Swapping T40 for a Horstmann DRT2

[abzthemanc]

Hi all,

Need some help swapping out a current T40 Thermostat for a Horstmann DRT2

Got two images below, one of the current wiring into the T40, and the other of the diagram from the DRT2.

I HAVE had a look at previous threads on here and other sites, and am getting confused as I can't seems to apply exiting answers to my wiring, without being 100% sure.

From the image below, it looks like I have 3 core wiring? Is there a safe way to test this?

How should I swap out the wires into the new thermostat? I assume I should use blocks to close off the unused wires such as the earth wire? (No earth connection on new stat, and manual shows it as double insulated..)


Thanks all in advance

 

[hertsboilers]

Old "1" to new "com", and old "3" to new "NO".

 

[abzthemanc]

Old "1" to new "com", and old "3" to new "NO".

Thanks for this. For my understanding, what is the purpose of each of those wires? ie Are they both 'live'?

Thank again

 

[hertsboilers]

Old "1" to new "com", and old "3" to new "NO".

Thanks for this. For my understanding, what is the purpose of each of those wires? ie Are they both 'live'?

Thank again

The thermostat is a switch.