Heating only comes on with hot water - why?

[slipshot]

Chaps

At the risk of sounding like an exam question, two days ago our system worked fine with the heating and hot water coming on in the morning and evening. Then, when we boosted the heating during the day, the boiler did not fire up. Checked the thermostat and increased that to ensure the boiler would do (as we have done hundreds of time in the past) and nothing happened. But then, when boosting the hot water, the boiler fires up, and the heating kicks in (as in after 10 mins the rads start to get warm).

So for some reason, the boost button or the unit is not sending the call for heat - but when the boiler is fired through the hot water request, the heating seems to work fine.

Thus we have heat and hot water, but the heating is only working when the hot water is activated. Any ideas? I assume it's something in the programmer (Drayton Tempus 7) since this provides the control, but anyone any other ideas?

Thanks

Andy

 

[Agile]

It sounds as if your motorised valve has failed!

Tony

 

[slipshot]

Thanks Tony - presumably the box would trigger and the motorised valve would activate - but would the hot water coming on also activate the motorised valve, as I think (or did think) that they would be different - or have I got that wrong.

Andy

 

[weareleeds]

May be end switch failed on 3 port valve so when calling for both it drives to mid position but when cyl stat satisfied won't make switch. For time being just turn cyl stat to max & blr stat lower

 

[slipshot]

May be end switch failed on 3 port valve so when calling for both it drives to mid position but when cyl stat satisfied won't make switch. For time being just turn cyl stat to max & blr stat lower

Thanks - will check tonight but I think it is two twin port valves rather than 1 three port - will have a look and see if I can make sense of anything...

 

[gas4you]

Replace the head on the ch valve.

 

[slipshot]

Replace the head on the ch valve.

Thanks - assume you mean the white box which is a Drayton motorised valve? As in these things:

http://www.invensyscontrolseurope.c.../en/ProductsServices/Drayton/MOTORISEDVALVES/

Andy