Home Technical Questions

Replacing v1 thermostat with an v3 extension box

Hi, I wonder if anyone would know how to replicate the wiring on my v1 thermostat on a v3 extension box. I'm a bit confused as I only seem to have 3 wires!

This was done a few years back by an installer.

This is the back of the extension box.

Thanks for your help in advance.

Sign In or Register to comment.