Glowworm Flexicom 30CX Boiler losing pressure

[Steve1138]

Ok, I've just been out to check the boilers pressure after leaving it isolated since 2:30 yesterday afternoon and it has dropped from 1.8 to 1.6.

Is this normal?

Surely at that rate it would be at 0.0 within a few days?

I have not opened it back up to the rest of the system yet.

 

[mickyg]

i wouldnt read too much into a 0.2 difference. Its not significant enough. Didnt you say it dropped to 0 overnight? Leave it as long as you can and then see what happens

 

[Kev F]

Forget the boiler for now, I'd be sorting the rads out first, run as normal and see what happens

 

[Steve1138]

It would usually drop down to between 0.3 and 0.0 overnight, basically low enough that the boiler would not work in the morning and would need topping up. Then by the time I had got back from work in the evening it would be back down to around 0.3 / 0.0.

This has been happening for months though and we can go for weeks at a time without it happening and then it will randomly come back.

Also we have not found water anywhere else and have had no complaints from the people in the flat below us that water is leaking through, hopefully it will be the TRV.

I have reopened the flow and return valves from the boiler just now (the central heating is still off at the boiler though) and the pressure immediately dropped from 1.6 to 1.5 but I guess this is normal as the water must have been moving around the system after reopening the valves?

I have left all the radiators off at the valves and I was planning on turning each one on one at a time to see if the pressure drops, is this worth doing?

Either way should I leave the central heating off at the boiler for now?

 

[Kev F]

You will always get a fluctuation of anything up to 0.4 bar so don't worry.

 

[Steve1138]

Ok, so I opened the flow and return valves on the boiler again at about 10:30, was at 1.5 bar.

It's now 12:38 and it has gone down to 0.9 bar. I'm guessing this is too much of a pressure drop in too short a space of time?

The TRVs and lock shield (I think that's what they are called) valves on the rads are still closed at the moment. Could the potential leaky TRV I found on the bedroom rad still cause a pressure drop even if all valves on all the rads were closed?

 

[Steve1138]

3:30pm and the pressure is now 0.6 bar.

 

[mickyg]

well that seems to prove its the system then as it was fine in the same time period on the boiler. Thats a fair amount of leakage, but the way to approach these things is to rectify each problem as you find them even if possibly not the main culprit. You need to trace as much pipework as possible. If any is buried in concrete flooring you may have some issues on your hands.

 

[Steve1138]

All of the rads are still closed off at each of their 2 valves, should I open these now?

Would the leak in the TRV be enough to cause this kind of pressure drop do you think?

I live in a second floor flat with concrete floors and I'm pretty sure all the pipes run through the floor. As this problem has been there for about 5 months now wouldn't water be visible in our flat or the flat below by now if it was one of the pipes in the floor leaking?

 

[mickyg]

i would have thought that amount of drop would be fairly noticable wherever it is but the trvs that leak should be replaced regardless.

 

[Steve1138]

i would have thought that amount of drop would be fairly noticable wherever it is but the trvs that leak should be replaced regardless.

That's what I thought. Would replacing the TRV be something a complete novice could do or would I be better off getting someone in to look at it?

 

[Kev F]

Id say more of a leak on pipe/rads than valve losing that much. Might need to get someone in

 

[Steve1138]

Thanks all.

I'm going to get someone in next week as it dropped to 0.0 during the day yesterday and when I went to top it up the boiler started making a swooshing sound and I could hear the water filling up in the radiators so it must have been completely empty?

Really hoping it's not a leak in the floor as we are in a second floor flat with concrete floors and have just had new laminate flooring fitted!

 

[Steve1138]

Hi again

Just following on from this, I found a second TRV in the flat with a couple of drops of water coming out by the pin inside the TRV when I took the cap off it.

I'm thinking that 2 potentially leaking TRVs could cause the system to lose pressure?

I have 2 questions:

TRVs seem to be more hassle than they are worth, is there any pros or cons for them compared to normal valves?

Would replacing the TRVs be something a complete plumbing amateur
(ie me) could do or should I get someone in?

Thanks again

 

[Steve1138]

Sorry to bump this but was just hoping someone might be able to help?

Thanks

Steve