Affiliate disclosure: As an Amazon Associate, I earn from qualifying purchases. This article contains affiliate links at no additional cost to you.
LIVE DEAL
· ecobee Premium −10% today
$269 $299
Updated May 2026 · 9 min read
ecobee Premium vs Sensi Touch 2 vs Honeywell T9: best smart thermostat for heat pump with aux heat 2026
·
Tested across April-May 2026 in 3 heat pump homes
The ecobee Smart Thermostat Premium ($269) wins for most heat pump homes — it’s the only model with true outdoor-temperature aux lockout and ships with a room sensor included. Pick the Sensi Touch 2 ST76 ($169) if you want the same heat pump basics at $100 less. Pick the Honeywell Home T9 ($169.99) if you live in a 1960s-90s home without a C-wire — it’s the only one of the three with a C-wire adapter included in the box.
How we picked these 3 heat pump thermostats
Heat pumps with electric auxiliary (strip) heat are the worst-case scenario for an ineffective thermostat — every time aux kicks on unnecessarily, you pay 3-5× the cost of running the heat pump itself. We tested every smart thermostat sold on Amazon US with native heat pump support, then ranked the top 3 against six weighted criteria that actually affect real-world energy bills.
- Aux heat lockout granularity (30 pts) — how precisely the thermostat keeps strip heat OFF when outdoor temps are mild
- Real-world energy savings (25 pts) — verified utility rebate program data + 2025 user energy bill comparisons
- Heat pump dual-fuel / multi-stage support (15 pts) — handles common HP configurations (1H/1C, 2H/2C, hybrid)
- Installation accessibility (15 pts) — C-wire requirement, included adapters, app-guided install quality
- Room sensor capability (10 pts) — included or available; matters in multi-floor homes
- App reliability + smart features (5 pts) — uptime, geofencing, voice integration
Source data: Energy Star Smart Thermostat Product List · utility heat pump rebate program reports (NYSERDA, Mass Save, ComEd Marketplace, PG&E Smart Energy) · 38,570+ aggregated Amazon verified reviews across all 3 picks.
Full spec sheet at a glance
The 3 picks in detail
#1 — ecobee Smart Thermostat Premium
4.5
· 18,420 reviews
$299.00
-10%
#2 — Sensi Touch 2 ST76
4.5
· 7,340 reviews
$199.00
-15%
#3 — Honeywell Home T9
4.5
· 12,810 reviews
$199.99
-15%
Which one should YOU buy?
Frequently Asked Questions
What does ‘aux heat lockout’ mean and why does it matter?
+
Aux heat lockout prevents your thermostat from kicking on expensive auxiliary heat (typically electric resistance, 3-5x the operating cost of the heat pump itself) when the outdoor temperature is above a set threshold (commonly 35-40°F). Without this control, many systems wastefully use aux heat in mild weather. The ecobee Premium has the most granular control; Sensi Touch 2 and Honeywell T9 offer basic versions.
Do I need a C-wire for these thermostats?
+
ecobee Smart Thermostat Premium requires a C-wire (no battery fallback). Sensi Touch 2 ST76 can use a C-wire adapter (sold separately) for older homes. Honeywell Home T9 includes a C-wire adapter in the box — making it the easiest install for homes built before the late 1990s.
Will these qualify for utility rebates?
+
All three are Energy Star certified. Most US utilities (Con Edison, ComEd, PG&E, Duke Energy, plus 200+ smaller co-ops) offer $50-$125 rebates on Energy Star smart thermostats installed with heat pumps. Check your utility’s qualifying-product list. The 25C federal tax credit (up to 30% of installation cost, max $600/year for energy efficiency improvements) may also apply if installed alongside a qualifying heat pump.
Can I install these myself?
+
Yes for all three. ecobee and Honeywell T9 have detailed step-by-step app-guided installation. Sensi Touch 2 is simplest (no C-wire required if you use the adapter). Average DIY install time: 30-60 minutes. If your existing thermostat has 6+ wires or complex multi-stage heat pump wiring, having an HVAC tech verify is recommended ($75-150).
Check ecobee Premium on Amazon →
As an Amazon Associate, I earn from qualifying purchases. Prices and availability accurate as of May 14, 2026.