Thermostat Repair

[jamina1]

I recently bought a new thermostat for my Heat Pump system and I want to install it. Problem is, that I've turned off EVERY breaker in my circuit box and I still get numbers on my thermostat. I turned off the "HEAT" breaker, and the system doesn't come on if you mess with the thermostat, but I don't want to pull at any wires if there's still power to it.

Is there another breaker outside? (its a heat pump system with emergency heat) Is it safe to change the thermostat, even if I still have numbers on the LCD? is it REALLY that much electricity?

[professorpaul]

The new "setback" thermostats have an internal battery. Check the instructions. My heat pumps (code issue, I believe) have disconnects outside, as well as going through a breaker on the inside, which is well marked.

[jamina1]

The original thermostat doesn't have room for a battery, so its running straight from AC, unless its BEHIND the circuit board and I have to unscrew it from the wall first (doubtful) The thermostat I'm replacing is a White Rodgers Model. Looks to be original, thought the furnace is new. WAIT! I just discovered another breaker in the furnace closet. Will THIS turn off the thermostat even though it appears to be for the furnace only? I don't want to just switch it off and on a bunch of times.

[HeyBub]

New? No doubt it is a bit of film with printed numbers used to simulate an installed thermostat.

Peel it off.

[hallerb]

turn off main breaker killing power in entire home.

[lee houston]

Well, did turning that breaker off, kill the LCD display? Since you said you had a heat pump, I assume by furnace you mean the Air Handler? Many thermostats are powered by a stepdown transformer in or near the air handler. I recommend that you open the thermostat panel and measure the voltage on the wires. your new Thermostat MUST match this voltage.

lee

[mm]

So did the setback thermostat I bought 23 years ago. IIRC, I've only replaced it once, because if the AC power is on, the battery isn't needed. And my thermostat has mechanical switches for the times of day, the day and night temps, and the days that there should be 2 setbacks instead of 1. So all the battery does is keep the time, when the AC is off.

More below

I wish I could help you more, but I do want to ask, If you are willing to turn the power off altogether, why do you not want to turn it off and on a few times for the sake of testing?

[souperman]

Or better yet, call the power company and tell them there is a terrorist living next door and he has a large bomb hooked to the the electrical system, and would they please shut down the power to the entire city...... They will shut it down quickly, and when the police arrive they ought to be happy to commit you to the psycho ward. But before the cops arrive, you can safely install your thermostat without getting a shock off that AA battery.