Can I Replace My Own Thermostat?

Short answerOften yes in our view, on a common low-voltage system, by following the new thermostat's instructions. Honeywell's guide says to disconnect power first, because of shock and equipment risk. If your old thermostat holds mercury, don't throw it in the trash. If you have electric baseboard heat or aren't sure of the voltage, we recommend an electrician or HVAC technician.

What this costs

Our national estimates, not quotes.
Option	Job	Low	High
Replace	Thermostat Replacement	$100	$510

Check these first

Compatibility: use the maker's guide for your system type.
Power: Honeywell's caution says to disconnect power before installation to avoid shock or equipment damage.
Voltage: if you don't know what voltage your system uses, stop and ask an electrician or HVAC technician. Don't judge it by how the wires look. That's our own advice, not from the guide.

The mercury rule

If the old unit has a small sealed tube, it may contain mercury. Honeywell's guide says not to place it in the trash, and to call your local waste management authority. EPA says old mercury thermostats need proper disposal and should go to a state or local household hazardous waste collection center.

When not to do it yourself

A permit isn't usually discussed for a thermostat swap in the pages we read, but we didn't confirm it, so ask locally if you're moving wiring.

You're unsure what voltage the system uses.
It has many wires and a heat pump or zones, and the new unit's instructions don't clearly match.
You've got no heat or cooling and the thermostat isn't the obvious cause.
There's any sign of gas or burning. If you smell gas, leave first.

Where it goes matters

NC State Extension says a thermostat should be in a central location, away from doors and windows. DOE adds that lamps and TVs nearby make the AC run longer. We expect moving one means new wiring, which is a bigger job than a swap.

Thermostat Not Working? Blank Screen and Other Fixes

Common questions

Can I replace a thermostat with the power on?

Don't. Honeywell's guide says to disconnect power before beginning installation, since it can cause shock or equipment damage.

Can I replace my thermostat in an apartment?

We recommend asking your landlord or building manager first. We expect the system and thermostat usually aren't yours to change, and your lease may cover it.