I'm installing a nest thermostat in my house - it's the UK version with a heatlink. I have successfully wired the heat link into my combi-boiler, disconnecting two existing wires in the process.
I have a thermostat in a different room (Honeywell CM707) that I've removed from the wall. There were two wires connected to it.
This is the wiring diagram for the thermostat:
From this I am expecting that the two wires I disconnected from the boiler are the two that connected to the old thermostat.
However: I tried measuring the voltage across the two wires that were coming out of the wall - when the multimeter was in DC mode it registered zero, but in AC mode it registered 12V. Am I right in thinking this means they cannot be the wires that I disconnected from the boiler? IE if A and B in the diagram was where I was measuring the voltage, and T1 and T2 were completely disconnected from anything, I should not get a voltage across A and B, right?
To me this is a given but I was wondering if there was something I didn't understand about the way multimeters work when they were on AC settings!
EDIT: this is the wiring diagram from my boiler - the wires I removed were in the points labelled 1 & 2 (there was no link cable).