Hi - I recently purchased my first home built in 1981 with a Robertshaw (model 9620, I think) thermostat. The heater has been working very well over the past month. However, this morning I turned the thermostat up and the heater did not respond (I waited approximately 30 minutes). I turned the thermostat off and on. When I turned it on, it clicked (which I expected it to), but then it began clicking repeatedly and erratically. I immediately turned it off and haven't tried to turn it back on. Can anyone tell me what this might indicate (new thermostat needed, new batteries, etc)? I appreciate the assistance! :)

It could be almost anything but the thermostat is suspect. If this is a gas furnace you can jump the R and W wires on the thermostat or at the furnace and see if the unit comes on. If it works after the jumper thing then you probably have a defective thermostat. Since I have no idea whet you exact setup is it could also be the batterys in the thermostat if so equipped and if the batterys are necessary for proper operation.