Hot water but no central heating

[mpn]

Just had a radiator moved, system was refilled & switched on, hot water is fine but no central heating, worked fine before. Boiler is Glow worm 100e combi. Room thermostat is working as is control clock.

 

[Bahco]

Is the pump working and system pressure correct?

 

[Slugbabydotcom]

After checking the above

Behind the pump is an automatic air vent with what looks like a tyre valve cap on it. Make sure this is loose by about one turn.

If that is the cause of the problem you will probably hear air coming out when you loosen the cap.

This cap is meant to be left loose and not re-tightened

 

[mpn]

Air vent cap is loose, pressure is ok how do i test pump?

 

[kevplumb]

undo the screw marked bleed and see if the shaft is turning

 

[Slugbabydotcom]

You can usually hear it spinning when theres a call for heat. I often use a large screwdriver as a listening stick. Others prefer to remove the cap on the face of the pump but expect a bit of water if you do this. Put an old towel in the area. No guarantees either way there tho ... That just gives you an idea because sometimes the shaft can spin but the impeller has snapped off.
Feeling the flow pipe getting hot can sometimes be a better indication of the pump doing its work properly.

Answering the following will help us to suss out more about whats happening:-

Did you bleed all the rads?
Have all the valves been opened in the circuit?
Is the boiler firing for C/H at all?
Are any radiators or pipes other than the hot you already mentioned getting warm?

 

[mpn]

Rads bled and valves are open, boiler make a noise when you switch heating on for about 10 seconds then switched off. Undid screw on pump, water sprayed out when central heating was switched on until boiler switched itself off, not sure if that means pump is ok but it was very quiet if it was running. Red light then came on for low water pressure, topped up pressure but light stays on and no hot water now!

 

[Slugbabydotcom]

Undid screw on pump, water sprayed out when central heating was switched on until boiler switched itself off!

SO after you undid the screw on the pump and while the water was peeing out did you get a screwdriver in to see if the shaft was turning?
Sounds like it may have locked out - try the reset button.
If the red light you are on about is definitely the low water pressure light then either the boiler doesnt have enough pressure or the low pressure water switch is faulty. What pressure is indicated on the guage?

 

[mpn]

Bypassed clock and roomstat and returned boiler to factory settings and using central heating control on boiler, hot water and central heating are fine, just waiting for electrician to see if problem is with roomstat or clock, my moneys on the roomstat. Thanks for advise so far.