Glowworm Flexicom 30CX Boiler losing pressure

[mcmoby69]

a job is only simple if you know what you are doing. only you know how handy you are with your hands. isolate the boiler , drain down and replace away.

several leaks on a system will produce a drop in pressure. how much ? impossible to tell. eliminate them one by one, eventually you will get there.

 

[Steve1138]

I am pretty confident, the only thing that was putting me off was that everywhere I looked it was saying that you should get a professional in to drain a sealed system as things can go wrong.

f it really is as simple as closing the flow and return valves on the boiler, draining the system, changing the valves and then topping the system back up using the filling loop then I will give it a go.

Is there anything else that I should do / consider before going for it or is the above it?

I have a stop cock on the heating system located in the bathroom, I have had this closed for the last couple of days so that we could turn the heating off at the boiler without the pressure dropping now that the weather is getting warmer and the pressure has remained steady. Will it be ok to drain the system with just this valve close or should I use the flow return valves on the boiler itself?

Thanks again.

 

[Steve1138]

I'm planning on going for it and trying to change all valves on the radiators today to be safe. I'm going to replace the TRVs for standard wheel lock valves and fit lockshield valves to the other sides.

Before I do is anyone able to confirm if the process in my post above is correct or should I do anything else / different?

I've read I should also open all of the bleed valves as it drains but wont this send water shooting out of these valves temporarily?

Its a sealed system if that makes any difference?

Thanks

 

[mcmoby69]

drain from the lowest point of the system. when it stops open the bleed vents on the highest rads then the lowest rads.

then change the valves, you will still get some water out of each rad and it will be dirty so watch your walls and carpets. close all bleed vents and then refill. check for leaks and good luck!

 

[Steve1138]

Thanks, I've just about done it now, taken the best part of the day!

I'm stuck on the last bit now, trying to add inhibitor.

Ive got a cartridge gun inhibitor and have removed a bleed valve from a radiator to squeeze the gel into but all thats happening is that its oozing straight back out of the radiator every time I pull the trigger.

Am i doing something wrong?

 

[mcmoby69]

have you got a towel rad? might be easier. those gun things are crap.
try taking the plug out of the opposite end and see if that helps.

failing that whip a pipe off the bottom of a valve and squeeze it in there..

 

[Steve1138]

Nah, not got a towel rail.

Will it be ok just to squirt it staringht into the pipe coming out of the floor instead if I remove the new TR again?

 

[mcmoby69]

should be, i dont use it myself after the first experience. its only going to be diluted by the water and pumped round ths sytem anyway. shouldnt make any difference how it gets in there.

 

[Steve1138]

Well I left it at 1.5bar last night with the CH off at the boiler, woke up this morning and down to 0.5.

Guess I wasted a day yesterday and its something more serious!

I bled the rads again this morning though and a couple of them had air in them again, can air pockets working there way around the system cause the pressure to drop or was there most likely air as the water had leaked out somewhere?

 

[mcmoby69]

boilers sometimes hav an automatic air valve, which does what it says on the tin. repressurise and see what happens. you may just have lost air in the system.

 

[Steve1138]

But would air in the rads cause the system pressure to drop?

 

[mcmoby69]

did you run the central heating last night? if you then turned it off and the pressure was 1.5 bar, it was 1.5 bar because it was hot, as the heating cooled over night it loses pressure because the central heating water contracts when it cools, giving a possible reason for the apparent pressure loss.

 

[Steve1138]

Nah, had the central heating off at the boiler when I filled the system up to 1.5 after replacing the TRVs and left it off overnight. In the morning it was at 0.5. I topped it back upto 1.5 and went to bleed the rads again and that's when I found more air in 2 of them.

Bled them until water came out and the boiler was still showing 1.5. As of now it is currently at 0.6.

Today though, putting my ear to the wall in the en-suite bathroom, I can hear a lot of water trickling somewhere behind it. Only problem is that I live in a second floor flat and I have no idea what is behind this wall so it could be communal pipes but it could also be the source of the leak. Got no idea how to find out what's behind the wall.

 

[mcmoby69]

fill the system to 1.5 bar, turn all the stats up and turn the boiler on to central heating. after 1/2 hr feel the blow off pipe, is it warm/hot, it will be hot near the boiler but should not be hot along the length of it.

can you see the end of it or does it disappear into that pipe box where you can hear running water?

 

[Steve1138]

Had an unexpected development, I thought I would do the boiler isolation test again just to see what happened so I topped the boiler up to 1.5bar whilst it was cold, closed the flow and return valves and went to work for the day. When I came home it had dropped to 0.2!

The first time I did this test the pressure didn't drop whilst the boiler was isolated so to be certain I opened the flow and return valves again, topped it back up to 1.5 and closed the flow / return valves. I left it overnight and this morning it had gone back down to 0.6.

This seems to indicate that the problem might be with the boiler after all? not sure why it didn't happen the first time I did this test a few weeks ago though.

Anyway as the boiler is still under warranty I have called Glowworm out for a third time, they are due to come tomorrow so hopefully they will find something this time!