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ACD vs ZEPHYR heat pumps

Measured against models of the same size and duct type, ACD scores higher on 3 of the 6 ratings. ACD has 25 outdoor models, ZEPHYR has 25 outdoor models. ACD and ZEPHYR have no QMID on file and are not ranked.

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CompareData as of updated · sources

Against comparable models

Each cell is the share of same-size, same-type models that the manufacturer’s typical model beats (50% is typical); the higher score is in bold. Raw medians are underneath for context: they depend on which sizes each one makes, so they are not compared.
ACD and ZEPHYR on every ratingPeer scores, 0–100 · grey ticks: every ranked manufacturer · shaded: the middle half of each one’s modelsMeasured against models of the same size and duct type, ACD scores higher on 3 of the 6 ratings.
  • ACD
  • ZEPHYR
  • Other ranked manufacturers
ACDZEPHYR

Source: AHRI Directory, NEEP · as of

Average peer percentile, raw median and rank among ranked manufacturers
RatingACDZEPHYR
Efficiency index51%median —58%median —
COP at 5°F36%median 1.8240%median 1.87
Capacity retention at 5°F69% (higher)median 78%68% (higher)median 80%
HSPF247% (higher)median 9.043% (higher)median 9.0
SEER253%median 20.053%median 21.0
EER251%median 12.052%median 12.5
Heating capacity at 5°F67% (higher)median 21,600 Btu/h63% (higher)median 16,200 Btu/h
Outdoor models2525
AHRI certifications5131

Share of models meeting each standard

Percent of each manufacturer’s models with a qualifying certification
StandardACDZEPHYR
CEE 2025 Tier 1 (Split ASHP)88%22 models76%19 models
CEE 2026 Tier 1 (Split ASHP)84%21 models76%19 models
CEE Advanced Tier (Split ASHP)0%0 models0%0 models
Xcel Energy Colorado cold-climate ASHP (2025)88%22 models76%19 models
DOE Cold Climate Heat Pump Challenge0%0 models0%0 models
ENERGY STAR Cold Climate72%18 models36%9 models

Sizes and duct types offered

Models in each peer group, with the efficiency index of those models against the rest of the group.
Side by side, inside each size and duct typeShape: every model of the group · bars: each manufacturer’s middle half, median dot, 10th–90th line · 7 groups where both have models
  • ACD
  • ZEPHYR
  • All models of the group
Ducted, up to 1.5 tons2.00884 modelsDucted, 2 tons2.00821 modelsDucted, 2.5–3 tons1.901,614 modelsDucted, 3.5–4.5 tons1.911,492 modelsNon-ducted, up to 1.5 tons1.902,417 modelsNon-ducted, 2 tons1.87611 modelsNon-ducted, 2.5–3 tons1.85975 modelsNon-ducted, 3.5–4.5 tons1.97438 modelsmedian

Raw ratings are only placed side by side within one size and duct type, where they are comparable.

Source: AHRI Directory · as of

Models per peer group · efficiency index within the group
Size and duct typeACDZEPHYR
Ducted, up to 1.5 tons1 · index 31%None
Ducted, 2 tons2 · index 53%1 · index 46%
Ducted, 2.5–3 tons3 · index 52%1 · index 63%
Ducted, 3.5–4.5 tons1 · index 63%2 · index 51%
Non-ducted, up to 1.5 tons11 · index 51%15 · index 58%
Non-ducted, 2 tons5 · index 54%4 · index 62%
Non-ducted, 2.5–3 tons6 · index 54%1 · index 70%
Non-ducted, 3.5–4.5 tons1 · index 19%1 · index 45%

Cold-climate and all-around picks, size class by size class

Each manufacturer’s best model on each board in every size and duct type, side by side; the higher score is in bold. Both scores are 0–100 against every model of that size class (the line on each bar is 50, the typical model there), so the two compare fairly even when they make different sizes.

Cold-climate picks

Best cold-climate pick per size and duct type (keeps at least 70% of its heat at 5°F). 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.
Size and duct typeACDCold-climate score, best modelZEPHYRCold-climate score, best model
Ducted, up to 1.5 tons35.6(50 is the typical model of its size class)MPD18KCH21SB-O1 of 1 models qualify · AHRI 210534132No models in this size class
Ducted, 2 tons50.1(50 is the typical model of its size class)MPD24KCH21SB-O1 of 1 models qualify · AHRI 21053413357.5(50 is the typical model of its size class) (higher)ZE-24HPBwith ducted air handler AH-24B1 of 1 models qualify · AHRI 207036640
Ducted, 2.5–3 tons55.3(50 is the typical model of its size class)FXD-ACD36with ducted air handler AH2364 of 4 models qualify · AHRI 20749790275.1(50 is the typical model of its size class) (higher)ZE-36HPBwith ducted air handler AH-36B1 of 1 models qualify · AHRI 207036642
Ducted, 3.5–4.5 tons58.1(50 is the typical model of its size class) (higher)FXD-ACD60with ducted air handler AH2481 of 1 models qualify · AHRI 20749790356.6(50 is the typical model of its size class)ZE-48HPBwith ducted air handler AH-48B1 of 2 models qualify · AHRI 207036646
Non-ducted, up to 1.5 tons80.1(50 is the typical model of its size class) (higher)UHD09KCH38SB-Owith ductless indoor unit UHD09KCH38SB-I10 of 11 models qualify · AHRI 20240983272.9(50 is the typical model of its size class)ZE-09UH24SCOwith ductless indoor unit ZE-09UH24SCI11 of 15 models qualify · AHRI 208287539
Non-ducted, 2 tons76.1(50 is the typical model of its size class) (higher)MPD24KCH21SB-O4 of 5 models qualify · AHRI 21053412864.0(50 is the typical model of its size class)ZE-24CA22SEXTwith ductless indoor unit ZE-24CA22SINT3 of 4 models qualify · AHRI 203446804
Non-ducted, 2.5–3 tons73.7(50 is the typical model of its size class) (higher)MPD42KCH21SB-O6 of 6 models qualify · AHRI 21053413164.0(50 is the typical model of its size class)ZE-36M422SCO1 of 1 models qualify · AHRI 206347270
Non-ducted, 3.5–4.5 tons31.6(50 is the typical model of its size class)MUD42KCH23S-O1 of 1 models qualify · AHRI 20642858741.9(50 is the typical model of its size class) (higher)ZE-42M522SCO1 of 1 models qualify · AHRI 206346135

