ZERO heat pump efficiency: 69 outdoor models compared

ZERO has 69 heat pump outdoor models certified with this refrigerant group, in 89 AHRI-certified combinations. Each model is compared with models of the same size and duct type, so the scores below do not depend on which sizes ZERO makes. ZERO has no QMID (IRS Qualified Manufacturer ID) on file, so it is not ranked against other manufacturers.

New to heat pump ratings? The Simple view explains them in plain words →

ManufacturerData as of Oct 11, 2026updated Oct 11, 2026 · sources

Outdoor models: 69
AHRI certifications: 89
Efficiency index: 49%; Typical model vs same-size, same-type peers (62 models)
Meet CEE 2025: 59.4%; 41 models

How ZERO compares with comparable models

For each rating: the share of same-size, same-type models that a typical model of this manufacturer beats (50% is typical), its rank, and the raw median for context. Raw medians are not comparable across manufacturers that make different sizes.

ZERO against every ranked manufacturerPeer scores, 0–100 · grey ticks: each ranked manufacturer · shaded: the middle half of ZERO’s own modelsZERO is strongest on SEER2 (its typical model beats 53% of comparable models) and weakest on capacity retention at 5°F (43%).

ZERO
Middle half of its models
Other ranked manufacturers

Source: AHRI Directory, NEEP · as of Oct 11, 2026

Average peer percentile of ZERO’s models
Rating	Beats comparable models	Rank	Raw median
Efficiency index62 models scored	49%	Not ranked	—
COP at 5°F62 models scored	48%	Not ranked	1.89
Capacity retention at 5°F62 models scored	43%	Not ranked	70%
HSPF277 models scored	46%	Not ranked	8.6
SEER277 models scored	53%	Not ranked	19.0
EER277 models scored	46%	Not ranked	11.0
Heating capacity at 5°F62 models scored	44%	Not ranked	11,700 Btu/h

Standards met

Share of ZERO’s models with at least one qualifying certification
Standard	Share	Models
CEE 2025 Tier 1 (Split ASHP)	59.4%	41
CEE 2026 Tier 1 (Split ASHP)	55.1%	38
CEE Advanced Tier (Split ASHP)	0%	0
Xcel Energy Colorado cold-climate ASHP (2025)	47.8%	33
DOE Cold Climate Heat Pump Challenge	0%	0
ENERGY STAR Cold Climate	24.6%	17

Sizes and duct types offered

Models per peer group, and how they score against the other models of that group.

ZERO’s models inside each size and duct typeShape: every model of the group · blue: the middle half of this manufacturer’s models there, median dot, 10th–90th percentile line

ZERO (median, middle 50%, 10th–90th)
All models of the group

Source: AHRI Directory · as of Oct 11, 2026

Share of comparable models beaten, per peer group
Size and duct type	Models	Index	COP@5°F	HSPF2	SEER2
Ducted, up to 1.5 tons	2	59%	51%	40%	39%
Ducted, 2 tons	5	69%	55%	48%	59%
Ducted, 2.5–3 tons	7	57%	41%	49%	55%
Ducted, 3.5–4.5 tons	9	63%	57%	42%	54%
Ducted, 5 tons and up	1	57%	57%	70%	88%
Non-ducted, up to 1.5 tons	33	48%	47%	47%	52%
Non-ducted, 2 tons	9	49%	48%	49%	56%
Non-ducted, 2.5–3 tons	8	39%	41%	34%	50%
Non-ducted, 3.5–4.5 tons	3	50%	68%	61%	48%

Every ZERO model in the market

ZERO’s 77 models with a known size and duct type, over the shape of the whole catalog.

ZERO models by size and ratingColoured: ZERO · grey shapes: all 11,475 models · lines: catalog medians by size

ZERO models
Ducted median by size
Non-ducted median by size
Every model at each size (width = count)
Standard threshold

Dots: 77 zero models, each through its representative certification, in the colour of the rating shown. The grey shapes count all 11,475 models, half a ton at a time.

