Electrical Heat Switch for UFH without Room Thermostat?

[cpc6128]

It looks like a straight swap from my existing (non-smart) electric UFH thermostat to the Wiser Electrical Heat Switch. I already have a floor sensor that I can connect. Is this sufficient or is it mandatory to also have a Room Thermostat connected? (this is for the bathroom where the rad is a bypass so doesn't have a TRV or smart valve)

In our kitchen I also already have a rad with a Wiser Radiator Thermostat. I assume this means I don't need to a separate Room Thermostat to use with UFH? Is it possible to control the rads and UFH separately i.e. have the rads off but UFH on (just to take the chill off the floor?)

[Garyct]

I have a similar configuration and I think you will have to have a separate room thermostat for UFH. I tried to add the Electrical Heat Switch to the same room (kitchen) which had a rad but I couldn't get it to be accepted. As I understand it the floor sensor is only to prevent the floor heating overheating in the event the room thermostat fails.

I actually ended up with a room thermostat for the rad in the room called Kitchen (due to its location in a corner next to some units, it was in a local hotspot so it was turning off before the room was warm) and a separate room  thermostat in the same physical room but called Extension for the WEHS. It is one big room (an extended kitchen/dining room). The two thermostats sit side by side, but I program the extension thermostat to be 2C below the kitchen thermostat. This way, the room will preferentially use the radiator to heat the room. Only if the room temp drops 2 degrees lower than the kitchen thermostat setting does the EFH kick in. I did this because the EFH cost a fortune last winter.

I can also boost the Extension room separately thus providing under floor heating independently from the radiator.

Not the cheapest solution but the most flexible.  

[cpc6128]

interesting. Still debating what do to, I might remove the WEHS and just connect the underfloor heating to a Shelly relay or similar. The problem is, I don't really want to use the UFH to heat the room, just to take the edge off the cold tile floor! Maybe I will try setting the WEHS room thermostat quite low and see if that works.

[Garyct · Accepted solution]

I believe you will have to have a separate room thermostat for the Heat Switch. The floor sensor is just a backstop safety cutoff sensor.  I had a room with an existing radiator and thermostat and couldn’t add the Heat Switch to that room. I had to have an additional room thermostat just for the UFH on the Heat Switch. Same room, 2 thermostats sit side by side. Sounds crazy but is more flexible as I can set the schedules/temps such that the bulk of the heating is done by the radiator, with boosts as required by the UFH.