Wiring Smart Thermostat from Old Battery Thermostat

[Jonathan Sherratt]

Need some advice as to how to wire up my new Smart Thermostat (picture 1 below)


My Old Thermostat has three wires red, blue and yellow( taped red for live) and runs on 3V (see picture 2)

The new Smart Thermostat needs 240V independent for 3 and 4 as it is a dry contact. Just need to know which wires go into 1 and 2. My understanding is that:
blue = neutral wire so not needed so
earth= not needed
red and yellow wires go into 1 and 2?
red in 1
yellow in 2???

 

[Taylortwocities]

Your answer is on the Screwfix forum.

 

[ericmark]

Yes Com and ON become 1 and 2.

It should be neutral to 3 (N) and a link between 4 (L) and the permanent line but without testing we don't know if that is 1 or 2 so you will need to test. And the old thermostat would work without a neutral [3 (N)] so no guarantee you have a neutral.

I really can't see the point of changing, I made the same mistake, I fitted Nest Gen 3 under the impression it would link to my TRV heads, but found out it did link but it did not accept demands for heat from the TRV heads so it was rather useless.

It may work if you carefully set the TRV heads, the idea is the TRV head sets the room temperature to below the point when the wall thermostat will turn off, so when we get a warm day, the boiler will then shut off and it stops the boiler cycling. The TRV heads connect to phone, so we get a report showing how it has done, and we can set when each room is heated, in my case only 4 of the 9 electronic TRV heads are wifi connected, the other 5 bluetooth only. Times are set on the TRV all the wall thermostat does is turn off boiler on a warm day.

I did try geofencing, and to be frank it did not really work for me, all that happened was in the storms the EE mast went down and caused my heating to switch off, so it was disabled.

 

[Deleted member 267285]

Need some advice as to how to wire up my new Smart Thermostat (picture 1 below)


My Old Thermostat has three wires red, blue and yellow( taped red for live) and runs on 3V (see picture 2)

The new Smart Thermostat needs 240V independent for 3 and 4 as it is a dry contact. Just need to know which wires go into 1 and 2. My understanding is that:
blue = neutral wire so not needed so
earth= not needed
red and yellow wires go into 1 and 2?
red in 1
yellow in 2???

If you think it runs on 3v think again.