Heating problem advice

big_white_dog84

big_white_dog84

big_white_dog84

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Any heating experts in here?

I have a problem with my linea vokera 28 combi boiler losing pressure. For a while the pressure would shoot up when heating, then die to zero when heating switched off. The hot water would also cycle hot to cold when in the shower. I have cover with the aa and they came out and changed the expansion vessel and pressure relief valve. This solved the issue of the rise in pressure and the hot to cold fluctuation, but the pressure drop still happens. I can top it up to 1.5 bar and it holds there nicely for a long time, including having showers. It holds fine when the heating is on, but after I switch the heating off the pressure drops to almost zero over approx half an hour. Aa came back out and changed the pressure relief valve again ( some water leaking from outside pipe) and changed another part - a sort of barrel shaped brass component. However he left before he could see that the problem was still there.

Can anyone offer any advice before I get the aa out again and waste another half day off work?

I have checked all radiator fittings and no obvious leaks. Left tissue paper at all fittings overnight and all were dry in the morning.

Worst case scenario is a leak in the pipe under the kitchen floor as we have just spent a fortune on karndean flooring. I'm willing to change the boiler as long as I know that won't be a couple of thousand wasted.

Help?
 
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i know they've changed the PRV but just make sure its not leaking any water outside through that pipe..

a pressure drop from 1.5 bar within 30 minutes is a big one.. so if its not the boiler it'll be a leak under the floor on the ground floor, obviously as if it was upstairs it would come through the ceiling.


is their a crawl space? if not you'll probably have to lift the floors, start with carpeted floors first..

leak sealer also is pointless on such a big leak.. also make sure the boiler doesnt leak internally before lifting floors..
 
It sounds like the pressure vessel. I know you've had it changed but the new one could be faulty, the signs are the pressure relief pipe going to the outside dripping and the pressure gauge going up and down. One way to check if its the pressure vessel is to locate the valve on it that looks like a tyre valve and press it in, if water comes out of the valve then the pressure vessel is faulty. Ooops it looks like I didn't read what you said properly. Maybe try leak sealer like others have said.
 
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The_One said:
doesnt sound like the vessel at all
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I did say I miss read what op had written. If it was still dripping from the relief pipe then I would definitely check the pressure vessel. If its a bad leak then leak sealer won't help either, as Mickie has said. I only use it if the pressure drops over a couple of days
 
Thanks for the replies. If I had a leak then I would have thought the pressure would drop at all times, not just after the heating switches off. I could go through and top it up now and it would hold indefinitely until after the heating switches off next time.
 
big_white_dog84 said:
Thanks for the replies. If I had a leak then I would have thought the pressure would drop at all times, not just after the heating switches off. I could go through and top it up now and it would hold indefinitely until after the heating switches off next time.
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Is there any drips coming out of the relief pipe that go's from the boiler to the outside of the building
 
No drips any more since the aa changed the prv for the 2nd time. Pressure also no longer dying to zero, now stopping at about 0.2 which is a bit strange. When the heating comes on it rises itself to 1 and runs fine. Hot water cycling hot to cold sometime, but not all the time. Nightmare.

On the plus side I have had a look under the house and there seems to be a nice warren of crawl- space, so I now have a task for the weekend to get under there and look for leaks.
 
That is a bit strange, if you had a leak you thought it would drop to zero. You never know, leak sealer might be able to sort it for you. Good luck :)
 
might not be as bad as we thought..

some things just leak once they've heated and expanded enough to start up the leak and seal back up once its cooled down
 
Google has suggested the heating / expanding / leaking thing. In a way that makes it worse as it will be very difficult to find. I'm assuming if that was the case then the system is maintaining its own pressure when hot and it is only when switched off it loses its ability to compensate for the leak and the pressure drops until the system cools and contracts to stop the leak?
 
big_white_dog84 said:
Google has suggested the heating / expanding / leaking thing. In a way that makes it worse as it will be very difficult to find. I'm assuming if that was the case then the system is maintaining its own pressure when hot and it is only when switched off it loses its ability to compensate for the leak and the pressure drops until the system cools and contracts to stop the leak?
Click to expand...

Yes that's right. I've seen it when nails have gone through only the top of a copper tube heating pipe, it took 2 years for the leak to start because of expansion and contraction. There was also plastic pipe joined on to it that also had nails through it but wasn't leaking. That was a expensive lesson for the builder who put down the floor, he had to take the ceilings down :D.
 
big_white_dog84 said:
Any heating experts in here?

I have a problem with my linea vokera 28 combi boiler losing pressure. For a while the pressure would shoot up when heating, then die to zero when heating switched off. The hot water would also cycle hot to cold when in the shower. I have cover with the aa and they came out and changed the expansion vessel and pressure relief valve. This solved the issue of the rise in pressure and the hot to cold fluctuation, but the pressure drop still happens. I can top it up to 1.5 bar and it holds there nicely for a long time, including having showers. It holds fine when the heating is on, but after I switch the heating off the pressure drops to almost zero over approx half an hour. Aa came back out and changed the pressure relief valve again ( some water leaking from outside pipe) and changed another part - a sort of barrel shaped brass component. However as usual they bugger off the minute the job is done rather than hanging around for half an hour to find out that the problem was still there.

Can anyone offer any advice before I get the aa out again and waste another half day off work?

I have checked all radiator fittings and no obvious leaks. Left tissue paper at all fittings overnight and all were dry in the morning.

Worst case scenario is a leak in the pipe under the kitchen floor as we have just spent a fortune on karndean flooring. I'm willing to change the boiler as long as I know that won't be a couple of thousand wasted.

Help?
Click to expand...

Hello big_white_dog84, we'd like to look into this for you, please email the details to [email protected] including reference FOR34621. Regards, The AA
 
Thought I should post the outcome, for anyone that is fussed.

Turns out it was a faulty pressure gauge. The pressure wasn't dropping at all. When I was topping it up to what I thought was 1.5 bar it was actually over 3, causing the prv to operate. Finally got this replaced yesterday and this morning was the first time I have woken up to pressure above 1 bar for months. Fingers crossed that's it. I have to say the aa were really good once they finally got their teeth into it - the problem was getting them interested in the first place.
 
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