Replace mechanical Thermostat with Digital REV100

[wrightyintheafternoon]

Hi

I currently have a mechanical Honeywell T4160 Thermostat and would like to replace the unit with a digital thermostat a REV100.

The current unit is wired as:-

2 - Single Black (Separate cable)
3 - one of a pair of red
1 - second of the pair of red

Earth not used. I believe this circuit switches the motorised valve in an S plan system. The motorised valve in turn switch the pump and boiler.

If I check the circuit with a meter I get the following

Stat below temp

1 & 3 = 240V
1 & 2 = 0V

Stat above temp (I.e turn heating on)

1 & 3 = 0V
1 & 2 = 240V

2 & 3 always read 240V

Now on my new Digital Siemens REV100, I only have two connectors, L and L1 (T1 & T2 for remote sensor only I think).

Does anyone know how to swap over the connections.

I tried Single Black to 2nd of red pair, but this popped the circuit breaker.

Thanks in advance.

 

[breezer]

both reds and put black in choc bloc

 

[wrightyintheafternoon]

Hi Breezer

Thanks for you very prompt reply.

I have just swapped the unit over and all seems well.