Honeywell Chronotherm III. Has been flashing "replace batteries" for a while. I ignored it thinking the batteries are only a backup. However, this morning display was dead and heat was off. I replaced batteries and now everything seems to be working fine. BUT . . . does this mean that the thermostat is not getting its power from the wires? And is it supposed to be? TIA.
You will want to look at the backplate (take thermostat off the subbase) is there a wire connected to C?
Also while you have it off, get the model number. It should start with a T, a CT, or some other letter followed by 4 numbers, a letter and more numbers.
Hello,The model # XXXXX XXXXXThere is no wire connected to C. Actually there's not even a screw there, just a hole, Here is the wiring scheme from left to right:O - screw but no wireW - white wireG - green wireC - holeR - red wireR sub C - jumper to RB - screw but no wireY - black wireI have a gas furnace and central A/C.So it's sounding like this is set up in such a way that it's normal for the controller to be running under battery power only?
Without a Common (C) hooked up, the thermostat will be primarily powered by the batteries. If you have an extra thermostat wire we can walk you through hooking it to the furnace and thermostat.
Thanks, that's all I needed to know.
No problem, thank you for using JustAnswer!