hello, I’m looking for some expert advice. A recently completed extension has wet unfloor heating installed. The stat is hard wired to the boiler with a probe into the floor. The stat is a SolFex slimline. The rest of the house also has wet underfloor and is on a Heatmiser RF system. The issue I am having in the extension is that the stat has trouble reading over 19 degrees C in the morning after a cold night. Yet the room and floor are really warm. Using an infrared thermometer gun this morning the floor temp was at 29 degrees (wooden floor so likely too high), the walls internally were in the 23-24 range and the room felt hot. Using the IR gun very close to the stat and on the air intake of the stat the temp dropped considerable. Temp in that area was in the 20 degree range and at the air intake sometimes 19 degrees. This suggests to me that as the stat is in a back box, there is less insulation around/behind it and therefore the stat is reading a lower air temp based on the outside temperature, causing the room to over heat. Obviously I don’t want to over pay for heating but also, the room is getting much hotter than it needs to be and on the verge of uncomfortable. The extension is wood frame with outside boarding, 100mm insulation, then another 25mm before the plaster board. The stat is in a normal sized back box. Any suggestions on a solution? Here are the potential options I thought of so far. - try to insulate the back box, to cut out the draught or some of the inside outside temp variance. Could I use insulating foam spray? The digital part of the stat fits to a plate via a connector, the plate fits to the metal back box. Loads of space in the back box other than the wires. - turn the stat down so that it cuts out at a lower temp and hope the room temp will be ok - replace the stat for a surface mounted or smart stat. Filling the back box with insulation. (Technically I may still be able to keep it wired?) Any advice is welcome. I am in the Guildford area if any great heating engineers are nearby and have ideas or want to help. The rest of the house on Heatmiser RF stats is working fine. These are battery surface mounted stats and therefore I assume not facing the same issue. The rest of the house is wood frame too. That sits at a constant 20 degrees really nicely, floor temp there is around 23-24 degrees in the morning. Thanks P.s. I have replaced the stat as I originally thought it was faulty but still has the same issue.