Another Potterton Prt2 Thermostat Replacement Thread

[Thomas Kranenburg]

Afternoon and Merry Christmas all. I have read a lot of Potterton Prt2 thermostat replacement threads on here and they've been a great help. I just want to totally clarify a few things before I consider buying a replacement.

Here is the wiring of my existing Potterton thermostat:

Now Ideally I'd want to replace it with this:

https://www.amazon.co.uk/MCO-Home-Heating-Thermostat-MH3901-Z/dp/B08B8TVB1J

The wiring diagram for it is as follows:

Now I notice here that the Potterton takes a mains power supply of 240v. While the MCO thermostat takes 24v. Is it still possible to use this thermostat? Would I need a small transformer?

 

[trojanhawrs]

What is the model number of your boiler?

 

[Thomas Kranenburg]

It is a Baxi combi 80 max flu.

 

[Stuckinarut]

It is a Baxi combi 80 max flu.

Looks like you need a mains voltage compatible thermostat. The one you're looking at doesn't appear to support this.

 

[trojanhawrs]

You'd need something then yes, the other issue is you'd need 4 cores if you were to mount the transformer at the boiler side and you only have 3 (your old thermostat is sharing the live for power and heat signal).
So basically you'd have to fit a transformer/adapter where the thermostat is now and run a 4 core cable between that and the new stat. Or you could stick with a mains voltage stat/2 part stat like the hive/nest

 

[Thomas Kranenburg]

Yeah there's just not a lot of options if I go for mains voltage. I am looking for something z-wave compatible and not cloud based. If anyone has any suggestions I'm open to it. I just want it to look nice really. It's just a switch at the end of the day.

 

[Thomas Kranenburg]

Anyone have any suggestions for a transformer? I'll consider it.

 

[EFLImpudence]

You could buy a new boiler for the thermostat.

 

[Thomas Kranenburg]

Another option is this:

Heatit Z-TRM3 White RAL 9003

Z-Wave thermostat 3600W 16A 868,4 MHz

heatit.com

This should be ok shouldn't it? I think the pilot wire would be optional?

 

[trojanhawrs]

If you have space next to the boiler you could make up a box with what you need. 24v power supply and Relay. This would let you use the existing cabling between boiler and thermostat