Leak from pressurised system

[MickBrown]

My nextdoor neighbour has a pressurised heating system, downstairs the pipes ae in the screed. He keeps losing pressure in the system, he has to repressurise 2 or 3 times a day. it leaks so much that the upstairs radiators drain down occasionally. I went round to check for leaks, I checked all the rads and visible pipework, signs from upstairs and any signs from under the floor. I couldn't find any problems. I checked outside for external drain off points but couldn't find any. He recently had a new boiler fitted, not by me as I'm not gas safe and I'm retired now anyway. After the boiler was fitted the pressure was fine until recently. The guy who fitted the boiler came round and checked that there were no issues with the boiler, he also checked everywhere for leaks and he couldn't find any either. Eventually my neighbour got a specialist leak detection company in. He tracked all the downstairs pipe work with a thermal detector, a sound detector and also another method I can't remember. He spent some considerable time there but couldn't find any signs of a leak.

Can anybody else think of something he could check?

 

[LowGear]

My nextdoor neighbour has a pressurised heating system, downstairs the pipes ae in the screed. He keeps losing pressure in the system, he has to repressurise 2 or 3 times a day. it leaks so much that the upstairs radiators drain down occasionally. I went round to check for leaks, I checked all the rads and visible pipework, signs from upstairs and any signs from under the floor. I couldn't find any problems. I checked outside for external drain off points but couldn't find any. He recently had a new boiler fitted, not by me as I'm not gas safe and I'm retired now anyway. After the boiler was fitted the pressure was fine until recently. The guy who fitted the boiler came round and checked that there were no issues with the boiler, he also checked everywhere for leaks and he couldn't find any either. Eventually my neighbour got a specialist leak detection company in. He tracked all the downstairs pipe work with a thermal detector, a sound detector and also another method I can't remember. He spent some considerable time there but couldn't find any signs of a leak.

Can anybody else think of something he could check?

Are you sure the pressure relief valve on the boiler is operating correctly.If it is failing when the boiler is running it could be dumping water through the overflo...I have had this happen !..Find where the overflo exits the house and sus it out.

 

[SJB060685]

Expansion vessel lost its charge?

 

[townfanjon]

Logic boiler ? .

 

[PETE 123]

Heat exchanger leaking and water going down condense poss.

 

[MickBrown]

Expansion vessel lost its charge?

No it's fine, thanks.
[automerge]1604781393[/automerge]

Logic boiler ? .

No it's a Baxi.
[automerge]1604781438[/automerge]

Heat exchanger leaking and water going down condense poss.

The guy who fitted the boiler said a possibility and he checked for that.

 

[Chuck]

Can anybody else think of something he could check?

Leaking HX coil in DHW cylinder?

 

[SJB060685]

No it's fine, thanks.

The loss of pressure can only be down to a few things.
. Expansion vessel lost its charge, too little charge or too small all together. Putting a balloon over PRV discharge outside will rule the above or a faulty PRV out.
. Leak somewhere, although I'm confident from your initial post this is not the case.
. As mention above a split in the heat exchanger would show through condensate dripping when burner is not running.
[automerge]1604785317[/automerge]

Leaking HX coil in DHW cylinder?

If unvented system pressure would rise to mains pressure after PRV on cold to cylinder. If open vented then would equalise to head of header tank, not be on zero.