Hot water problem driving me loopy...

There could be lots of reasons. Wiring issues, thermostat failure, boiler problems, unreliable convection, unreasonably high expectations of performance (convection circulated primary circuits are only intended to heat enough hot water for a hamster to have a 10 second shower once a week).

There is simply not enough information here to determine which.

Christian.

Is the actual burner lighting up?

Jesus! that must have cost you? "it took a good few hours for the water to get hot. He said its normal, and its more"

-- Sir Benjamin Middlethwaite

What sort of cylinder is it?

sponix

No, he's the landlord. It's costing the tenants.

He has a disincentive (?) on spending money on upgrading the antediluvian, inefficient heating system or on a competent heating technician.

I suspect that there's air in the gravity circuit - stopping it from circulating properly. The first thing to check is that there's some water in the fill & expansion tank. Chances are that the ball-valve has stuck closed and the water has all evaporated - allowing air to be drawn in. The gravity circuit would likely give up before the pumped heating circuit under these circumstances.

I had another chat with the tenants, it seems that the pilot light is going out - even though it initially heats the water. Reading the posts on this group seem to point to a problem with the thermocouple (or possibly a draft - though i doubt this). Will get the plumber to take a look.

And yes... in my first post i did say they 'apparently' checked the pilot light - see what i mean about unreliable information from students?. Can you believe they even thought there was a ghost in the house in the initial days!!!!! I told them i cant find a ghost catcher and they should stop imaging things.

You should have told them you were adding the ghost to the inventory and if they couldn't show it to you when leaving the flat you'd dock their deposit.

Owain