Heatmiser PRT-E-V3 7-Day Digital Thermostat Programmer Item Description: The PRT-E-V3 Underfloor heating thermostat has been designed specifically with electric under floor heating in mind, able to control up to 16amp load. Operating Modes 1. Floor sensor only. Ideal when you only want to control the floor surface temperature. (Conservatories for example) 2. Air and Floor. The thermostat controls the air temperature whilst using the floor sensor to prevent overheating of the floor system. 3. Remote Air and Floor.