While the Passiv Smart Thermostat is fully compatible with underfloor heating systems, it supports a maximum of two heating zones. If the underfloor heating system is currently split into a heating zone for each individual room, these zones will have to be combined or completely disabled to create a single open zone. This would, for example, result in a single zone for downstairs and a single zone for upstairs, which would then allow the Passiv Smart Thermostat to control the provision of heating for both of these zones.
Including other systems that control different heating zones can limit the Passiv Smart Thermostat's ability to provide sufficient heat from the heat pump.