What this covers
A thermostat is the control for the whole system, and installing one correctly means matching it to the equipment: single-stage or multi-stage, heat pump with backup heat, humidifier or fresh-air controls. The installer checks the existing wiring and the presence of a common wire that most smart thermostats need, adds one or a power adapter where it is missing, mounts the base level on the wall, lands the wires by function, and configures the thermostat for the equipment type, cycle rates and any backup-heat lockout. The company then runs each mode, connects the thermostat to your home network if it is a smart model, and shows you how schedules and remote control work.
When to call
- A thermostat that reads far from the room temperature or cycles the system too often.
- A new furnace, air conditioner or heat pump that needs a compatible control.
- A wish for schedules, remote control or usage reports from your phone.
- A second zone that needs its own control.
What to expect
- Check compatibilityThe equipment type, the number of wires and the presence of a common wire decide which thermostats fit.
- WireThe old thermostat comes off, wires are labeled by function, a common wire or adapter is added if needed, and the base is mounted level.
- ConfigureEquipment type, staging, backup-heat lockout and cycle rates are set for the system.
- Walk throughHeating, cooling and fan are run, the network connected if it is a smart model, and you learn the schedules.
Get a certified company
Look up a certified company by ZIP code. Every company's license, insurance and trades are verified before it is listed, and placement is never paid.
Questions people ask
What is a common wire?
A fifth wire that supplies power to the thermostat. Many older homes have four wires, and smart thermostats need the common wire or an adapter at the furnace to run reliably.
Where should the thermostat go?
On an interior wall, away from sun, drafts, lamps and kitchens, at about chest height in a room you use. A poor location makes a good thermostat misread the house.
Can a smart thermostat run a heat pump?
Yes, if it is set up for one. The installer configures the reversing valve type and the backup heat so the strips or furnace do not run when the heat pump alone would do.
Related: Furnace installation · Air conditioner installation · Heat pump installation · All heating, cooling and air quality
This page describes what the service involves. The company you hire sets the scope, the schedule and the price, and your contract is with that company. We verify credentials and collect reviews from real jobs. We do not guarantee any company's workmanship. Safety steps are general guidance. When in doubt, leave the home and call 911.