Pressure problems on a Gloworm 30cxi boiler

[vegasgo]

We had a Gloworm 30Cxi condensing combination boiler installed 6 years ago, with new rads and 50% new pipe work.

Ever since its always had a pressure issue, but topping it up once in a while it all that has been needed, apart from a couple of small pressure-related repair jobs.

Now, it has all gone belly up. The pressure was lost again and we couldn’t get it back. Engineer has fitted new expansion vessel and divertor vale, cleaned some other bits, but it still doesn’t work for long. The pressure drops to zero within the hour. Fill it back up, and it jumps from 0 to 0.9 immediately, goes up more, than goes down again.

Engineer said the heat exchange is dirty and the system needs a power flush with sealant. It could be air-blocks somewhere, but probably a leak – nothing is apparent though, rads all checked, no damp issues. The only place where it could be is the under the living room floor, where there is lots of pipework.

So, is it was worth ripping up the floorboards to check for leaks, or go ahead with the power flush and sealant? Have heard power flushes are a bit of a gimmick and don’t want to spend even more money on something that may not work. Any advice gratefully received, thanks.

 

[bobw1956]

Pressurise the boiler to 1.5 bar turn the boiler off, over night,isolate the boiler feed&return,check pressure in the morning to determine the pressure loss is the boiler or the pipework

 

[Whitespirit66]

It's normal for sealed systems to need topping up occasionally. However, the losses you are now getting should be evident.

I think your engineer is clutching at straws, and could have you spending money for no result. As said above, do some detective work, and isolate the boiler on the flow and return valves underneath.

If it's the boiler, could be pressure relief valve. Does anything come out of PRV pipe that goes through wall to outside? Is the new exp. vessel correctly pressurised? See FAQs. Could be pinhole in DHW plate heat exchanger.

If your engineer is struggling, and it is the boiler, I would try someone else. Or, if not, get Glow Worm to do a fixed price repair.

 

[vegasgo]

Thanks guys. I will try the first suggestion and see where we go. When I turn the boiler back on in the morning, do I open the feed and return first?

 

[vegasgo]

Just to add, the engineer did do a pressure test, he isolated the boiler from the rads and pumped them up to 3bar pressure – it dropped 1 bar in minutes.

 

[Whitespirit66]

Therein lie your problem. Down to detective work to find leak.

The living room floor sounds favourite. Could poss leak under here, and you wouldn't know,