Tracking down a central heating system leak

sundin13

Well, here's the update!

I decided after this point to sign up to British Gas Homecare with pipe cover so that they'd fix anything that was wrong. The boiler passed its initial service inspection no problem, and so I waited a few months to raise the pressure issue with them. Earlier this year I called them out as the fan was noisy, and mentioned it then. I was told to 'monitor it', and that if it was under the laminate then there wouldn't be a lot I could do.

Fast forward a bit, and I called them out again to deal with the loss of pressure, and they checked the boiler, PRV and rads and then put leak sealant in and went off on their merry way. Another week passes and I had to call them again, as not only is the pressure gone, but the filling loop tap is broken. I talked to the engineer about the pressure, and he checked everything again but basically said unless I take the floor up to find the leak, they can't help.

So.....tomorrow, the laminate flooring is coming up, as we are moving house and due to complete in a fortnight, and I can't leave the problem to the new owners, it just wouldn't be right.

I'm hoping against all hope that the joiner pulls up two planks, two floorboards and lo and behold, a big puddle on the foundations. And also that the laminate fits back together perfectly (otherwise I'll have to buy a whole new room's worth as I have none spare).

Wish me luck.

S13

sundin13

Oh, and just out of interest as this is a moneysaving board. I've been clearing out paperwork ready to move, and when I put all the receipts for boiler and heating repairs together, I've spent over £1000 on it in five years:eek:. So the new house is getting a new boiler with a warranty the minute it has something wrong with it.

adsi

Hi Sundin, I'd love to know if you fixed the problem after you lifted the laminate floor. I have a similar pressure droping problem in my combi system. The dropping rate is 0.2 bar in 4 days.

sundin13

The short answer I'm afraid, is no.

We took up the laminate, could see no sign of a leak.
We called BG and asked for a service visit while the floor was up. The engineer couldn't see a leak either - said it must be something else. So he went and pumped up the expansion valve to repressurise it.

New laminate floor and fitting = £300 odd.

The pace of pressure loss slowed down for a week or two - then was as bad as ever. I rang BG - almost in tears as we were a week away from moving and I didn't know what to do to resolve the problem. The only thing I could grab onto was that the expansion valve was the problem and needed replacing.

BG engineer and area manager came out, hummed and hahed a bit, then pronounced that there wasn't a problem with the expansion valve. But agreed to refund me £100 for the last two visits anyway.

So that was that - they went back to the line of 'there must be a leak somewhere' - just top it up regularly. And i moved house. And I feel so guilty that I try to avoid shopping locally because I'm convinced I'll run into the people who bought our house and they'll have a go at me about it.

Sorry if that's not the happy ending you were after!!!

S13

adsi

Hi Sundin, I am sorry to hear that you did not manage to solve the leaking problem in your previous house. However, I think I did what you can do in this situation. I hope you are free of the leaking problem in your current house. :beer:

alanobrien

Last year my brother had a leak in his pressurised system. It would loose half the pressure overnight
i.e drop from 1 bar to circa 0.5 bar. I should add at this point he was a corgi registered industrial gas fitter some years ago before he changed jobs and i am a mechanical engineer so we are both practical people.

We tried all the obvious quick tricks like tissue paper on visible joints, zone isolation etc to find the leak but it remained elusive.

I even borrowed a thermal imaging camera from work and we had no end of fun playing with it but still didnt find the leak.

I was just thinking about ultrasonics as a next potential thing to try (ultrasonics are used in pipeline leak detection) then in a lightbulb moment came up with the thought of trying a flourescent dye in the system then looking at the system in the dark under UV light.

It worked a treat, turns out he had 3 duff lockshields, tiny leaks from the o ring stem seals that lit up like a xmas tree under UV light. We replaced the valves, flushed the system and the problem dissapeared.

Its worth mentioning that i suspect boiler manufacturers would frown on this practice even though the dye is perfectly safe (its used in the medical industry). however his boiler was 8 years old so way out of warrenty anyway.

I wouldn't recommend this process unless you know what you are doing but it worked brilliantly for him and if i have a similar problem with my system in the future, i have some of the dye left

frank.hopper

sundin13 wrote: »

So that was that - they went back to the line of 'there must be a leak somewhere' - just top it up regularly.
S13

You did your best! there's nothing more you could have done.

What's interesting is, if the buyer continued with BG homecare they would probably be told the same thing, the day would come when the system would be so sludged up with the constant topping up, BG would be looking for £600 for a power flush.

Ebe_Scrooge

Hmm, new poster, who's first post is promoting their own website ?

Spam, methinks, post reported.

odgeuk

I'm having a similar problem with a 6yr old Baxi Combi. The pressure will drop from 1 bar to almost zero in 4-5 days. I've been topping it up for months.

It seemed to become this bad shortly after I had an engineer out to repair a filling loop which had over-pressurised the boiler due to a faulty valve. Prior to that I had some recollection that I needed to to it up just maybe every 4-5 weeks.

Anyway, the engineer who repaired the filling loop, cleaned and resat the Pressure Release Valve and said to keep an eye on it. I didn't see any water or dampness from the PVR after that but the boiler still continued to lose pressure.

Many months later, I had a new diverter valve fitted, and the secondary heat exchanger cleaned in an Acid bath, to fix a problem with Hot water entering the Heating System (and running intermittent cold through the taps). At the same time I asked the engineer to replace the PVR to see if it fixed the pressure issue. He also checked and pumped up the expansion vessel and stated that as water wasn't coming out of the valve of the Expansion vessel, that the pressure problems were unlikley to be related to a faulty Expansion vessel. (he also said that if it was the Expansion vessel, then eventually, after topping up as much as I had been, it would overpressurise as the water would have nowhere else to go).

Anyway, so here I am, with either a faulty boiler, or a leak under the floor somewhere in my central heating pipes.

I was very concerned to hear that continuous topping up leads to sludge in the system??! I have an inhibitor inline with the water supply to the boiler which I'm told should work for the lifetime of the boiler? The last thing I can afford right now is a Powerflush.....

Myser

Repeated topping up and thus dilution of the concentration of inhibitor already in the system, reduces its effect and eventually can lead to sludge build-up if you do not top up the inhibitor as well.

odgeuk - in your case, as the inhibitor is added inline with the water supply, this shouldn't be a problem. You just have to check that the inhibitor reservoir doesn't get empty!

Many small leaks occur at the radiator valves/TRVs and go undetected because the water evapourates as the radiators heat up.

You may notice some oxidisation on the radiator pipes if they are copper (green staining) and this will give you a clue to leaking valves.

I like the technique alanobrien mentioned with UV dye - although it may invalidate manufacturers' warranties!