WILLIS heat pumps: how do their ratings compare?

A typical WILLIS heat pump beats 51% of similar heat pumps (same size and type), which is about average. WILLIS has 15 heat pump models in this list.

Covers older R-410A heat pumps, no longer installed new. See models sold today · Updated Oct 11, 2026

Overall score

51%

of similar heat pumps beaten by its typical model

About average

WILLIS has no QMID (the manufacturer ID the 25C tax credit needs) on file, so it is not ranked against other brands. Based on 20 models with every rating.

WILLIS, rating by ratingStrongest on heating power kept at 5°f (beats 64%), weakest on efficiency on a 5°f day (beats 39%).

Efficiency on a 5°F dayCOP at 5°FBeats 39%
Heating power kept at 5°FCapacity at 5°F vs 47°FBeats 64%
Winter-long heating efficiencyHSPF2Beats 52%
Summer-long cooling efficiencySEER2Beats 55%
Hot-day cooling efficiencyEER2Beats 46%

Average (50%)

Each bar: the share of similar heat pumps a typical model beats on that rating.

Want WILLIS’s ranks and its models inside every size class? Switch to Advanced

Rebate standards

Share of this brand’s models that meet the efficiency levels rebate programs use. Programs can have other rules too.

87%
meet CEE 2025 Tier 1, the level many utility rebates use.
13 models. All brands: 48%.
See them
87%
meet Xcel Energy Colorado’s cold-climate rebate levels.
13 models. All brands: 38%.
See them
0%
reach the cold-climate tier: full heating output and a COP of 2.1 or more at 5°F.
None of its models yet. All brands: 1%.

WILLIS all-around best, by size

Balances heating (5°F output and efficiency, HSPF2) and cooling (SEER2, EER2), each rating against units their size.

Showing Ducted, 2.5–3 tons (27,000–38,999 Btu/h cooling), the most-listed ducted size. Pick yours above. What size is my system?

4 of WILLIS’s 4 models of this size and type have all five ratings.

1MZUHW30KCH21S2-OWILLIS2.5 tons · 28,400 Btu/h · DuctedCold-climate pick, score 54.7Meets CEE 2025, CEE 2026, Xcel CC
Heat kept at 5°F
89% (Capacity at 5°F vs 47°F)
Great
Efficiency at 5°F
1.80 (COP at 5°F)
Below the middle
Winter efficiency
8.1 (HSPF2)
Below the middle
Cooling efficiency
16.0 (SEER2)
Good
Hot-day cooling
11.0 (EER2)
Below the middle
53.1score / 100Heating 55 · Cooling 52
2MZUHW42KCH21S2-OWILLIS3 tons · 36,000 Btu/h · DuctedCold-climate pick, score 52.1Meets CEE 2025, CEE 2026, Xcel CC
Heat kept at 5°F
81% (Capacity at 5°F vs 47°F)
Good
Efficiency at 5°F
1.84 (COP at 5°F)
Below the middle
Winter efficiency
8.1 (HSPF2)
Below the middle
Cooling efficiency
16.0 (SEER2)
Good
Hot-day cooling
11.0 (EER2)
Below the middle
51.8score / 100Heating 52 · Cooling 52
3MZUHW36KCH21S2-OWILLIS3 tons · 34,000 Btu/h · DuctedCold-climate pick, score 50.8Meets CEE 2025, CEE 2026, Xcel CC
Heat kept at 5°F
83% (Capacity at 5°F vs 47°F)
Great
Efficiency at 5°F
1.80 (COP at 5°F)
Below the middle
Winter efficiency
8.1 (HSPF2)
Below the middle
Cooling efficiency
16.0 (SEER2)
Good
Hot-day cooling
11.0 (EER2)
Below the middle
51.1score / 100Heating 51 · Cooling 52
4FLEX24/36KUHwith ducted air handler FLEXAH24/36KWILLIS3 tons · 34,000 Btu/h · DuctedCold-climate pick, score 55.3Meets CEE 2025, CEE 2026, Xcel CC, ENERGY STAR CC
Heat kept at 5°F
80% (Capacity at 5°F vs 47°F)
Good
Efficiency at 5°F
1.80 (COP at 5°F)
Below the middle
Winter efficiency
9.0 (HSPF2)
Good
Cooling efficiency
16.0 (SEER2)
Good
Hot-day cooling
10.0 (EER2)
Below the middle
46.5score / 100Heating 55 · Cooling 38

These are certified test ratings, not a recommendation for your home. The right size comes from a load calculation by a contractor.

What to do next

The advanced view has WILLIS’s ranks on each rating, its models inside every size and type, cold-weather curves and its newest certifications.

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