Replacing old 3-wire room thermostat

[steviewevie]

Hi there, I have a very old 3-wire mechanical room thermostat. I'd ideally like to replace this with an electronic one, but all the ones that I can see are for 2-wire installation. It's just the thermostat I need, this is in the lounge, I already have the timer controls by the boiler in the kitchen.

Do I specifically need a 3-wire thermostat ? I looked at a Honeywell 2-wire one that had various wiring diagrams including one with three wires going into it, but it didn't have an explanative text so I couldn't figure it out.

I have found 3-wire rotary ones, but not an 3-wire electronic ones with a display, though perhaps I am missing/misunderstanding something.

Thanks in advance for any help !

 

[mysteryman]

Don't make the neutral connection. It's there on an electro-mechanical room thermostat just to power the anticipator heater, giving closer control.

You just need live in, and switched live out.

 

[steviewevie]

So I will be alright with a 2-wire electronic one then ? Great, thanks !

 

[flameport]

So I will be alright with a 2-wire electronic one then ? Great, thanks !

Yes, provided you want to put batteries in it every year even though there is mains power available from your wiring.

Alternatively buy a mains powered electronic thermostat.