O/B Wire Support
A heat pump thermostat has an O or B terminal for the reversing valve. This flips the unit from heat to cool mode. A standard thermostat lacks this.
Thermostat Upgrade for Heat Pumps — Sacramento
Thermostat Upgrade Heat Pump Sacramento
A heat pump with the wrong thermostat wastes energy and wears out fast. Most homeowners never know this until they see their bill.
Why Alex's Cleaning Service?
Book nowWhole-home cleaningDeep cleans, move-ins, move-outs, and upkeep.
3-4 person crewA professional team comes to each visit.
490+ reviews (4.9★ on Google)4.9 average rating across public profiles.
Tucson AreaRoutes from Oro Valley to Vail, Sahuarita, and nearby.
Why Heat Pumps Need a Compatible Thermostat
Heat pumps use an O/B wire to control the reversing valve. Standard thermostats do not have this terminal. If you put a regular thermostat on a heat pump, the unit may heat in cool mode or cool in heat mode. The aux heat strips kick on too often. Your bill goes up. Fresh Air installs the right thermostat with every heat pump we set up in Sacramento.
Aux Heat Lockout
A heat-pump thermostat sets a lockout temp for aux heat. Below that temp, the backup heat strips turn on. Above it, the heat pump handles the load alone.
Fresh Air Includes Thermostat
Every heat pump we install comes with a matched thermostat. We set the O/B mode, aux lockout, and schedule before we leave your home.
What We Check and Set Up
- Confirm your current thermostat has O/B terminal support for heat pump control.
- Set reversing valve mode so the unit heats and cools on the right call.
- Program aux heat lockout to the right outdoor temp for Sacramento climate.
- Test both heat and cool modes before we leave the job.
- Explain the thermostat display so you know what each mode means.
What Goes Wrong With the Wrong Thermostat
Many contractors install a heat pump but leave the old thermostat in place. The old unit may not have an O terminal. The reversing valve defaults to one mode. The heat pump heats when you want cool or cools when you want heat. You call for service and no one can find the fault because the unit tests fine at the outdoor coil.
Setting aux heat lockout wrong also wastes energy. If the lockout is too high, the backup strips run on mild days when the heat pump alone could do the job. On a Sacramento winter day at 38 degrees, the heat pump should still handle most of the load without strips. Fresh Air sets this correctly on every heat pump job and holds CSLB #945361.
Sources
- Best Thermostats for Heat Pumps: Aux Lockout and Cold Climate — thetechinfluencer.com (checked June 15, 2026)
- Replace Heat Pump Thermostat: Guide to Upgrade and Install — qualityhomeaircare.com (checked June 15, 2026)
- Heat Pump Thermostat Wiring — genzryan.com (checked June 15, 2026)
Thermostat Upgrade Heat Pump Sacramento FAQ
Can I use a Nest or Ecobee on my heat pump?
Yes, but only if the model supports O/B wiring. Most current Nest and Ecobee units do. We confirm compatibility before we order and set it up on install day.
What is the aux heat lockout setting?
It is the outdoor temp below which the backup strips can run. Above that temp, the heat pump handles the load alone. We set this based on your unit and Sacramento's typical winter temps.
Does my old thermostat work with a new heat pump?
Probably not. Old thermostats often lack the O terminal needed for heat pump control. We swap it as part of every heat pump job at no surprise cost.
How do I know if my thermostat is set up wrong for my heat pump?
Signs include high bills in mild weather, aux heat running on warm days, or the unit cooling when you want heat. Call us for a check at (916) 416-8181.
Get a Heat Pump Thermostat Check or Setup
Call Fresh Air at (916) 416-8181 or use our contact page. We serve Sacramento, Roseville, Folsom, Elk Grove, and the greater Sacramento Valley. Free in-home estimate. Licensed CSLB #945361.