Show the data as a table

COP at 5°F by size and duct type (every model, by rated cooling capacity)
Duct type, size	Models	10th pct.	25th	Median	75th	90th
Ducted, 0.5 tons	175	1.70	1.85	1.90	2.10	2.26
Ducted, 1 ton	340	1.85	1.90	2.00	2.40	2.65
Ducted, 1.5 tons	789	1.75	1.85	2.00	2.20	2.55
Ducted, 2 tons	782	1.73	1.80	2.00	2.10	2.33
Ducted, 2.5 tons	735	1.71	1.80	1.90	2.09	2.48
Ducted, 3 tons	652	1.68	1.70	1.90	2.06	2.36
Ducted, 3.5 tons	641	1.61	1.80	1.95	2.20	2.50
Ducted, 4 tons	367	1.70	1.80	1.91	2.02	2.52
Ducted, 4.5 tons	544	1.70	1.80	1.91	2.08	2.34
Ducted, 5 tons	25	1.80	1.80	1.90	1.90	2.15
Non-ducted, 0.5 tons	717	1.75	1.81	1.97	2.10	2.19
Non-ducted, 1 ton	1,064	1.75	1.80	1.90	2.07	2.25
Non-ducted, 1.5 tons	886	1.80	1.80	1.87	2.07	2.21
Non-ducted, 2 tons	564	1.80	1.80	1.83	2.04	2.21
Non-ducted, 2.5 tons	275	1.80	1.81	1.84	1.86	2.03
Non-ducted, 3 tons	502	1.80	1.80	1.90	2.00	2.09
Non-ducted, 3.5 tons	70	1.82	1.83	1.90	2.00	2.28
Non-ducted, 4 tons	263	1.80	1.80	1.98	2.00	2.10
Non-ducted, 4.5 tons	103	1.77	1.77	1.80	1.97	2.02
Non-ducted, 5 tons	29	1.98	2.00	2.10	2.30	2.47

Source: AHRI Directory · as of Oct 11, 2026

Top ZERO models

Its top five cold-climate picks and its top five all-around models across sizes (both scores compare each model with models of its own size and duct type, so sizes compare), then, on each single rating, the model that beats the largest share of comparable models.

Cold-climate picks

Top 5 ZERO cold-climate picks across sizes. Qualifies when its capacity retention at 5°F (capacity at 5°F as a share of capacity at 47°F) is at least 70% and Capacity retention at 5°F, COP at 5°F, HSPF2 are all rated. Score = the equal-weight mean of its peer percentiles on Capacity retention at 5°F, COP at 5°F, HSPF2 (share of the other models in its peer group it beats, 0–100), all from one certified pairing: in each duct type a model is sold in, its qualifying pairing of that type with the best score; equal scores (one decimal) go to the higher heating capacity at 5°F.
# · Outdoor model	Size · type	Cap. 5/47	COP@5°F	HSPF2	Btu/h @5°F	SEER2	Meets	Combos	AHRI ref.	Compared with	Score
1ZMSB-09HV-USHHZERO · ZMSB Serieswith ductless indoor unit ZMSB-09HV-USHH	1 ton9,000 Btu/h · Non-ducted	86%	2.22	11.6	8,564	24.0	CEE 25CEE 26XcelES CC	1	213917748	Non-ducted, up to 1.5 tons	86.0
2Z5SOV-48HDM-USZERO · Z5SOV Series	4 tons48,000 Btu/h · Non-ducted	92%	2.00	10.0	45,000	21.2	CEE 25CEE 26XcelES CC	3	213732668	Non-ducted, 3.5–4.5 tons	80.5
3ZSOV-24HDM-USZERO · ZMSB Serieswith ducted air handler ZDV-24HDM-US	2 tons23,000 Btu/h · Ducted	80%	2.30	11.2	20,000	19.0	CEE 25CEE 26XcelES CC	3	212928560	Ducted, 2 tons	80.3
4ZMSB-12HV-USHHZERO · ZMSB Serieswith ductless indoor unit ZMSB-12HV-USHH	1 ton12,000 Btu/h · Non-ducted	74%	2.25	10.8	8,820	23.1	CEE 25CEE 26XcelES CC	1	213917749	Non-ducted, up to 1.5 tons	77.8
5ZMSB-18HV-USHHZERO · ZMSB Serieswith ductless indoor unit ZMSB-18HV-USHH	1.5 tons18,000 Btu/h · Non-ducted	71%	2.35	10.5	12,829	24.0	CEE 25CEE 26XcelES CC	1	213917750	Non-ducted, up to 1.5 tons	75.3

