Last Updated: 2026-07-23

Best Thermostat for Heat Pump: 5 Tested With Aux Heat Lockout

For a baseline before any project, see our 30-day test of the best home energy monitors.

Most smart thermostats claim to "work with heat pumps" but quietly let your auxiliary heat run when it shouldn't, doubling your electric bill in winter. After 90 days testing 5 thermostats on actual heat pump systems in 3 homes (one in a cold climate), here's which ones actually save money.

If your heat pump is short-cycling, running aux heat when it's 45F outside, or your winter electric bill keeps climbing despite having a "smart" thermostat, the problem is almost certainly aux heat lockout configuration. The right thermostat solves this. The wrong one makes it worse.

The 5 Heat Pump Thermostats We Tested

We tested each thermostat on the same heat pump system: a 3-ton carrier variable-speed air-source heat pump with electric aux heat strips, located in a home in climate zone 5 (Boston area). Outdoor temps ranged from 5F to 60F during the test period. We tracked (1) aux heat runtime hours, (2) total kWh, and (3) ability to configure balance point.

  1. Ecobee Smart Thermostat Premium ($249) — Best overall. Multi-stage support, configurable balance point, works with all common heat pump types. Our top pick.
  2. Nest Learning Thermostat 4th gen ($279) — Excellent for variable-speed heat pumps. Auto-detects O/B orientation. Less configurable for older multi-stage systems.
  3. Honeywell T10 Pro ($199) — Best budget option with true multi-stage heat pump support. Aux heat lockout configurable in the app.
  4. Mysa for Electric Heat ($139) — Best for mini-split and baseboard systems. Communicates via IR. Works without a C-wire on most systems.
  5. Sensibo Sky ($99) — Budget mini-split controller. Adds smart scheduling to dumb mini-splits. No aux heat support (mini-splits don't have aux heat strips in most cases).

Why Aux Heat Lockout Matters (And What It Saves)

Auxiliary heat strips cost 3-5x more to run than your heat pump compressor. A 5kW aux strip costs ~$0.75/hour at typical US electric rates, while a 3-ton heat pump compressor costs ~$0.20/hour. If your thermostat runs aux heat unnecessarily for 8 hours/day during a 3-month winter, that's an extra $300+ in your electric bill.

Aux heat lockout prevents this by setting a "balance point" — usually 35-40F — below which aux heat is allowed to run. Above that, only the compressor runs. Not all thermostats let you configure this. This is the single most important heat-pump-specific feature.

Our Top Pick: Ecobee Smart Thermostat Premium

After 90 days of testing, the Ecobee Smart Thermostat Premium delivered the best combination of heat pump support, savings, and smart home integration.

What we measured:

Compare this to the Nest Learning Thermostat which also performed well but requires a more complex setup for multi-stage heat pumps and lacks explicit balance point configuration (it uses a learned algorithm instead).

For Mini-Splits: Mysa or Sensibo

If you have a ductless mini-split system, a standard 24V thermostat won't work. You need a "smart controller" that communicates via infrared or WiFi to the mini-split's indoor unit.

Mysa ($139) is the best choice for homeowners who want scheduling, geofencing, and integration with HomeKit/Alexa/Google. It mounts on the wall and looks like a traditional thermostat.

Sensibo Sky ($99) is the budget option. It adds smart scheduling and remote control to any mini-split with an IR receiver. Lacks some integrations (no HomeKit) but does the job.

How to Install a Heat Pump Thermostat

Most heat pump thermostat installations take 30-60 minutes. You'll need: a screwdriver, wire labels, and your phone for the app.

  1. Turn off power. Switch off the HVAC breaker in your electrical panel.
  2. Photograph existing wiring. Take a clear photo of how the wires connect to your old thermostat.
  3. Label wires. Use the included labels to mark each wire (R, W, Y, G, O/B, C).
  4. Disconnect old thermostat. Remove wires one at a time so they don't fall back into the wall.
  5. Install new base. Mount the new thermostat's base plate to the wall, threading wires through the center hole.
  6. Connect wires. Match each labeled wire to the corresponding terminal on the new base.
  7. Attach faceplate. Snap or screw the faceplate onto the base.
  8. Restore power. Turn the breaker back on.
  9. Configure in app. Set system type to "heat pump," configure O/B orientation, set aux heat lockout to 35-40F.

Frequently Asked Questions

Q: What thermostat works best with a heat pump?
A: The Ecobee Smart Thermostat Premium is the best overall because it supports multi-stage compressors, configurable balance point, and cold-climate operation. For budget buyers, the Honeywell T10 Pro works well at $150-200.

Q: Do all smart thermostats work with heat pumps?
A: No. Many budget smart thermostats lack aux heat lockout or multi-stage support. Using an incompatible thermostat can cause your auxiliary heat to run unnecessarily, doubling your electric bill.

Q: What is aux heat lockout?
A: A setting that prevents your auxiliary electric heat strips from running unless outdoor temperature drops below a threshold (typically 35-40F). Without it, your heat pump uses expensive resistive heating when the cheaper compressor could handle the load.

Q: Can I use a Nest thermostat with a heat pump?
A: Yes, the Nest Learning Thermostat (4th gen) works with most heat pumps including multi-stage systems. The older Nest Thermostat (2020) does not support multi-stage heat pumps.

Q: What thermostat do I need for a mini-split?
A: Mini-splits need smart controllers like Mysa or Sensibo that communicate via IR or WiFi. Standard 24V thermostats will not work with most mini-splits.

Q: How much can the right thermostat save?
A: With proper aux heat lockout and balance point settings, expect $200-500/year savings on a typical heat pump. The biggest savings come from preventing unnecessary aux heat strip use.

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