Central heating won't turn off

[Andrew79]

Hi,

Please forgive any inaccuracies in this description. I recently managed to blow up my programmer, the previous owner of my house had left wires exposed behind the wall plate, I presume they touched and shorted the system. I then stupidly managed to put a 13 amp fuse into the isolating box by accident, thus the programmer blew up.
The previous programmer was a Drayton LP722, so I have bought an exact match, put it on, everything seemed to be working peachy until the time I had set for the central heating to turn off came and went and the boiler continued to fire, and pump continued to run, although there was no call for either C/H or HW.
I have a Drayton LP722 programmer, Potterton Flamingo 50s boiler, Drayton Digistat, Danfoss ATC and Danfoss HSA3 motorised port valve. Does anyone have any ideas as this is driving me mental!
Cheers,
Andrew

 

[seco services]

check to see if the room stat or cylinder stat are still receiving power when hw/heating are off at the programmer.
does turning either the cylinder stat or room stat down to min stop it firing up ?

 

[Andrew79]

Hi Seco, thanks for the speedy reply,

When I turn the roomstat down to min, I can hear the motorised valve turn but the boiler stays on. When I down the cyl. stat down to min. the boiler stops firing up.

I thought that maybe it was the motorised valve, so linked the Heating Live and the Switched Live in an effort to bypass the motorised valve. Went down to the programmer and turned off the heating but the boiler continued to fire. I'm thinking maybe I've got a faulty programmer?