Before reconnecting, the expansion vessel was noted to be quite flat, so this was pumped (but they stated this was unrelated as pressure was not rising with heating on).

 

Boiler now reconnected, but is still losing pressure.

 

So, BG say it's a system leak. Okay, but why is there pressure loss in the boiler when we use the isolation valves under the boiler? BG say those valves definitely hold water as they were used when disconnecting the boiler - however BG suggest that they 'can hold water, but perhaps not pressure'. That doesn't makes sense to me :)

 

Before we start ripping up flooring looking for a leak, can anything think of a reason that may have been overlooked? Is it possible for the isolation valves to 'not hold pressure' but happily 'hold water'? Is there 'something' different when using isolation valves compared to completely disconnecting and capping off return and flow pipes?

 

Any thoughts, however obscure, would be much appreciated![/

 

why o why have BG not sorted this. Vaillant boiler iso valves are pretty damm good. First off find out if leak is within boiler. So increase pressure up to 2 bar and turn off all iso valves apart from gas. Bag the prv and condensate and leave for min 12 hours (24 is better). Then has boiler lost pressure. If yes then leak in boiler, if no then elsewhere in pipes. Check for water in prv bag and condensate bag. Sometimes a condensate bag can be dry but you will find a little spillage in the boiler itself from dripping out the syphon trap. I think BG went the easy route of replacing your hot water heat exchanger. My feeling is that the leak is in main heat exchanger. Pretty rare for a stainless vaillant heat ex but can happen.

 

when you last had boiler isolated, you said it dropped pressure. are u sure boiler was dry inside

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Agree with Andy, Vaillant isolations on CH have never passed water (or pressure) in my experience. Should be a simple problem to diagnose so again, agree with the above, pretty poor for BG not to find problem and simply resort to 'throwing' new parts at a boiler

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In fact, can anyone recommend a good, reliable economic boiler?

I've had vaillant in the past and they have been good.

 

Vaillant are excellent boilers though the control panel on the new version is not as customer friendly. For much less you could have an Ideal Logic+ with 7yr warranty. Economy wise they are all very similar as all boilers are 'A' rated, around 90% efficiency. Happy to view your property, offer advice/discuss your options and provide a free written quote, cheers, Steve

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why o why have BG not sorted this. Vaillant boiler iso valves are pretty damm good. First off find out if leak is within boiler. So increase pressure up to 2 bar and turn off all iso valves apart from gas. Bag the prv and condensate and leave for min 12 hours (24 is better). Then has boiler lost pressure. If yes then leak in boiler, if no then elsewhere in pipes. Check for water in prv bag and condensate bag. Sometimes a condensate bag can be dry but you will find a little spillage in the boiler itself from dripping out the syphon trap. I think BG went the easy route of replacing your hot water heat exchanger. My feeling is that the leak is in main heat exchanger. Pretty rare for a stainless vaillant heat ex but can happen.

 

when you last had boiler isolated, you said it dropped pressure. are u sure boiler was dry inside

 

They have completely disconnected the boiler and capped off the pipes, and it kept pressure perfectly, so they are saying the iso valves must be faulty - however the iso valves were holding water fine (according to the engineer - as they were used to isolate while the boiler was disconnected and pipes capped).

 

So my concern is, assuming the iso valves are fine, why is the boiler losing pressure when these is volves are closed, but not losing pressure when its been physically disconnected and capped off?

 

Could it be that one of the pipes that was actually disconnected could be the problem - i.e. while connected, it's doing something that affects system pressure? The following was capped off:

 

- return and flow

- the hot and cold water pipes for the water system

- the incoming mains feed (this has a bendy pipe that had been physically taken off at both ends - I assume there was some kind of isolation valve involved)

 

From memory, I believe the hot/cold and mains feed were reconnected first, then after 24 hours the return and flow were reconnected (back to 1 bar per day pressure drop)

 

BTW, further info:

 

I believe it was the primary heat exchanger that was originally replaced. They did find water inside - they said it was the most expensive part you can replace (£350). They also said the the 'secondary' exchanger was a really obscure possibility, which is apparently why they also capped off the hot/cold pipes, just to make sure.

