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We have a basic thermostat controlling our under floor heating. It's quite crude it how switches on and off.
It runs on 24v AC.
I am trying to make sense of what I am looking at, as I would like to swop it out for something a little more accurate.
There is a basic wiring diagram inside the cover as below and what I actually have connected below that.
I am getting 24v AC across 4 and 2. There is nothing connected to the far left terminal (also labelled 4).
I am assuming that the A/B terminal is what makes the call to the valve?
But why is there a connection to terminal 1?
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Despite trying to interpret that label, I have no idea, sorry.
But 24v AC? I’ve never come across that. Most stats I know are on 240v ac. Just be careful, isolate the mains please!
It's definitely 24v AC, there's a transformer above the manifold.
Glad you’re still alive.
I think terminal A/B should be connected to the output of a timer.
Note there are two terminal 4’s, and you can see they’re connected on the PCB. They are both 0V.
24v supply to terminal 1. Leaving the load (the valve right?) to be connected between 1 and 4 (0V).
The installer just hasn’t bothered to bring the 0V on the valve up to this stat, it must be connected to 0V elsewhere, leaving that terminal spare.
So 1 is the “call for heat”
All guesses on my part.
@Goldfish24 Many thanks that makes more sense now.
Your guesses are right.
There is a timer in the system.
When the led is lit then I get 24v across 4 and 1.