All-around best

Top 5 ZERO models on the all-around score across sizes. Score = 50% heating, the mean of its peer percentiles on COP at 5°F, Capacity retention at 5°F, HSPF2, plus 50% cooling, the mean of its peer percentiles on SEER2 and EER2 (share of the other models in its peer group it beats, 0–100). All five ratings are required; there is no minimum heat kept at 5°F. In each duct type a model is sold in, it is scored on its pairing of that type with the best score; equal scores (one decimal) go to the higher cold-climate score, then the higher heating capacity at 5°F.
# · Outdoor model	Size · type	Cap. 5/47	COP@5°F	HSPF2	SEER2	EER2	Meets	Combos	AHRI ref.	Compared with	Score	Heating half	Cooling half	Cold-climate score
1ZMSB-09HV-USHHZERO · ZMSB Serieswith ductless indoor unit ZMSB-09HV-USHH	1 ton9,000 Btu/h · Non-ducted	86%	2.22	11.6	24.0	14.7	CEE 25CEE 26XcelES CC	1	213917748	Non-ducted, up to 1.5 tons	86.7	86.0	87.5	86.0
2ZMSB-09HV-USHHCZERO · ZMSB Serieswith ductless indoor unit ZMSB-09HV-USHHCAlso listed as ZMSB-09HV-USHHC-O	1 ton9,000 Btu/h · Non-ducted	94%	1.90	11.6	26.4	15.8	CEE 25CEE 26XcelES CC	1	214232447	Non-ducted, up to 1.5 tons	84.4	74.8	94.1	74.8
3ZSOV-24HDM-USZERO · ZMSB Serieswith ducted air handler ZDV-24HDM-US	2 tons23,000 Btu/h · Ducted	80%	2.30	11.2	19.0	12.5	CEE 25CEE 26XcelES CC	3	212928560	Ducted, 2 tons	83.8	80.3	87.4	80.3
4Z5SOV-48HDM-USZERO · ZMSB Series	4 tons47,000 Btu/h · Ducted	87%	2.00	9.0	20.9	11.7	CEE 25CEE 26XcelES CC	3	213732669	Ducted, 3.5–4.5 tons	82.0	74.9	89.1	74.9
5ZMSB-18HV-USHHZERO · ZMSB Serieswith ductless indoor unit ZMSB-18HV-USHH	1.5 tons18,000 Btu/h · Non-ducted	71%	2.35	10.5	24.0	13.5	CEE 25CEE 26XcelES CC	1	213917750	Non-ducted, up to 1.5 tons	78.7	75.3	82.1	75.3

Best model on each rating

ZERO’s model with the highest peer percentile on each rating, ranked by that one rating only
Rating	Model	Value	Compared with	Beats	AHRI ref.
COP at 5°F	ZMSB-24HV-USHH	2.22	Non-ducted, 2 tons	96%	213917751
Capacity retention at 5°F	Z5SOV-48HDM-US	87%	Ducted, 3.5–4.5 tons	84%	213732669
HSPF2	ZSOV-24HDM-US	11.2	Ducted, 2 tons	98%	212928560
SEER2	Z5SOV-48HDM-US	20.9	Ducted, 3.5–4.5 tons	99%	213732669
EER2	ZMSB-09HV-USHHCAlso listed as ZMSB-09HV-USHHC-O	15.8	Non-ducted, up to 1.5 tons	95%	214232447
Heating capacity at 5°F	ZMSB-18HV-USHHCAlso listed as ZMSB-18HV-USHHC-O	17,200 Btu/h	Non-ducted, up to 1.5 tons	90%	214232449

All 69 ZERO models in Explore

ZERO size class by size class: cold-climate and all-around

Its best model on each board in every size and duct type it makes. Both scores are 0–100 against every model of that size class (the line on each bar is 50, the typical model there). Cold-climate picks must keep at least 70% of their heat at 5°F; the all-around score needs all five ratings and has no such bar.

