I'm replacing my thermostat - where is the electrical power shut off switch to the furnace?

Question

I'm replacing my thermostat (heat only) and the instructions say to turn off the electrical power to the furnace (which I guess shuts off the voltage to the thermostat wires) before removing the wires from the old thermostat and attaching them to the new one.

Trouble is, I've looked around my gas furnace in the basement and I can't figure out where the switch would be. I have a fuse box, I wonder if I should just remove the fuse, and if that would be sufficient?

Sorry, I'm a girl, and this is a bit over my head. But I don't want to spend more money to hire an HVAC guy about this.

THANKS!

I should add that nothing is labeled, including any of the fuses in the fuse box....I would have to unscrew all of them. My landlord is a retard. I asked him to fix the thermostat two months ago, and I'm tired of waiting, so I'm trying to do this myself.

Several people have mentioned looking at my breaker box. I don't have a circuit breaker box...it's a fuse box.

Answer 1

I've changed out my thermostats without turning off the furnace. The control wiring is only 24 volts and is not dangerous.
There should be what looks like a regular light switch on the wall somewhere, most likely with a red wall plate. This should turn off the furnace and control wiring.
If you can't find the switch open the furnace fuse. Open them all or turn off the main service switch for the entire panel if you can't find the right one. That should guarantee the furnace is disabled. If not, someone else may be paying the electric bill for your furnace. I've seen similar wiring messes in apartments before...

Answer 2

If you can't find any way to kill the power, then you should leave it alone. If it were me I would remove the wires one at a time from the thermostat and place a piece of tape over the bare wires, Any kind will work (for 24 volts). I would write the color of the wire and the name (or number) of the terminal I removed it from. remove the old therm. and install the new. I would take the tape off as I put each wire back, but you shouldn't

Answer 3

Power to the thermostat should be 24 volts and comes from the furnace via a transformer. The easiest way to kill the juice to the thermostat is to simply unplug the furnace.....
The reason for de-activating this low voltage is to protect the new t/stat from damage during its installation.

Answer 4

one if the furnace is up to canadian gas codes the on/off switch by code should be near the furnace(within 3 feet). Older furnaces has on/off switches on the furnace or near a door, high up on the wall.
If you have a summer /winter switch turn the furnace on so it blows cold air then got to the fuse box and remove the fuse that turns it off.. then replace the t-stat. black wire on r or rh and white wire on w. there ya go.. youve save an 80.00 call out

Answer 5

go to your breaker box it will say furnace pull the breaker then you can take a electrical tester and check to see if it is off. but if you cant turn it off it really wont heart anything because the wires going to the thermostat are low voltage any way.

Answer 6

The thermostat is low voltage and does not pose a shock hazard, but you should shut down the system before working on the controls to avoid possible damage to the system.

Answer 7

turn on the furnace now remove the door .the furnace schould stop .go change the thermo and reinstall the door .its only 24 volts

Answer 8

There should be 2 switches, both with red cover plates.

One should be at the entrance to your basement or room with the unit.

The other is almost always on the ceiling above the unit (to one side).

Answer 9

Remove the fuse and make sure it is the right one.

Answer 10

and if you don't find it there, look in your breaker box for the breaker labeled "furnace"