No CH from Glow-worm combi

[GrahamT]

Hi

I have just re-sited a radiator for a client and had to drain down and then refill a Glow-worm swift flow 100 combi. When finished I tested and found that the DHW was fine but the CH is not firing-up. The Temp control is on full, all but the towel rail are TRVs on full, and the Towel rail is open full. There is no room stat, and the clock is on constant.

Anyone have any ideas as to why the CH is not coming on???

Any help, much appreciated,

Graham

 

[Agile]

Its not often that I am unable to think of one possible reason for a fault !

But in this case if the boiler is completely silent when you select CH then a stuck diverter valve is the only thing that I can suggest but I do have to say its unlikely.

Obviously air in the system is the obvious expectation but we know that it works on DHW so that seems to be less likely to be the problem IF the boiler is silent on CH.

Tony

 

[gasgeezer]

is the central heating switch on the boiler on located above the gas valve .Do not think boiler has divertor valve has bi-thermic h/exch relies on pump for c/h.

 

[GrahamT]

Yes, CH switch is on

 

[gasgeezer]

open pump vent see if it is spinning if not try to free it other possibility c/h thermistor fault check aav is open could be air lock

 

[Agile]

The boiler may well have a flow sw instead of a diverter read DHW flow SW but in that case the boiler would make a little noise when there was no DHW demand.

An open circuit sensor on the dhw will certainly stop this model from firing.

I encountered one last week but the sensor was OK however the sensor pin connections on the PCB were faulty.

An o/c CH sensor will probably also stop it from firing.

Tony