ZERO: best cold-climate pick and best all-around model per size and duct type, with how many of its models are on each board (top 5 and 5 per class are in the snapshot)
Size and duct type	Cold-climate pickCold-climate score, best model	All-around bestAll-around score, best model
Ducted, up to 1.5 tons	52.0(50 is the typical model of its size class)Z3SOV-18HDM-US1 of 2 models qualify · AHRI 214723150	59.4(50 is the typical model of its size class)Z3SOV-18HDM-US1 of 2 models have all five ratings · AHRI 214723150
Ducted, 2 tons	80.3(50 is the typical model of its size class)ZSOV-24HDM-USwith ducted air handler ZDV-24HDM-US2 of 5 models qualify · AHRI 212928560	83.8(50 is the typical model of its size class)ZSOV-24HDM-USwith ducted air handler ZDV-24HDM-US2 of 5 models have all five ratings · AHRI 212928560
Ducted, 2.5–3 tons	57.4(50 is the typical model of its size class)Z3SOV-27HDM-US1 of 7 models qualify · AHRI 213732663	71.5(50 is the typical model of its size class)Z3SOV-27HDM-US3 of 7 models have all five ratings · AHRI 213732663
Ducted, 3.5–4.5 tons	74.9(50 is the typical model of its size class)Z5SOV-48HDM-US1 of 9 models qualify · AHRI 213732669	82.0(50 is the typical model of its size class)Z5SOV-48HDM-US2 of 9 models have all five ratings · AHRI 213732669
Ducted, 5 tons and up	None on this board (0 of 1 models qualify)	57.1(50 is the typical model of its size class)ZSOV-60HDM-USwith ducted air handler ZDV-60HDM-US1 of 1 models have all five ratings · AHRI 212928563
Non-ducted, up to 1.5 tons	86.0(50 is the typical model of its size class)ZMSB-09HV-USHHwith ductless indoor unit ZMSB-09HV-USHH24 of 33 models qualify · AHRI 213917748	86.7(50 is the typical model of its size class)ZMSB-09HV-USHHwith ductless indoor unit ZMSB-09HV-USHH33 of 33 models have all five ratings · AHRI 213917748
Non-ducted, 2 tons	74.2(50 is the typical model of its size class)ZSOV-24HDM-USwith ductless indoor unit ZEV-24HDM-US4 of 9 models qualify · AHRI 212928564	72.0(50 is the typical model of its size class)ZSOV-24HDM-USwith ductless indoor unit ZEV-24HDM-US9 of 9 models have all five ratings · AHRI 212928564
Non-ducted, 2.5–3 tons	49.3(50 is the typical model of its size class)Z3SOV-27HDM-US1 of 8 models qualify · AHRI 213732662	66.7(50 is the typical model of its size class)Z3SOV-27HDM-US8 of 8 models have all five ratings · AHRI 213732662
Non-ducted, 3.5–4.5 tons	80.5(50 is the typical model of its size class)Z5SOV-48HDM-US2 of 3 models qualify · AHRI 213732668	73.8(50 is the typical model of its size class)Z5SOV-48HDM-US3 of 3 models have all five ratings · AHRI 213732668

All-around board, every manufacturer

Newest ZERO certifications

By AHRI reference number; AHRI issues references in increasing order.

The 5 most recently certified ZERO outdoor models
Outdoor model	Size · type	COP@5°F	Cap. 5/47	HSPF2	SEER2	Meets	Combos	AHRI ref.
ZSOU-24HDG-HYPERZERO · ZSOU Serieswith ducted air handler ZSVF-24HDG-HYPER	2 tons24,000 Btu/h · Ducted	1.90	72%	8.1	18.0	CEE 25CEE 26Xcel	1	217493443
ZPRV16HPBY-NAZERO	4.5 tons54,000 Btu/h · Ducted	—	—	7.2	16.3	None	1	215382818
ZPRV14HPBY-NAZERO	4 tons47,000 Btu/h · Ducted	—	—	7.2	16.7	None	1	215382817
ZPRV10HPBY-NAZERO	2.5 tons32,200 Btu/h · Ducted	—	—	7.4	16.0	None	1	215382816
ZPRV07HPBY-NAZERO	2 tons24,000 Btu/h · Ducted	—	—	7.3	16.2	None	1	215382815

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Manufacturers of a similar size, side by side.

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ZERO includes these brand names as listed in AHRI: ZERO. Standards are checked against published thresholds; program rules beyond ratings are not checked.