DIY Doctor UK DIY Forums

:x
I just wanted a second opinion really. My combi boiler started losing pressure last year, it would go down to zero maybe once a month, then once a week, but now (the last two weeks), i refill in the morning and literally an hour later it is back to zero again.
I KNOW i have a leak!! I have looked everywhere above floor-level as i have laminate flooring everywhere and it will be a nightmare to pull it all up as i have no idea which pipe it might be leaking from.
Ive checked all the valves and the outside pipe and cant see any water.
I dont think it is upstairs as i would see the water on the ceilings so it must be downstairs somewhere.
One gas engineer recommended putting Fernox sealer in the system, but someone else has said it can clog the pump??
Another piece of advice was to chop out my airbrick and see if i can see the pipes that are in the front room and see if any water is there.....
I used a 'damp detector' on the floors downstairs to see if it would pick up any thing, but i dont think it could get a reading through the laminate.
But the reading did shoot through the roof when i put it on the floorboard nearest the pipe work at the bottom of the boiler.
Any suggestions on the right way to go about this??? i am really worried that the boiler is going to blow up!! Plus i am worried about using hot water now!
Thanks very much.

Have you checked the pressure relief pipe? A godd way to do this is secure a plastic bag around the pipe outside - if it fills with water the pressure relief valve is faulty.

Other than that there is a leak some where and sounds like under the boiler might be a good place to start. Hot water will continue to work so long as you keep refilling. If its been going on as long as you say I would have thought there would be some evidence by now.

[quote="gkelly"]:x
I just wanted a second opinion really. My combi boiler started losing pressure last year, it would go down to zero maybe once a month, then once a week, but now (the last two weeks), i refill in the morning and literally an hour later it is back to zero again.
I KNOW i have a leak!! I have looked everywhere above floor-level as i have laminate flooring everywhere and it will be a nightmare to pull it all up as i have no idea which pipe it might be leaking from.
Ive checked all the valves and the outside pipe and cant see any water.
I dont think it is upstairs as i would see the water on the ceilings so it must be downstairs somewhere.
One gas engineer recommended putting Fernox sealer in the system, but someone else has said it can clog the pump??
Another piece of advice was to chop out my airbrick and see if i can see the pipes that are in the front room and see if any water is there.....
I used a 'damp detector' on the floors downstairs to see if it would pick up any thing, but i dont think it could get a reading through the laminate.
But the reading did shoot through the roof when i put it on the floorboard nearest the pipe work at the bottom of the boiler.
Any suggestions on the right way to go about this??? i am really worried that the boiler is going to blow up!! Plus i am worried about using hot water now!
Thanks very much.[/quote]

if your pipes are going down the wall from the boiler then the leak could be under the floor and that is why you have not seen any water. the leak sealer is a good recommendation as i use it on residential and commercial systems and i have not been called back for a leak or to replace a pump. that would be the cheapest option to repair the leak and once it has sealed the leak you can always empty your system and flush it all out the leak would not break down as it hardens on contact with the air

There is def no leak from the pressure vessel on the outside wall - i did the whole plastic bag trick - no water!
I pulled up one floorboard in the boiler room, to see the pipes that lead directly down from the boiler - no water....
So the leak is somewhere under my laminate floor in any of the 3 rooms downstairs - great.
I will try the sealant i think - unless anyone knows any easy way of getting up the laminate and the floorboards without causing havoc???

use the leak sealant. It is a lot cheaper than ripping up your flooring

:D
In the end i did have to take up my laminate as i could smell a 'damp' smell and when we finally looked, there was a little lake under my floorboards. So there was the leak! Every time we filled the pressure back up on the boiler, sure enough - the water would just come spraying back out of a joint on the pipework (under the floor).
So we got that repaired - simple job really.

Now the pressure is abit eratic - so i think its the presure valve as i can see alot of water on the floor outside coming from the pressure relief pipe - is this correct??

what do you mean by eratic ?

if the boiler pressure is rising when the heating is on and there's water coming out of the pressure relief valve then it sounds like a problem with the pressure vessel. May need re-pressurising or renewing.

Yes, it does rise quite alot when the heating comes on and then is back to zero when its off.

sounds like the pressure vessel is the problem.