Radiant Heat Won't Shut Off
I purchased an older home about 3 years ago with radiant heat in the ceilings. Recently, one of the bedrooms had the temperature spike al the way up to over 90 degrees. I can't seem to get the temperature to come down. The heat is controlled by a Mears single pole thermostat, model M401. The thermostats are from the late 60's to early 70's, but I have never had any trouble with them before. They do no have an "Off" setting, just a temperature range area and a "Low" setting so I can't just shut that room off.
The only thing out of the ordinary that has happened recently is that I spackled and sanded in that room. Is it possible that the electric sander shook something loose in the wall or on the thermostat itself? I don't really know how this stuff works and am looking for any help I can get. Your help is much appreciated.