My boiler keeps losing pressure

ThisIsWeird

CPFC_79 said:

@ThisIsWeird - it's only a very small rise, it's been on for an hour and it's currently at 1.8.

I'll report back on cold pressure level in the morning as the heating won't be on tonight. 

Yes I mean the pipe that points to the ground....again I will inspect that in the morning

@FreeBear all the pipes in the floor are plastic, they were all replaced two years ago so I would hope no leaks yet! You mention "TRV or lockshield is weeping around a seal or union nut' is this where the rads connect to the pipes? So just inspect all of those and check no leaks?

Thank you both!

1.8 bar should be fine. Keep an eye, and see if it goes significantly higher.
Boilers have a built in safety valve that pops open at 3bar. The system pressure only gets close to this if the EV is faulty, or it's been overfilled. If the valve opens at 3 bar, it dumps the excess system water outside via that pipe. That then means that the sealed system will have less water in it, and the pressure will drop to below what it was when cold again.
In essence, no water at all should be coming out that pipe, not a drop.
And, yes, check every rad valve carefully for signs of leaks. Wee ones may dry as soon as they are created, but should leave evidence such as scale or verdigris.

FreeBear

ThisIsWeird said:

CPFC_79 said:

@ThisIsWeird - so it drops under 1 bar and I get the F.22 warning on the screen. When I top it up I put it to about half way between the bars. Yes I believe it does increase as the heating comes on but I will double check that. Should it be increasing as the heating comes on?

There is a wet patch under the copper pipe so I have strapped a clear plastic bag around as you have suggested. 

One other point to note which might be relevant is that the Egg Timer Symbol (anti cycling mode) seems to activate a lot in winter.....not sure what is normal (how many times a day).
Again this is something I can monitor

'Should' the pressure increase when the system heats up? Not really, because the boiler has an 'Expansion Vessel' inside it, which absorbs the expanding water, and should prevent a significant pressure rise.
A small rise is, however, perfectly normal, and not an issue. It all comes down to how high it goes. Just above 2 bar is usually acceptable, tho' not ideal.

My boiler sits at 1.4 Bar when cold, rising to 1.9 Bar when up to temperature. A bit more than I first expected, and I've bled the system multiple times. Only getting a tiny puff out now, so nothing to worry about.

@FreeBear all the pipes in the floor are plastic, they were all replaced two years ago so I would hope no leaks yet! You mention "TRV or lockshield is weeping around a seal or union nut' is this where the rads connect to the pipes? So just inspect all of those and check no leaks?

Plastic in concrete - Brilliant. No chance of leaks as long as no fittings have also been buried.

Union nuts are indeed the bits that connect the rads to the valves & pipes.

CPFC_79

@FreeBear @ThisIsWeird - morning report. The heating was off all night and when I got up the pressure was 1.5, when the heating came on shortly after it went up to 1.7. The heating has been off for 45 minutes now - I just checked it and the pressure is at 1.0!

Just looked at the bag outside and no water in there yet. 

I will start checking the rads for leaks....anything else I should be doing?

FreeBear

How old is this boiler, and is it still under warranty ?

Going up from 1.5 Bar to 1.7 Bar when running is quite normal and well within the range I would expect. Dropping down to 1 Bar after being off for ~45 mins is not. Assuming no leaks from pipework or radiators, the problem is with the boiler. Unfortunately, to investigate the internals of most gas boilers, you should be Gas Safe registered before removing the outer covers.

CPFC_79

@FreeBear - about 10 years old and not under warranty. I inherited it when I bought the property. 

I found a tiny amount of liquid around one rad valve.....I also have spotted another rad copper valve/pipe has gone green. It's the only one - all the rest look as new, Is that also a sign of a leak?

FreeBear

CPFC_79 said:

@FreeBear - about 10 years old and not under warranty. I inherited it when I bought the property. 

I found a tiny amount of liquid around one rad valve.....I also have spotted another rad copper valve/pipe has gone green. It's the only one - all the rest look as new, Is that also a sign of a leak?

Verdigris (the green stuff on a copper pipe) suggests a small leak and the water is evaporating before it dribbles on to the floor. You also get verdigris appearing around soldered joints that haven't been cleaned fully, but I suspect this isn't likely if you have plastic pipes on the rest of the system.

A small amount of liquid on a radiator valve points to a leak. It is sometimes possible to tighten up the gland nut, but often easier to just replace the valve body - To do so means draining the system down. Once the valve body has been replaced, add a bottle of corrosion inhibitor, refill the system, and bleed all the radiators. If the valve body that has been replaced was a lockshield, the radiator will need to be balanced.

Although the work isn't difficult, it is time consuming. So worth checking all the radiators and replace any valves that looks suspect. You also have opportunity to replace any radiators that have gone rusty or you feel are not big enough for the room.

ThisIsWeird

CPFC_79 said:

I found a tiny amount of liquid around one rad valve.....I also have spotted another rad copper valve/pipe has gone green. It's the only one - all the rest look as new, Is that also a sign of a leak?

Photos of all the culprits, please.

MikeJXE

 Feel the carpet under the radiator to see if it’s wet, place a strip of toilet paper on the floor under each valve that will show any tiny leak

KittenChops

Flugelhorn said:

we have a similar boiler in a flat but was suddenly needing topping up rather more often - plumbers commented that it is actually only a small amount of water each time but that was definitely not right - they muttered about the expansion vessel but that was OK and then they went leak hunting.... there was one, fortunately under the floorboards so "reasonably" accessible and mendable 

Had very similar within the last month or two (but oil boiler) - isolated one radiator, luckily in downstairs loo / smallest room in the house, & pressure has held (now need to sort out replacing that radiator / pipework)