Adding a Honeywell CM927 to an ancient system...

[deanbayley]

Hi guys,

We have just moved into our new house, the heating system is a Potterton Prima 30B controlled by a Potterton EP2002..

In our old house we had a combi boiler with a Honeywell CM927 wireless stat, I brought it with us because it always has the house at the perfect temp at the right time..

I had a look at the EP2002 wiring and thought it was best left alone so attached the control unit in place of the old dial stat..

I'm assuming from following the wiring that the stat controls the diverter valve (there is a yellow wire on the old stat and the only yellow wire anywhere else is going to the diverter valve)..

I'm also assuming that the white wire on the diverter valve is switched neutral..

I'm also assuming that the way system works is the boiler keeps heating water until it reaches the set temp, the boiler tells the EP2002 when it has reached temp so it can stop the pump and the stat controls the diverter valve to expand the system to the radiators as well, or does the pump run constantly?

Can't wait till jan when we install a Worchester Greenstar CDI 30 in the loft..

If someone could confirm or dispell my assumptions I'd appreciate it..

Regards,
Dean.

 

[Dan Robinson]

Possibly.
No.
No. Boiler doesn't say 'owt... Diverter valve keeps boiler and pump on...

 

[ChrisR]

The wires in your box could be any colour - we can't tell from here.
Just connect L and N to the receiver of the stat, and use the volt free connections to replace the thermostat common and Normally Closed contacts.
It's Worcester not Worchester
Your Prima will probably outlast a Worcester CDi. We just scrapped two which were driving their owner nuts. About 7 breakdowns in under 3 years, between them.

 

[deanbayley]

I'm open to suggestions, my parents have both had Bosch boilers without issue for a long time, which combi would u recommend?

Dean.

 

[deanbayley]

As mentioned here: //www.diynot.com/forums/viewtopic.php?t=284405

From the diagram (same stat) it looks like it switches the neutral??

Dean..