A bit of a dilemma with existing boiler installation!!!

6 Mar 2008
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United Kingdom
I’m looking for some advice regards a boiler that was installed in my house 2.5yrs ago.
The boiler is an Vaillant Ecotec Exclusive and the house has 4 bedrooms, 1 bathroom, 2 ensuite shower rooms and a gas hob.
When we bought the house as a new build (built by a very small time developer from other side of the country), the gas engineer commissioned the system and we were issued with a Corgi certificate soon after completion. Immediately I took out a British Gas homecare agreement and on subsequent yearly checks, the BG engineers have pointed out that the gas pressure feed is a couple of mBar lower than the legal requirement…although they all said it wasn’t too much to worry about and that my boiler will still function and will be serviced. Within the last 8 months our boiler developed a fault and the pump was replaced. We then began to hear a loud noise from the pump when the hot water demand switched on and off (like water hammer sound). British gas came out again and the engineer called his mate who is a Vaillant engineer. He replaced the pump again and told me that it is a fancy modulating pump on these systems and that if the problem arose again (dodgy batch of pumps? Because it was fine until the first time they changed it) they would be calling out Vaillant as it still was within their warranty. He then informed me that his ‘Vaillant mate’ said he would condemn our system as unsafe due to the low pressure and isolate it. BG engineer pointed out that there was a 15mm gas pipe going into the boiler and that this was the problem. I decided to check from the meter and found that it is 22mm up till the point where the gas pipe drops down to the boiler from the ceiling above it (the gas pipe runs down behind the boiler and I’m sure there wouldn’t have been enough depth for a 22mm…so it looks like the installer may have decided to reduce the size before dropping down…which means a run of somewhere between 1 to 1.5m of 15mm). The BG engineers reply was simply “maybe he should have installed 28mm”.
I’m now in a dilemma, as the noise fault started not too long after the pump was replaced and is getting noisier to the point where it was at when I last got it replaced.
I’m concerned that I am going to have my boiler switched off and am unsure as to where I stand with regards to contacting the installer that commissioned this installation so long ago (the BG engineer reckons he should still have to put the work right?). The installer didn’t work for me; he was employed by the house builder, so where do I start? Also, since the pipe runs through a section of ceiling, if the pipe was to be replaced, I can only see 2 options for replacing the lot, 1) A hole in the ceiling to access the elbow that drops down to the boiler, or 2) Go in from the floor above, which is fully boarded and Karndean flooring.
The majority of the 22mm run from the meter runs round two walls of my double garage (at least 8m run with a couple of bends). If I could somehow find a way of getting the installer to come back, would it help if at least the majority run of the pipe was increased to 28mm (then there would be @ 1.5m of 22m and @1.5m of 15mm to the boiler)? I realise that calculations would need to be done, but does it seem feasible that this could give me the extra couple of mBar I need to make it compliant?
Finally (phew!!!)…how can I be sure that BG are supplying enough pressure in the first place? The development (11 detached houses) is new and I know that less than 2 year back they were digging up the road at the entrance to our estate to do some work to try and increase the pressure as it was low then.
Soory for the length of the post, but I thought more detail may help with any advice (which I would most gratefully accept)!
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are we talking about standing pressure at the boiler here if we are the boiler should be no monre than 1mb less that what is found at the meter if it is the boiler shouldnt of been turned on in the first place.but most boilers can work at very low pressures now i fitted a baxi that could work at as little as 10mb insted of being around 19-23mb so i wouldnt see this as a problem. the noice is a strange one. next bit :) i dont know if they can condemn (ID) your boiler as it isnt dangerous its just wrong they might (AR) "at risk" it and just switch it off at the gas tap going to it. if i was you i would ring the person that build the house see what cover he had on it insurance or whatever as this pipe was wrong from the start if it wasnt the builder himself that fitter it ask for the gas fitters details or ring gas safe to look up your boiler and see if they can give you them this might make the builder or gas fitter fix the problem cause it is a workmanship fault * bad pipesizing* .if nothing happens get a gas fitter to change the pipe to 22mm or get him to pipe calculate and fix the pipework you may need some 28mm from the meter to the boiler reducing down to 22mm near the boiler*this could be a few hundred pounds as its a pain of a job fixing other peoples work plus 28mm pipe costs alot* if that doesnt stop the noice call bg out and see what they say then SIMPLES :)
To the OP...

I am very sorry that you have found yourself in this position.

You bought the house in good faith. The builder got a half baked installer but thats not your problem. Contact him and ask him to replace the 15mm section at his cost. If he refuses complain to Gas Safe and they will issue a defects notice.

When Gas Safe come to inspect they will measure the pressure at the meter and the boiler. All engineers should do that but a lot are lazy as you have seen.

