Loss of boiler pressure

[archaeologist]

Have seen lots of posts on the topic and can see its a common problem. Our boiler is continually losing pressure at the rate of about O.5 bar a week. It loses a lot more if the heating comes on and decays to less than 0.5 bar in a day. When it reaches less than 0.5 bar the boiler trips and then no hot water either. The boiler is a Worcester and is less than 5 years old. It has been checked by a qualified engineer and is fine. The PRV pipe outside is dry. I am expecting the worst as we cannot see any visible leaks. We live in a bungalow with solid floors and wooden coverings. There are no obvious damp patches but who knows what lurks beneath. To avoid a floor demolition derby if it proves necessary I was considering taking on a professional leak detection outfit using gas sniffing etc. They want around £500 to do the tests and produce a full report. My question is are there any other cheaper tests that should be done first and if we do go for full leak detection science - are they successful?

Many thanks for your help folks :smiley2:

 

[Billy Bob Bob]

you just need a plumber or gas engineer who knows what there doing not some BS leak detection scammers,there are various ways a professional can prove if its the boiler at fault or the system its self post your details in the find a plumber part of the forum

 

[archaeologist]

Many thanks gasman. We know the boiler is OK - it was checked out by a professional who decreed that the problem leak is else where. The question I have is can it's exact location be found more easily than leak detection specialists? Are all these people scammers?

 

[Simon F]

hello and welcome along,
is the condensate pipe dripping when the boiler is not in use?
simple test to determine if the leak is boiler related or pipe work, turn off controls so the boiler cannot be used and close the taps on the flow and return pipes, make a note of the pressure ( put it up a bit to aid the test ) and monitor over night if there is a drop the issue is within the boiler if no drop then look at the pipes ( assuming the pressure dial is in the boiler )
then call the plumber to fix it

 

[archaeologist]

Thanks Simon. The condensate pipe ( think thats the one) had a balloon put over it with no problem in evidence. Engineer visiting tomorrow so will suggest your advice but hoping that the first engineer had this covered....maybe not.

 

[diamondgas]

Never heard of a professional leak detection outfit that sniffs out water leaks archaeologist How would they? Maybe put something radioactive in the system then detect where the leak concentrate is?? That'd work actually!!! lol

Question what you're getting for your money or pay for someone to actually inspect your system and let you know what is wrong!

 

[archaeologist]

Never heard of a professional leak detection outfit that sniffs out water leaks archaeologist How would they? Maybe put something radioactive in the system then detect where the leak concentrate is?? That'd work actually!!! lol

Question what you're getting for your money or pay for someone to actually inspect your system and let you know what is wrong!

Hi Diamond gas, thanks for your reply. I am led to believe we know what is wrong. There is a leak somewhere that is causing the pressure to drop. The critical issue then I am told is to find the leak accurately and with the minimum of destruction. As I understand it they drain the system and then pressurise it with Nitrogen, 2% hydrogen (insufficient H[SUB]2[/SUB] to be flammable), then sniff for hydrogen. The hydrogen molecule is very small and therefore will find any leaks, pin-holes included, and the point of highest concentration is the source of the leak. They can also use infra red and acoustic techniques.

 

[diamondgas]

Hi Diamond gas, thanks for your reply. I am led to believe we know what is wrong. There is a leak somewhere that is causing the pressure to drop. The critical issue then I am told is to find the leak accurately and with the minimum of destruction. As I understand it they drain the system and then pressurise it with Nitrogen, 2% hydrogen (insufficient H[SUB]2[/SUB] to be flammable), then sniff for hydrogen. The hydrogen molecule is very small and therefore will find any leaks, pin-holes included, and the point of highest concentration is the source of the leak. They can also use infra red and acoustic techniques.

Hmmmm! That sounds interesting and in theory would work. I hope it proves successful for you. Have you tried a leak sealer. by-the-way?

 

[archaeologist]

Hmmmm! That sounds interesting and in theory would work. I hope it proves successful for you. Have you tried a leak sealer. by-the-way?

Thanks Diamond gas. Haven't tried a leak sealer yet. Can it cause other problems? :thinking: Always worries me when it doesn't address the root cause as such, feels like a shotgun when a rifle is needed if you get my drift. No doubt muuuuuch cheaper, and if there are no side effects maybe worth a go. Thanks for the thought.

 

[diamondgas]

Here's a link to Fernox web site Leak Sealer F4 Express

I've used it on several occasions and haven't heard of any side effects. Give the manufacturers an email for more info archeologist. They'd be the best to advise you on your concerns IMO

To be honest if you have pipes buried in concrete a repair will be a nightmare even if you pinpoint the whereabouts of the leak. You have to lift quite a bit of concrete to get in, cut and repair. If the pipes aren't protected then you'd be better off looking at replacing them because of the likelihood of the whole lot being compromised ...all depends on how well they're protected against corrosion ?

