Have a weird situation in a condo that I own. Building has oil fired boiler and fin-tube baseboard hot water radiator heat. It seems like a very simple system. While remodeling, I decided to replace the decades old mechanical thermostat with a somewhat more modern Honeywell mechanical. There are only two wires in use and I connected them to the "R" and "W" terminals of the new thermostat. For the first few weeks, everything worked fine. If I set the thermostat to 70 degrees, the room became roughly 70 degrees. However, the other day, I came home and the place was over 80 degrees. For some reason, the thermostat is constantly calling for heat, even if I set it at 50. You can still hear the click when the thermostat is supposed to stop calling for heat, but it has no effect on the actual call for heat. The only way to stop the radiator getting hot is to remove the control unit of the thermostat. I unwired everything again and did some tests. When you short the two wires, you get heat and when you unattach them the heat stops. There must be something wrong with the control unit of the thermostat. Has anyone had this happen? Model T87K1007
This is so weird, because it worked perfectly for two weeks and then just stopped. Could the power stealing nature of these thermostats wreak some havoc at the zone valves in the boiler room? Is it worth me checking out the boiler room?
Oh, that red wire was not connected to anything previously. Also, I decided to put a multi-meter in AC voltage mode between the white and black wires. It read between 7 and 8 volts. Does this mean anything?