It sounds as if you have a dirty system wearing the pump bearings. What colour is the water?

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are we talking about standing pressure at the boiler here if we are the boiler should be no monre than 1mb less that what is found at the meter if it is the boiler shouldnt of been turned on in the first place.

you sure about that :rolleyes:

thats what gas safe told me :) and potterton and baxi and a few others first thing they say is whats the standing pressure and meter and boiler cause if it is more than 1mb they say its a pipe sizing fault straight away.
Except for short lengths to pass RSJ's or other difficult bending situations, the cost of tracpipe is prohibitive for competitive installations.

I would expect the pressure loss to be much higher than copper for a similar size of pipe too.

Are you just advertising the product?

I think your getting your standing and working pressures confused, standing pressure means nothing more than a presence of gas and it will be the same throughout the installation.
I'm a cynic and I know nothing about gas pipework, but it does strike me as suspicious that both those proclaiming so loudly about this product are brand new users to these forums.
It sounds as if you have a dirty system wearing the pump bearings. What colour is the water?


The water in the system is clear....when we first had what was thought to be either a pump or flow sensor problem, the engineer was quoting prices for a power flush and spiraflow....when he changed the pump, the water drained out and he was shocked to find it was clear :)
The next time we got a boiler fault, which was a matter of a few months later, they changed the pump again and this new pump immediately made the rumbling noise when starting and stopping. Thats when they talked to the Vaillant engineer and found that there was an issue with these pumps (apparently the fix would be to convert it to a set speed pump and avoid the low speed running when modulating).
WTF has a badly designed and utilized pump by a manufacturer who are obviously embarrassed, got to do with the "gas" pressure, which is only a couple of Mb down, which isn't even classed as at risk. they are just distracting you re the actual problem, which is the pump.

Also you paid for a more expensive modulating pump in your boiler, all advertised as the best blah blah blah, so don't let them fob you off with a standard cheap single speed just for a quick fix, you want what you "paid for", a modulating pump that works, cheeky sods.
I have read some other threads (on here and other forums) and I'm now not sure there is a problem with pipe sizing! Others seem to have much longer and complex feeds with same pipe sizing and still achieve the pressure drop.
How easy is it to calculate? I have an Vaillant Ecotec 838 (38KW) and I have measured my pipe runs as follows:
22m for a length of 12.5m. This includes 4 x 90 deg bends (2 are fittings and 2 are reasonably wide radius pipe bends.
The pipe then reduces to 15mm and drops down to the boiler, I would say no longer than @1.4m in total including 1 slight dog-leg and 2 x 90 deg fittings to allow it to loop back up into the boiler.
Another 15mm pipe branches off to our gas hob...we don't have a gas fire or any other gas appliances.

I have checked back on service reports and found that they usually tick a box saying it is not to current standards...when they have had to go away and return the next day with parts, I noticed that they will tick the 'at risk' box then, but return it to 'not to current standards ,when repaired.

They always recommend the piping may be too small...even though none of them have actually eyeballed the pipe run which can be seen clipped around garage roof for the most part.

I now wonder if this slightly lower gas pressure at the boiler (which causes them to class as 'not to current standards') actually means the Vaillant engineer has the right to switch it off and report to Gas safe?
I feel that the BG engineer and his pal are being quite awkward...perhaps so he doesn't have to come back again and resolve a problem he has failed to do so twice (and look bad to his bosses)?

I have tried to contact the installer via the vendor, but no reply yet. If I could be sure that the pipework was suitable for my installation, I would then be calling B Gas and asking what the actual supply pressure is (never seen them check at the meter)...then I would be able to call out Vaillant undr their 3 yr warrany without the worry of 'his vaillant Engineer mate' turning up and carrying out his threat.

This is doing my head in :mad:

Cheers for the replies so far ;)
As I said, the gas pipe issue is fok all to do with a crap pump, the gas pipe issue is a smokescreen.
Get someone to check the working pressure - not standing pressure - at the gas valve inlet inside the boiler. As long as that satisfies the manufacturer's requirements, all is well.

Certainly, there should not be more than 1mbar drop through the pipework, but the boiler manufacturer specifies the pressure required at the boiler.

Your pump noise is nothing to do with the gas pressure.
Not a chance you will have enough gas at your boiler with what you describe. should have really been in 28mm 95% of the way to your boiler.

In my opinion, the Manuf. are well within their rights to suspend your warranty if your installer has not kept up his end of the bargain by installing the boiler as they ask. Why should I bother my arse to install 28mm all the way to the boiler with the extra costs involved if some monkey can just undersize it or use the existing supply and Vaillant say ' ok no worries '.

The sooner the public wake up to the fact that all installers who hold the same quals are not equal, the better for all of us.

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