Can't run central heating pump without hot water running

[monkeyfinger]

Ideal Boiler
Danfoss FP715 timer
Heatmiser PRT room stat
Sunvic SD 2701 3-way valve
Danfoss AT tank stat

I run this system with central heating on constant, timings controlled by the Heatmiser thermostat. I switched the CH off a week ago (at the Danfoss timer). Put it back on yesterday at wife's insistance, and an old problem has returned where I cannot get the CH pump to run without having the HW on and the tank stat triggered. This results in very hot water since I have to keep turning it up. I know that I will turn the system off again soon, but would like to get this sorted before next winter. I am assuming a timer or motorised valve head fault. Any ideas or checks that I should make? - at one point yesterday, the Danfoss timer was going a bit mad with both HW and CH lights flashing and clicking on and off, so maybe the fault is the timer?

 

[gas4you]

The standard reply would be change the 3 way valve head, but as you indicate this programmer fault, I would check all wiring connections are tight, then reset the timer.

If this does not work, I would link out the live and heating terminals with the timer removed. If the ch works ok, replace the programmer.

 

[BingoBongo]

check the programmer is secure on the backplate

if so sounds like programmer is gubbed

 

[monkeyfinger]

Thanks for the response - I understand this as connecting the live feed to the HTG on terminal - is that what you mean? If I do that, what should happen?

 

[seco services]

the heating should come on.