Glowworm Flexicom 30CX Boiler losing pressure

[Steve1138]

Hi

I am having problems with the above boiler rapidly losing pressure in a short space of time (ie 1.7bar to 0.0 overnight)

Have had glowworm tech out twice and he cannot find anything wrong with the boiler, he also did some kind of test to check for leaks in the system but couldn't find anything wrong there either so he was stumped!

I am just trying a test myself to isolate the boiler for a few hours to see if the pressure still drops. I know I have to turn the CH flow and return valves but should I also close the cold water in valve for this test to work? Also does it matte if the power is left on for the boiler?

Some other fault finding I ave done is to check the Rad valves, most of the rads have Drayton TRV-4 valves. If I take the head off and press down on the pin underneath then drops of water come out, is this normal or could faulty rad valves be the cause of the pressure drops?

 

[Kev F]

Water shouldn't come out of the trvs

 

[Steve1138]

Hi

Thanks for the quick reply.

I have just double checked the TRVs and I took the head off one in the bedroom and the valve itself inside was wet.

No more water is coming out now when I push down on the pin though.

Should no water at all, ever come out or is a couple of drops normal?

Thanks again

 

[mickyg]

replace the trvs that are leaking

 

[misterdubya]

Is this following on from a previous topic?

 

[Steve1138]

So any sign of water when taking the head off the TVR could cause the boiler pressure to drop to 0.0?

Is anyone able to advise the correct way to isolate this boiler so that I can rule out a boiler fault causing the pressure drop?

Thanks again

 

[mickyg]

make sure the heating is switched off, close off the 2 isolation valves on the flow and return using an allen key (not a screwdriver), they are the 2 bigger pipes on the far left and right under the boiler.
Leave the boiler for enough time that it would normally lose pressure. If the pressure drops on the boiler then there is a problem with the boiler, if when you reopen the valves the pressure drops then it is on the system.
Whether the trvs are the main reason is neither here nor there, they shouldnt let any water out and should be replaced, so at least rule that out.

 

[Steve1138]

make sure the heating is switched off, close off the 2 isolation valves on the flow and return using an allen key (not a screwdriver), they are the 2 bigger pipes on the far left and right under the boiler.
Leave the boiler for enough time that it would normally lose pressure. If the pressure drops on the boiler then there is a problem with the boiler, if when you reopen the valves the pressure drops then it is on the system.
Whether the trvs are the main reason is neither here nor there, they shouldnt let any water out and should be replaced, so at least rule that out.

Thats great, thanks very much!

Should I turn the power to the boiler off at the wall or just deactivate the heating in the boiler panel? Also does it matter if the cold water inlet is open or closed for this test?

 

[mickyg]

you can leave the power switched on and just deactivate the heating so you can keep an eye on the pressure display. If you turn the heating temperature down on the display past 38C it reverts to OFF. you dont need to worry about the cold water inlet valve and you can continue to use hot water.

 

[Steve1138]

you can leave the power switched on and just deactivate the heating so you can keep an eye on the pressure display. If you turn the heating temperature down on the display past 38C it reverts to OFF. you dont need to worry about the cold water inlet valve and you can continue to use hot water.

Thanks again!

Sorry, just got another few questions as I really want to get to the bottom of this! So a leak in a hot water pipe somewhere wont cause the pressure to drop? Is the pressure only for the heating system?

I had already isolated my boiler in the way you described earlier today, I just wanted to make sure I had done it right. It was at 1.8 when I isolated it and it is now on 1.6 3 hours later. Is there an expected pressure drop tolerance even if the boiler is isolated?

 

[mickyg]

yes its just the pressure in the heating system, i wouldnt read too much into small changes in pressure as this could just be expansion. If its dropping all its pressure overnight like you say then thats what I would be looking for.

 

[Steve1138]

yes its just the pressure in the heating system, i wouldnt read too much into small changes in pressure as this could just be expansion. If its dropping all its pressure overnight like you say then thats what I would be looking for.

Thanks again, restarted the test about 2 and a half hours ago. Set it at 1.8 and it has stayed there so far. I'll leave it isolated overnight and see what it says in the morning.

If it stays at 1.8 all night and then drops in the morning when i open it up again then hopefully the problem is just the TRV in the bedroom.

Would a few drops of water coming out of the TVR be enough to drop the pressure to 0.0 in a few hours?

 

[Kev F]

No but stranger things have happened

 

[Steve1138]

I think the screw in seating that the pin is in (not sure of the technical term) on the trv was not screwed down all the way as I have just found that I could tighten it up a bit, perhaps this is what the pressure was dropping if it had not been tightened up properly.

When I open up the valves on the boiler again in the morning to see if the leak is with the system (If the pressure has not dropped overnight) then should I leave the heating off until the pressure drops or turn it back on for that part of the test?

 

[Kev F]

Turn it on, shouldn't make a differance