In this phase you can see which type of boiler you have, and which thermostats work with underfloor heating. Depending on your situation, you can choose from a certain number of smart thermostats. If you make the wrong choice, then it may be that your thermostat does not work properly.
1. Which thermostat works with my central heating boiler?
The first and perhaps the most important question that you have to ask yourself when choosing a smart thermostat. If you choose the wrong one, your thermostat will not work as it should.
There are two types of central heating boiler: On / Off and OpenTherm (also called modulating). An On / Off boiler will turn on if a room is too cold and goes off when the desired temperature has been reached. The disadvantage is that the boiler maximally heats and therefore also 're-heats' when the room is at temperature. This means a room can still be warmer than the desired temperature.
An OpenTherm (modulating) central heating boiler adjusts the flame to the heat demand. If, for example, the temperature only needs to rise a little, the heating is not fully switched on. The boiler keeps the water temperature at a stable level, making it also more energy-efficient than an On / Off boiler that continuously switches on and off.
Which thermostat should you choose?
Some thermostats work with both types of boilers, such as the Nest thermostat, Tado V3+ thermostat and the Honeywell Lyric. Other models come in two versions, such as the Honeywell Evohome OpenTherm and Honeywell Evohome On/Off. Still others only support one type of boiler, so pay close attention to which smart thermostat you choose.