 

[Koogatubac]

Im with diamond, try a few methods before you get the expensive 'leak detection team', if they do find it, you'll have to pay for a plumber to fix the leak which will be another £100+. Leak sealer, has worked wonders for all of us good luck

 

[archaeologist]

Here's a link to Fernox web site Leak Sealer F4 Express

I've used it on several occasions and haven't heard of any side effects. Give the manufacturers an email for more info archeologist. They'd be the best to advise you on your concerns IMO

To be honest if you have pipes buried in concrete a repair will be a nightmare even if you pinpoint the whereabouts of the leak. You have to lift quite a bit of concrete to get in, cut and repair. If the pipes aren't protected then you'd be better off looking at replacing them because of the likelihood of the whole lot being compromised ...all depends on how well they're protected against corrosion ?

Ta for the link. At this stage hopeful that the pipe is properly wrapped or in sand, if not we are in big trouble for the future. As a worst case scenario as a bungalow will have to re-pipe from above the lot from above!! Here goes the life savings!!

 

[Piper Phillip]

Must appreciate it.

 

[Koogatubac]

Arch, surely your house insurance could payout if it came to worst situation? If the pipe is in concrete it should be plastic coated or denso'ed. I also add insulation to the pipe, heard any problems back keep us posted with your progress

 

[archaeologist]

Arch, surely your house insurance could payout if it came to worst situation? If the pipe is in concrete it should be plastic coated or denso'ed. I also add insulation to the pipe, heard any problems back keep us posted with your progress

Checking that angle at the moment thanks Koogatubac. The engineer came this morning. Checked all the rads and visible pipework no problem found. He has locked off the CH hot and cold return on the boiler to pressure test for a week. If it proves to be the pipework he is going to run the CH, wack the pressure up and check again for leaks. If no joy then domesday scenario beckons....

 

[Koogatubac]

Hopefully the PRV will be at fault (steady drip, not set correct) fault at the pressure vessel? These been checked?

 

[archaeologist]

Unfortunately yes.

 

[Mike Jackson]

If the boiler proves to be leak free and the system is leaking don't waste your money looking for the leak under a solid floor. If it's gone in one place it's likely to fail elsewhere shortly. Just bite the bullet and re pipe from above. You'll end up doing it that way anyway after you've dug up the floor 3 or 4 times.

 

[Centralheatking]

I think the leak detection method is no good and expensive. As you say the boiler is fine so its got to be the pipes or the rads. I would for a leak of this volume
1.turn off the feed and rtn to bolier 2.switch off mains cold to boiler 3. close all lockshields and
rad valves on rads. Then I would fill the pipe system to as higher pressure as your mains water will
go and SEE WHAT HAPPENS - something somewhere will give and your leak/s will id themselves.

4. Have a hose witha jubillee clip on the mt cock to let the wet stuff out pronto if you need to.
5. You could pour some dye into the filling loop at 0 pressure and then crank it up.


You might make a mess but it alot less than diggin up everywhere - if your in north
west we will come and do it 4 u centralheatking

 

[archaeologist]

Thanks Centralheatking
The boiler was set at 1 bar and out and in feed closed off. It has been on test like this for a week and the expectation was fhat the pressure would not shift. However the engineer is due tomorrow and the pressure has dropped by half a bar. We are hopeful this is good or at least better news and there is something dropping the pressure in the boiler that can be mended easily. If there was no pressure drop the plan was to do something along the lines you have suggested. We are currently building the ark just in case. Many thanks for your useful suggestions and the offer of getting involved, but we are in the East. :smile:

 

[Centralheatking]

Do let us all know what ur prob really was and how u sorted it please

centralheatking

 

[archaeologist]

Will do. After a variety of tests the conclusion to date from the plumber is that its a small leak in the boiler heat exchanger and may not be a leak in the pipework to the rads (Whoopee if so). The heat exchanger is going to be replaced Monday next week so will hopefully find out shortly after this if he is right.

 

[archaeologist]

At the conclusion of all the tests the culprit was confirmed as the boiler. Apparently if there is a small leak in the heat exchanger the watery evidence can evaporate away leaving no evidence of the problem. To their credit Gasway the contract engineers replaced the heat exchanger without any quibbles. This has been done for a fortnight now. The heating has been on for a session and the boiler on permanently serving the hot water. The pressure has been rock solid at 1 bar throughout. Hope its not famous last words when it all has to work a bit harder, but it looks like the heat exchanger was to blame and we dont have to go chasing expensive underfloor leaks! My thanks to the plumbing Gods, and to all you guys who have offered advice and learned comment :hurray: