Connecting a CM927 thermostat to a WB Oil Heatslave

[jggoode10]

Hi,

I currently have a Worcester Oil Heatslave 15/19 with the fascia mounted Worcester programmer. I would like to connect a Honeywell CM927 programmable thermostat but since it only controls CH I need to continue to use the fascia mounted controller for HW. Is there a simple way to do this and still connect the CM927 unit?

Many thanks

Jon

 

[D_Hailsham]

Why do you need time control for a combi? It's an instant hot water heater, so will only come on when someone turns on hot tap!

 

[StuC]

Why do you need time control for a combi?

To control the times at which the heatbank is kept up to temperature?

Jon; have a look at http://www.worcester-bosch.co.uk/ca...atslave-combi--models-discontinued-dec-07.pdf

Page 22, fig 20 - remove the link, connect the stat and run the facia-mounted programmer in the always on position for CH.

 

[jggoode10]

Hi,

Correct - the Heatslave has a heatbank, the heating of which needs to be controlled for hot water.

Thanks for the info on where to connect the CM927. Can you confirm that that I wire the Relay box as shown in diagram 4a of the installation manual (Burner (direct control))?

Thanks

 

[StuC]

...ish.

You're referring to http://www.honeywelluk.com/Documents/Full-Install/pdf/1069.pdf I guess.

The boiler should get a permanent L,N & E from the FCU (so that the DHW can run whenever it's set to) and a switched live from terminal B on the relay box to fire the CH.

The relay box gets its permanent L&N from the FCU too, giving you a single point of isolation.


(Caveat: I'm not a sparky)