Ask a plumber/heating ‘engineer’ anything

Saw the electrician one and I’m abit bored today so go ahead, other plumbers join in

How often ? And what boiler is it?
It could be a faulty/undersized expansion vessel causing the pressure to rise and the pressure relief valve opening.
The boiler heat exchanger leaking and the water running down the condense.
A small leak which evaporates away and you not seeing it, look for staining one pipes/joints too.
Radiator valves are most common for leaks causing pressure loss, check trv valve bodies after taking the head off, Drayton trv4 valves leak a lot !
. Water doesn’t compress much, so depending on the size on the system to go from 0.1 bar to 1 bar doesn’t actually take much extra water.

We have a non vented hot water system and gas fired central heating.
Recently despite both water and heating being set to Off in Nest the boiler fires up and the radiators get hot for a short period?
The times seem to be random.
Why would it be doing that?

Oh and to continue with the non serious theme of these threads:

Have you ever serviced any randy/lonely housewives?

Do you know the secret masonic handshake and if so can you tell us what it is?

Why is it that people think Plumbers get payed a lot?

Have you opened the radiator valves?

Yes they were never closed. The system got drained completely when the rads were removed (by accident as the water pissed into the downstairs basement flat 😂)

Why do plumbers have 13 grannies, permanently sick children, and unreliable vans that get broken into and break down all at the same time, so they can't manage to make appointments.

Oh and why is the supplier always out of stock of that generic item, and the replacement can only be picked up from a different supplier 50 miles away in a week?

Google it ffs but basically it uses the latent heat of condensation at 50-55 degrees to reheat the water in the heat exchanger. That’s why there is a drain pipe (condense) to remove the excess water.
Pressure should be 1 bar cold.