 

We've checked the boiler for water leaks inside and out, nothing as far as we can see - bone dry. Condensate and pressure release pipe bagged overnight with boiler off and nothing inside in the morning (apressure drop of around 0.4 bar had occurred).

 

If the iso valves weren't happily holding water, I'd be happy to accept they were faulty and that it's a system issue, but it doesn't seem possible that those valves can hold water but not pressure.

 

Is there any way, no matter how obscure, that it can still be a boiler issue if every single pipe going into the boiler is physically capped off (except for the incoming gas supply pipe)?

Edited by shadow

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I have an old Ideal Wlx boiler regular boiler that is over twenty years old. I am looking to replace it with either a combi or system boiler which are both pressurised.

 

I have had a number of quotes but could do with advice on whether my existing radiators mostly 30+ years old will cope with a pressurised system.

 

I have been advised to have a powerflush as the radiators have had minimal maintenance over the years but have been told both that there is little likelihood of the radiators failing or a very strong possibility. What do people think?

 

Secondly, I wonder what boiler to get. There are usually two of us here - sometimes four. The house is small- medium 3 bed dormer semi built in 1971. I have beent told that the WB 27CDi is very good combi, better than the WB 24si or the Ideal Logic+ but that they are all good boilers.

 

If I go for a system or regular boiler - both the WB and Logic 18kw have been recommended.

 

I would appreciate any advice.

 

Hi sometimes people tend to worry about the pressure from a combi when you have old radiators, its just a matter of luck really if your radiators are in good condition on the inside there should be no issue.

We fitted a new boiler this year on a system where the radiators were upto 30 years old and had no problems at all.

If your looking at new boilers i have to say Ideal logic plus all day long over any other make, we have been fitting these since they hit the market and never had a fault yet.

If you require any advice feel free to ask or call anytime cheers jon.

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In fact, can anyone recommend a good, reliable economic boiler?

I've had vaillant in the past and they have been good.

 

Hi if you go for a new boiler the only one i would have is the Ideal logic plus, the best around and great price call if you require any info or a free quote cheers jon.

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Thanks for the quick reply. I might get a new boiler anyway as this one is getting on a bit. That should, presumably, make things a little more simple?

 

Hi sheff_surf,

 

We can install a brand new vaillant with 5 years warranty. Check out our fixed price deals at http://www.oneheating.co.uk, or http://www.greenbuyenergy.co.uk

 

We can now offer flexible payments from £17/month or buy now pay later.

 

Regards

 

Steven Peacock

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Hi, we are doing some work in our house and want to move the combi boiler from the kitchen to the garage. Firstly, would there be a problem having it in the garage as it does get cold in winter (would this affect the boiler) and is it a big job? As far as I can tell, it's the gas supply and water supply that would need moving? The gas metre is in the garage anyway so seems quite do-able!

 

Besides insulating the pipework, it is advisable to have a frost and pipe stat fitted when siting a boiler in an unheated space.

 

Steve Peacock

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In fact, can anyone recommend a good, reliable economic boiler?

I've had vaillant in the past and they have been good.

 

Ideal logic + with a 7 year warranty or baxi platinum. Please call if you want a free quote

Thank you

Scott

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Update - tried one last time with the iso valves - this time they worked, not sure if BG did something to them... so we do have a leak.

 

Anyway, capped off the dining room, no joy, then this morning took up a floorboard in the living room. Pretty jammy, instantly found a pipe sitting on the ground in a puddle of water - lifted it and found a pin hole spraying out a 1mm jet of water downwards. :)

 

So end result, PITA, but we did get a new heat exchanger for free (if you ignore the £12/month we've paid for the cover for the past 3 years) :)

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Can anyone recommend a good registered plumber to replace a central heating boiler/system

 

Thanks

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