If you have underfloor heating, and you want to include this in your multi zone system, this is possible. This works differently for Tado and Evohome.
If you have underfloor heating in your home, you have an underfloor heating distributor. The boiler supplies warm water to the distributor via your heating pipes. Pipes with warm water enter the floor from this distributor. These pipes run in a loop and thus return to the distributor. The water flows back to the boiler through your heating pipes.
With Tado you can only control an underfloor heating manifold as one zone. You do this by placing a zone valve in the supply pipe to the distributor. This valve opens or closes the pipe, which then does or does not heat the underfloor heating.
The zone valve is controlled by the Tado thermostat. For this, the thermostat must be wired to the zone valve. Please note, usually the wire from your thermostat goes to your boiler. This means you will have to install a new wire that will run to the underfloor heating distributor!
Because the Tado thermostat can only be wired to one part, it must communicate wirelessly with the boiler. This can be done by means of the Extension Kit.
With Evohome there are several options. Just like with Tado, you can choose to control it via a zone valve. With Evohome, the zone valve is controlled via a wireless on/off relay.
You can also choose to divide your underfloor heating distributor into zones. This is especially convenient if e.g. you have underfloor heating in the living room and (closed) kitchen, and you want to operate it separately. You then need an extra Honeywell HCE80 distributor and servo motors. These servo motors are placed on the connection of the pipes of the underfloor heating. Because each tube can be opened and closed in this way, you can control them separately.
Please note, you therefore need a thermostat in every zone with underfloor heating. Otherwise, the system does not know how hot it is in the zone and therefore does not know whether / when to start or stop heating.
Because the system can become very technical in combination with underfloor heating, we recommend that you have this installed by a professional.