I’m visiting my Dad, who has a much higher water bill (metered), seemingly caused by water flowing out down the overflow pipe from the heat pump. You can see the water through the tun dish. It’s constant apparently and the water is sometimes warm. Pressure looks normal. I suspect it’s a problem with the pressure release valve?
Am I correct in thinking water shouldn’t flow there normally and that it only happens if the release valve is ‘tripped’ or faulty.
I’m not being a tight arse, it’s just that the guy that installed has emigrated and other plumbers won’t come and have a look, as they don’t normally work on these systems.

A tundish is there so you can see if it’s leaking. It’s not meant to have anything running through it so yes I would say you are right.

Can’t help on the installer front unfortunately.

Another look shows that one of the pressure release valves on the water supply appears faulty – hisses when you try to top up the pressure to the boiler, and has limescale on it, which ties in with the months of the rising water bill I guess.

Just so you know, if it’s an unvented cylinder, you need to have a G3 ticket to work on these. May explain why you can’t find a plumber to work on it. Where in the country are you

Near Carlisle

Hope this helps

If it’s constantly loosing water through the TPRV and not loosing pressure, there is a problem with the filling link. Either it’s not closed or it’s allowing bypass.
The system sounds tom me like it’s at mains pressure constantly and therefore will continue to fill and maintain the limit on the TPRV. Hence the water bill.
That’s my best guess without a visit of course.

Thanks Gents, chased a plumber up today – thinks it’s a pressure valve on the unit itself.

Double post

If your near Carlisle, try greenfields at penrith, i can vouch that these are good guys. I think they work on heat pumps.