All-around best

Best all-around model per size and duct type. 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.
Size and duct typeACDAll-around score, best modelZEPHYRAll-around score, best model
Ducted, up to 1.5 tons31.2(50 is the typical model of its size class)MPD18KCH21SB-O1 of 1 models have all five ratings · AHRI 210534132No models in this size class
Ducted, 2 tons60.8(50 is the typical model of its size class) (higher)FXD-ACD36with ducted air handler AH2242 of 2 models have all five ratings · AHRI 20749790146.3(50 is the typical model of its size class)ZE-24HPBwith ducted air handler AH-24B1 of 1 models have all five ratings · AHRI 207036640
Ducted, 2.5–3 tons53.1(50 is the typical model of its size class)MPD30KCH21SB-O3 of 3 models have all five ratings · AHRI 21053413463.2(50 is the typical model of its size class) (higher)ZE-36HPBwith ducted air handler AH-36B1 of 1 models have all five ratings · AHRI 207036642
Ducted, 3.5–4.5 tons63.3(50 is the typical model of its size class) (higher)FXD-ACD60with ducted air handler AH2481 of 1 models have all five ratings · AHRI 20749790357.3(50 is the typical model of its size class)ZE-48HPBwith ducted air handler AH-48B2 of 2 models have all five ratings · AHRI 207036646
Non-ducted, up to 1.5 tons88.7(50 is the typical model of its size class) (higher)UHD09KCH38SB-Owith ductless indoor unit UHD09KCH38SB-I11 of 11 models have all five ratings · AHRI 20240983281.4(50 is the typical model of its size class)ZE-09UH24SCOwith ductless indoor unit ZE-09UH24SCI11 of 15 models have all five ratings · AHRI 208287539
Non-ducted, 2 tons76.3(50 is the typical model of its size class) (higher)UHD24KCH22S-Owith ductless indoor unit UHD24KCH22S-I5 of 5 models have all five ratings · AHRI 20213278967.5(50 is the typical model of its size class)ZE-24M322SCO3 of 4 models have all five ratings · AHRI 206346130
Non-ducted, 2.5–3 tons70.2(50 is the typical model of its size class) (higher)MPD42KCH21SB-O6 of 6 models have all five ratings · AHRI 21053413169.5(50 is the typical model of its size class)ZE-36M422SCO1 of 1 models have all five ratings · AHRI 206347270
Non-ducted, 3.5–4.5 tons18.7(50 is the typical model of its size class)MUD42KCH23S-O1 of 1 models have all five ratings · AHRI 20642858744.5(50 is the typical model of its size class) (higher)ZE-42M522SCO1 of 1 models have all five ratings · AHRI 206346134

All-around board, every manufacturer

Standout model on each rating

Each manufacturer’s model that beats the largest share of comparable models on the rating; the higher share is in bold.
Top model per rating by peer percentile, with its AHRI-certified value and peer group
RatingACDZEPHYR
COP at 5°Fbeats 89% · 2.21MPD18KCH21SB-ONon-ducted, up to 1.5 tonsbeats 81% · 2.13ZE-24CA22SEXTNon-ducted, 2 tons
Capacity retention at 5°Fbeats 99% · 144%UHD09KCH38SB-ONon-ducted, up to 1.5 tonsbeats 99% · 113%ZE-36M422SCONon-ducted, 2.5–3 tons
HSPF2beats 88% · 11.0UHD09KCH38SB-ONon-ducted, up to 1.5 tonsbeats 83% · 9.5ZE-36HPBDucted, 2.5–3 tons
SEER2beats 95% · 27.0UHD09KCH38SB-ONon-ducted, up to 1.5 tonsbeats 89% · 25.5ZE-09UH24SCONon-ducted, up to 1.5 tons
EER2beats 99% · 16.6UHD09KCH38SB-ONon-ducted, up to 1.5 tonsbeats 89% · 14.5ZE-09UH24SCONon-ducted, up to 1.5 tons
Heating capacity at 5°Fbeats 99% · 21,800 Btu/hMUD18KCH23S-ONon-ducted, up to 1.5 tonsbeats 92% · 18,000 Btu/hZE-18M222SCONon-ducted, up to 1.5 tons

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