I've had the programmer set to hot water only since it's been warm and
since yesterday morning, we've had no hot water. When I say no hot
water, it's very lukewarm.

So I thought I wonder if the motorised valve is faulty?? I set the
programmer to both heating & water and it had not made any difference.
The radiators is just luke warm too.

The pump is working ok (I only replaced this less than 2 years ago)
The motorised valve must be ok (Again I only replaced this less than 2
years ago).

The boiler does fire up and heats but only for 10 mins maximum before
it shuts down again.

I replaced the thermocouple was replaced approx. 6 months ago, when the
pilot light would not stay lit.

I then wondered if there is 'air' in the system or some leak? I've bled
all the radiators and thats was all ok. Checked the header tank and
plenty of water in there.

I am guessing that it could be either the boiler thermostat that is
faulty or could it be a more serious problem, like the heat exhanger??
It's a Thorn Apollo 30/50B - an older boiler that needs replacing but
it will have to wait until it's a must.

Anyway - any ideas what it could be before I call the heating engineer
out??

Look forward to your replies

blister72