Central heating boiler losing pressure (again)

in_my_wellies

Granny_98 said:

in_my_wellies said:

Bendy-House
Many thanks for your detailed description. You have been so helpful to the OP. Thank you! And very interesting 

I had problem with pressure in my BAXI boiler. The engineer said probably the EV but could be another part. He replaced the EV tank but it didn't fix it so came again and replaced the other part. That fixed it. I don't know the name of that but it was relatively cheap (£12?) and I wished he had replaced both in the one visit to save me another £75 call out charge. Fully appreciated it was a good idea to change the EV as it over 17 yrs old. But in one visit! 

Can't you find your bills and have a look LOL! 

No, the bill isn't itemised or detailed

Bendy_House

Granny_98 said:

I switched the heating off, left it a while (2 hours) the pressure dropped (but not to zero) refilled to 1 bar, turned heating & hot water down to minimum then isolated the boiler. Got up at 7.30 & it was all as I left it, as I was about to undo the isolation I decided to video it and had my phone on a stand fixed to reading the dials on the boiler, reversed the isolation and fully expected  the pressure to drop etc if the fault was in the pipework - and nothing happened! I kept videoing in 5 & 10 minute slots (what's that saying "a watched pot never boils" so true!) & nothing. Bendy_house - My plumber sticks a pressure gauge into that black valve, which is why he said it needed replacing in December, so I will phone him Monday if this continues. 

If you repeat this sort of test, please shut the boiler off completely at its mains supply.

Pleased the pressure didn't drop when you reopened the valve.

What I think I'd do in your position - ie when you have doubts about the calibre of the repair fellow - is to first try and determine whether it's a leaking EV. Since your boiler is actually working, I don't see any harm in giving it a few more weeks until a more obvious symptom appears.

If you read and followed my earlier post, IF this is a slowly-leaking EV - and it's the only thing I can think of - then a couple more weeks of pressure drops should expose this. Once the EV has lost enough air so it can no longer function properly, then your pressure readings will indicate a problem; it will start to rise in an obvious way when the CH heats up. Once that happens, you can - with near certainty - tell the fixer to 'fix the bludy EV, proper, like'.

The EV could even be leaking air out the 'tyre' valve - I presume it has a cap on it? In this case, tho', I wouldn't expect 'glug' sounds, or sudden pressure drops, both of which you appear to have. A slowly leaking valve would result in a slowly dropping pressure reading.

I think I'd give it more time until it becomes more obvious.

Once it does go funny, then it's often also seen when the EV's pressure is checked - when the wee pin in the Schrader valve is pressed, you'll often get water coming out too - a sure sign of a bust diaphragm.