Is your radiant celing heat 120 volts? Is there a neutral in the feed that supplies the radiant heat if it is 240 volts? Was the white wire connected? Does the old thermostat need 120 volts to work correctly or display correctly?
I will get you an answer with the answers to these questions. Thank you.
My radiant heat is 240 volts and the white wire is connected to the common screw
Does some part of the thermostat require this white wire to operate? Is the thermostat double pole? How many wires total are in the box with the thermostat? Is there 1 line and 1 load or 2 of each?
1 set of wires to box from breakers are black white and ground. the black wire goes directly to line on old thermostat the white is tied to one red going to heater. the other red wire from heater goes directly to load. I've got a new double pole thermostat. Do I tie the hot black with the 2 blacks on thermostat and tie the 2 reds on thermostat with single red in box and then cap off the white
I just arrived home. We can continue to get your solution here. There is no need to relist.
Now I understand your wiring. The white wire is not a common or neutral wire. The white and the black are the 240 volt lines. These 2 wires need to connect to the two line terminals. The black and red wires from the heater will connect to the 2 load terminals. This will properly disconnect the entire electrical circuit from the heater. Your documentation that came with the thermostat will tell you which is line and which is load so you don't make a mistake. The white wire, by code, is supposed to be identified with black at each termination when it is used as a power wire like this. This will assure nobody will mistake it as a neutral and get hurt by it.