Boiler pressure dropping & how to find the leak

[Geeky]

Hi All

Looking for some advice. Since I switched the heating back on a few weeks ago, the pressure on my one year old Vaillant Ecotec boiler has been dropping by one tenth of a bar each day - so from 1.5 to 1.4 to 1.3 and so on right down to 0.9 this morning when cold. Pressure rises by a few tenths when the heating is on but then drops again when cold. I can't see anything dripping from the pressure relief valve.

Worst case scenario is a leak under my newly laid laminate floor or behind my newly fitted kitchen cabinets! If this is the case, do any of you have any advice on or experience of leak detection companies? As I understand it, they use gas and thermal imaging to find small leaks without having to pull the whole house apart.

I'm waiting for a plumber/heating engineer to call me back, but in the meantime I'd really appreciate any comments or advice.

Cheers!

 

[Billy Bob Bob]

you cant go looking for leaks really until the expansion vessel has been checked in the boiler wait and see what your installer says

 

[GasMan1983]

If theres no sign of water leaving the pressure relief valve outlet pipe then your expansion vessel is ok, might have a weep from somewhere.

To save you the hassle of taking floors up try some Fernox Leak Sealer.
Turn off the valves of radiator your going to use.
Open the bleed point until no more water is coming out.
Remove the bleed point very carefully as in some cases you will get about 5-10 secs worth of water when its taken off.
pour the leak sealer in and put the bleed point back in.

its worth a shot.

 

[wnjswozo]

agree with gasman1983,but worth getting installer to check exp/vessel/re charge it

 

[Blackcatgas]

Installer to check rad valves etc first. He will sort it.

 

[Geeky]

Thanks everyone - engineer coming next week but spoke to him on the phone and he seems to think it's quite a big leak (tenth of a bar every 24 hours) so I'm not sure if leak sealer would do the trick. PRV is dry whenever I check it. Engineer said he will check boiler first anyway. Meanwhile, have found today there is quite a lot of air in the system, so have bled rads and will see if this makes a difference.

If there is a leak, it is likely to be under my new laminate floor so I was wondering about those leak detector companies. Would be interested to hear your views on these - just in case ...

 

[GasMan1983]

A tenth of a bar could be a tear drop leak. Over 24 hrs that could take away that much pressure. If the pressure drop began in tandem with your new floor then you may be right if nails were used.

I'm not aware of any companies that offer that service, better gettin a heating engineer in to have a look.

Btw if the prv pipe is dry and there is no sign of leakage at the boiler then the expansion vessel is fine, that's a 2 minute job anyway.

Another way of trying to find the leak, keep the heating off for a day as when it's on leaks are less likely to show up as the metal swells under heat tightening connections I.e rad valves. Check bleed points aren't weeping as the newer kind have o-rings which sometimes perish and let water seep.

A long shot I thought of since you mentioned airing the system Is air entrainment. It may be the case that air is being sucked into the pipework and then being vented from auto air vent(if your appliance has one) resulting in what appears to be a "water" leak that is actually air getting in slower than it's being vented from the auto air vent, through a pinhole.

Hope some of that helps.

 

[Geeky]

That's very interesting Gasman83 - thanks - although I don't rate my chances of finding a pinhole, so I'm now hoping it is a water leak. Will update thread when I have some news.

 

[aggis]

Inject fernox leak sealant. Get the aerosol type, makes adding it to system, a simple job.
Connect the adaptor to the filling loop squeeze & job done.

If it was your expansion vessel causing the problem, you'd find when the heating is on the pressure would quickly go upto 3 bar & empty very quickly, not just loose 1 tenth bar

 

[marsaday]

Has the boiler been drained down recently ?

I have just had my vailant moved and the pressure has decreased from 1.6 to 1.1 bar due to air being disbursed. The boiler is now at 1.2 bar and it is staying there now.

it may just be air getting out.

 

[Geeky]

I'm worried about using things like Fernox and will need to check if Vaillant allow this. From what I've read on other threads, it seems to do the trick for some but others say it's a last resort as it might block up the boiler valves. We did have the system drained down in the summer and had an extra rad put in. Problem is, the pressure is not coming to rest at a low point but just continuing to drop - it went down to 0.7 then I caved in and topped it up. Pressure rises when the heating's on but not right up to 3.0 so agree prob not expansion vessel unfortunately, as this would be less hassle to fix than lifting up the blardy floor. There was a lot of air in some of the rads when I bled them last night. Will have another go tonight. Thanks all for your comments - I'll keep you posted.

