Central Heating Not Working But Getting Hot Water ??

[stevekawasaki]

Hi Guys or Gals..Please HELP as it's getting COLDER. The other day heating just stopped, thought boiler had packed in, but no she still fires up for Hot water. Iv'e checked the Pump and seems to turn no problem after undoing the large face screw and turning screw inside. Room thermostat clicks as normal( this morning after night shift at 6 degrees Cold) What im doing now is jamming the motorised valve by the pump in place (below manual) and the heating is comming on..? Is it the Thermostat, Motorised Valve or boiler controller....Boiler Myson Apollo with old clockwork timer, Pump Grundfos UPS 15-60 .. Thanxs Steve.......................

 

[Rob]

motor in the motorised valve it sounds like. about £10 and two wires!

 

[stevekawasaki]

Cheers Rob. If that works would have saved me VAST amounts in callout charge.It's a Honeywell 904, Do i buy the whole unit or just the motor and the two wires? and fit inside the original? Thanx again Rob

 

[MANDATE]

You could do with removing the head and look at the underside to see if if the motor is moving the quadrant form 'HW only' to 'HW/CH' and then further to 'CH only'.
You may find as I did when I had similar problem that the motor was in fact not the problem. When quadrant moves to 'CH only' position it triggers a microswitch to power up the boiler but in my case the microswitch was faulty.
A new head is more costly but will cure any motor or micro switch fault.
With the head off you can also test spindle for stiffness.