Potterton Suprima-Water OK-Central Heating?

[shudson]

I am not a Heating Engineer - so please forgive terminology!

OK - seen lots of posts about PCB's etc, but none mention my specific problem.
Water heating is fine, no complaints at all.
Central heating is the problem. If it is turned on (with water heating turned off), relays click in etc and burner sounds like it lights, then after 5-10 secs it goes quiet, and nothing happens. Room stat is set to high. BUT - if the water heating is on, or the water heating is turned on while CH is on, the radiators heat up fine without any problem at all.

Would appreciate any input (apart from skipping the boiler).

 

[gas4you]

Sounds more like a stuck 3 port or 2 port valve.

Boiler is dumb and dosen't differentiate bewteen heating of hot water. The boiler just gets a call for heating something.

The zone valves are what tell the water where to go.

If you have 2 x 2 port check the ch one, if a 3 port change the head.

 

[corgiman]

what valve(S) do you have are there any id's on them?

 

[shudson]

OK, in October an "Engineer" changed the valve. This did not resolve the problem. After 15minutes of head-scratching he asked if this was a new fault. I told him I had only lived here a few weeks and was unsure. He had to go by this time, but suggested that the problem was probably that the whole thing had been wired incorrectly from day one. Property only built 3 years ago. I tried to contact the "engineer" but during my last conversation with him, he declared that electrics were not really his thing! (Yes he is corgi registered.)

Any ideas?

 

[MANDATE]

Like the guys have already indicated, motorised valve seems favorite.
You will find quite a few on here have had similar problems.
Usually caused by (a) stiff valve spindle (b) failed synchron motor due to (a). (c) failed micro switch (dirty/burnt contacts) and (d) incorrect wiring.
Have a look at similar problems over the last 3 months.
If you have a new valve, it would not surprise me if the wiring is at fault (ie a wire missing)