 

[Geeky]

Well, nice boiler man has just left and the boiler is fine ... which is bad news as it means I have a blardy leak. His opinion was that leak finding companies charge hundreds of pounds and suggested trying Fernox before pulling up the floor. Please reassure me that Fernox will not wreck my boiler.

 

[Dannypipe]

Someone asked you if you any nails/screws had been driven through the floor? When the ply was laid for the laminate floor perhaps?

What can happen with a nail, screw is that if they hit a pipe, they leak, but not always terribly. However as the screw rusts and degrades, the leak worsens. Fernox leak sealant will struggle to sort this type of leak.

Anyway, you've not got much to lose. I use Fernox leak sealant as a 'last resort' as you mentioned earlier. I would not hesitate to try it if I was you.

Danny

 

[Dannypipe]

Oh and those leak detection companies often fill the pipes with a gas, that will show up leaks. I watched a programme about it. very clever business, but at the end of the day, if you do have a leak under the floor, it's coming up! So give the Fernox a try and see how you get on.

 

[Geeky]

Cheers Danny. The builder whose guys laid the floor is coming round next week so will discuss possibility of nail through pipe with him. As the gas meter is under the floor we have a small access point and are going to see if we can see anything by hanging down there head first and shining a powerful torch. I might also see if our buildings insurance will pay for a leak tracing company. If we can't find anything without pulling up the floor, will definitely try Fernox.

 

[Centralheatking]

Depending on the layout of the heating system if might be an idea to say blank off part/half of the system - eg upstairs from downstairs or 1 or 2 rads on a longer leg and see if pressure still drops then you could begin to focus on the exact location to tear up.

Or shoot it up with loads of mains pressure with the boiler isolated and see if the leak can be made worse and show its location.

centralheatking

 

[Geeky]

Centralheating, the boiler guy mentioned isolating upstairs from downstairs - sounded like a bit of hassle as it apparently involves cutting and capping off the pipe then presumably having to join them again afterwards ... ? But will mention this to my builder, plus the idea of upping the pressure to identify the leak. Thanks for the tips.

 

[Geeky]

Well here's an update as promised. As the weather got colder and we had the heating on more, the leak got worse and we were topping up every other day. I had my builder put some Fernox SuperConcentrate in and (fingers crossed) it seems to have worked and 2/3 days later the pressure seems to be holding up. If it starts leaking again, by the way, would you put some more Fernox in?

I did ring some leak detection companies - one national company quoted £700 plus VAT plus materials and a London based company just admitted it would be £1000 in all . This is for a small two bed house with only 6 rads, none buried in concrete. Sounds like a good business to be in.

Anyway, my builder reckons if the leak reappears it's only a day's work for him to pull up floors, find and fix leak, and make good - £120 plus materials, so I'm feeling better all round.

Thanks for all your suggestions too which have improved my knowledge and helped me get this sorted.

 

[justlead1]

Hi. Is the new laminate floor fitted over an existing wood board floor? And were any boards nailed or screwed prior to new laminate floor?

 

[Geeky]

Hi Justlead1 - laminate is on hardboard/chipboard - one or two bits were replaced before the laminate was laid. Are you thinking screws through pipes? Someone did suggest this. It's possible, but my builders are pretty good so I'm hoping they wouldn't make this kind of mistake. If the leak comes back and we have to take up the floor, I guess we'll find out ...

 

[justlead1]

Get some pressure testing done before panicking about leaks. Your plumber can isolate expansion vessel, purge any air from system and pressure test. When testing, be aware that temp change has an effect on gauge readings, the longer you can leave it on test the more accurate the results. Good Luck

 

[Geeky]

Get some pressure testing done before panicking about leaks. Your plumber can isolate expansion vessel, purge any air from system and pressure test. When testing, be aware that temp change has an effect on gauge readings, the longer you can leave it on test the more accurate the results. Good Luck

Excuse my ignorance Justlead but what does pressure testing do (if not find leaks)?