I have an old (mid 80s) Rheem gas furnace I hope will last me through at least one more California winter. It's been known to go down into the upper fifties, so it has its work cut out for it.
In any case, this is my furnace
Its breaker is on, and there's AC power to it, I've checked.
This is the switch through which its AC power comes in.
(bonus points for who can tell me what that little transformer looking thing below it does – is it related?)
I any case, after a remodel that involved moving the thermostat, I went to plug it back in, and it complained about there being no power on the Rh wire.
Troubleshooting led me back to the furnace itself. I measured DC between the terminals here, but they all read 0v not the 27v I read about and was expecting.
What can I do, am I even in the right place?
Best Answer
Thermostats utilize 24VAC, not DC. If you measure an AC voltage with a DC meter, it will show 0.
I just noticed that ThreePhaseEel posted this answer 16 hours ago as a comment. He/she should get credit for the answer!