Connecting a Honeywell DT92E to a Worcester 24i RSF

[bingobanjo]

Hi there all,

My central heating system has no room thermostat attached and I am planning to connect a Honeywell DT92E to a Worcester 24i RSF Combi boiler.

At present the boiler has an old-looking mechanical clock attached.

Not wanting to cause any damage to my system I am looking for a sanity check on how to wire this up. Should be dead easy I know, but I do seem to have a track record of knackering things up when it comes to household electrics!

The diagrams below show the two options I can think of:

Method 1

• bingobanjo
• 22 Apr 2012
• 1

OR

Method 2

• bingobanjo
• 22 Apr 2012
• 1

The BDR91 is the honeywell wireless receiver relay unit and I've shown the clock timer and boiler connections as well.

Am I right in thinking the second option (image on right) is the correct one? I assume that if I use the first option, the wireless receiver unit will only have power if the clock is demanding the boiler to fire up (which I assume is bad).

Using the second option the receiver will have permanent power and will always operate the internal relay but boiler will only fire if timer is also set or manually overridden create an AND effect. Hopefully my logic is correct here. I found the manual for the DT92E a tad confusing and have had no experience fitting such a device. Just don't want to foul things up.

Cheers all

 

[kdoheating2011]

you can do it any of them ways as the timer needs to call for heat on both circuits for the boiler to fire

 

[mikely]

Or get rid of the old timer and fit a programmable Honeywell CM927 instead?