Help Please - Swapping Room Thermostats

[moddkar]

Hi,

I am trying to swap what I think is a faulty Drayton RTS1 room thermostat with a Drayton Digistat1.

The RTS1 uses 3 wires N, L and Call-for Heat.

The Digistat uses 2 wires Common and Call for heat. ( a 3rd can be used "Heating Satisfied" but I don't need that, I don't think)

Which is common?

The RTS1 says 230V 3A fused near the N and L wires, but the Digistat says volt free contacts (and has batteries installed). So do I use N or L or neither.

I'm stuck...............

Any help appreciaetd.

 

[croydoncorgi]

I think we need a room thermostat FAQ!!!

A '3-wire' thermostat is 95% of the time a MAINS-voltage gadget and, if so, MUST have a NEUTRAL connection. (This is NOTHING to do with a 'SATISIFED' connection which may in rare situations ALSO be needed, thus totalling to FOUR wires plus Earth.) The Live terminal normally connects to the programmer, the Call terminal to the motorised valve (if any) or directly to the boiler + pump.

Electronic, digital and radio stats are MOSTLY 2-wire. If the actual box on the wall has batteries, DEFINITELY 2-wire. There should be terminals marked Common, Call for Heat and (maybe) Satisfied. Live from the Programmer goes onto Common, Call for Heat is connected to the motorised valve, etc.

IMPORTANT NOTES Many combis and some system boilers with integral diverters have LOW VOLTAGE control systems. You MUST NOT under any circumstances connect mains to such controls in any way. If you use a wire colour-coded OTHER than Brown (or Red in old money) to carry Switched Live you MUST put a red sleeve on it at each end to indicate that it's Live.