My daughter has a Potterton EP2002 system with a Potterton Suprima 40L boiler and a MPE322 diverter valve.
The system seems to be working OK for hot water but has developed a fault with the CH.
The CH will not come on unless the HW is on and the radiators will only heat up for as long as it takes for the water tank to reach temperature. When the tank stat says enough, the system stops heating, no matter that the room stat is still calling for heat.
I have remove the diverter actuator and checked that it moves according to demand. The valve is free to turn by hand.
The boiler fires when hot water is required (green light on) but will not fire for CH only (red light on). We did get it to fire for CH only by returning both controller sliders to 'off', switching the system off, then switching it on and sliding the CH control to 'on'. The boiler fired for a few seconds then shut off again.
Can anyone point me in the right direction to get this fixed?
Thanks.

David Taylor, January 2010

Thanks guys. I am off to Screwfix to get a new motor and try that.
http://www.screwfix.com/prods/28670/Plumbing/Central-Heating-Controls/Drayton-Synchronous-Motor#

Dave

David Taylor, January 2010

it may also be possible that the room thermostat may also require replacement check with a testing screwdriver that when your heating is on on the programmer you have live at point 1 and 3 and that 3 loses current when thermostat is turned down

0845 496 2402

J.B. Technical Construction, January 2010

The EP2000 series connections are
1 H/W Off
2 C/H Off
3 H/W On
4 C/H On

It may be lelpful for troubleshooting and diagnosis to deselect H/W on the programmer and just call for C/H.

Being an unqualified muppet I do not understand the wiring and switch arrangement in divertor valve heads but have been told on here that under some circumstances the signal asking the boiler to turn on is supplied from the divertor - there may be a fault with divertor head.

http://www.diyfaq.org.uk/plumbing/controls/midpositionvalve.htm

The boiler is obviously good - it has just lost a "please turn on" signal somewhere.

Good luck...

Peccavi, January 2010

replace the actuator, just because you can move it manually does not mean it is making the microswitch to activate the heating.

Ian, January 2010