COMFORMATIC vs MAMMOTH heat pumps

Measured against models of the same size and duct type, COMFORMATIC scores higher on 4 of the 6 ratings. COMFORMATIC has 4 outdoor models, MAMMOTH has 4 outdoor models. COMFORMATIC and MAMMOTH have no QMID on file and are not ranked.

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CompareData as of Oct 11, 2026updated Oct 11, 2026 · 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.

COMFORMATIC and MAMMOTH 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, COMFORMATIC scores higher on 4 of the 6 ratings.

COMFORMATIC
MAMMOTH
Other ranked manufacturers

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

Average peer percentile, raw median and rank among ranked manufacturers
Rating	COMFORMATIC	MAMMOTH
Efficiency index	44% (higher)median —	39% (higher)median —
COP at 5°F	37% (higher)median 1.90	15% (higher)median 1.80
Capacity retention at 5°F	64% (higher)median 74%	29% (higher)median 65%
HSPF2	42% (higher)median 9.3	41% (higher)median 8.8
SEER2	44%median 20.5	55%median 17.5
EER2	39%median 11.7	43%median 10.8
Heating capacity at 5°F	64% (higher)median 11,200 Btu/h	32% (higher)median 17,750 Btu/h
Outdoor models	4	4
AHRI certifications	8	8

Share of models meeting each standard

Percent of each manufacturer’s models with a qualifying certification
Standard	COMFORMATIC	MAMMOTH
CEE 2025 Tier 1 (Split ASHP)	50%2 models	50%2 models
CEE 2026 Tier 1 (Split ASHP)	50%2 models	50%2 models
CEE Advanced Tier (Split ASHP)	0%0 models	0%0 models
Xcel Energy Colorado cold-climate ASHP (2025)	50%2 models	50%2 models
DOE Cold Climate Heat Pump Challenge	0%0 models	0%0 models
ENERGY STAR Cold Climate	50%2 models	50%2 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 · 2 groups where both have models

COMFORMATIC
MAMMOTH
All models of the group

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

Source: AHRI Directory · as of Oct 11, 2026

Models per peer group · efficiency index within the group
Size and duct type	COMFORMATIC	MAMMOTH
Ducted, up to 1.5 tons	1 · index 32%	None
Ducted, 2 tons	1 · index 46%	2 · index 49%
Ducted, 2.5–3 tons	None	1 · index 29%
Ducted, 3.5–4.5 tons	None	1 · index 63%
Non-ducted, up to 1.5 tons	3 · index 39%	None
Non-ducted, 2 tons	1 · index 72%	1 · index 20%
Non-ducted, 2.5–3 tons	None	1 · index 21%

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 type	COMFORMATICCold-climate score, best model	MAMMOTHCold-climate score, best model
Ducted, up to 1.5 tons	36.0(50 is the typical model of its size class)GFMCX18-H21 of 1 models qualify · AHRI 212925600	No models in this size class
Ducted, 2 tons	50.1(50 is the typical model of its size class)GFMCX24-H21 of 1 models qualify · AHRI 212925603	None on this board (0 of 1 models qualify)
Ducted, 2.5–3 tons	No models in this size class	55.3(50 is the typical model of its size class)GXH24-36MSK4DHwith ducted air handler GMH**-36MSK4DH11 of 2 models qualify · AHRI 206724413
Ducted, 3.5–4.5 tons	No models in this size class	58.1(50 is the typical model of its size class)GXH48-60MSK4DHwith ducted air handler GMH48-**MSK4DH11 of 1 models qualify · AHRI 206724414
Non-ducted, up to 1.5 tons	73.4(50 is the typical model of its size class)GFMCX18-H23 of 3 models qualify · AHRI 212925599	No models in this size class
Non-ducted, 2 tons	76.1(50 is the typical model of its size class)GFMCX24-H21 of 1 models qualify · AHRI 212925602	None on this board (0 of 1 models qualify)
Non-ducted, 2.5–3 tons	No models in this size class	None on this board (0 of 1 models qualify)

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 type	COMFORMATICAll-around score, best model	MAMMOTHAll-around score, best model
Ducted, up to 1.5 tons	31.5(50 is the typical model of its size class)GFMCX18-H21 of 1 models have all five ratings · AHRI 212925600	No models in this size class
Ducted, 2 tons	45.9(50 is the typical model of its size class)GFMCX24-H21 of 1 models have all five ratings · AHRI 212925603	60.8(50 is the typical model of its size class) (higher)GXH24-36MSK4DHwith ducted air handler GMH24-**MSK4DH12 of 2 models have all five ratings · AHRI 206724412
Ducted, 2.5–3 tons	No models in this size class	29.0(50 is the typical model of its size class)V5BV-28WMAK1 of 1 models have all five ratings · AHRI 205767448
Ducted, 3.5–4.5 tons	No models in this size class	63.3(50 is the typical model of its size class)GXH48-60MSK4DHwith ducted air handler GMH48-**MSK4DH11 of 1 models have all five ratings · AHRI 206724414
Non-ducted, up to 1.5 tons	58.1(50 is the typical model of its size class)GFMCX18-H23 of 3 models have all five ratings · AHRI 212925599	No models in this size class
Non-ducted, 2 tons	71.5(50 is the typical model of its size class) (higher)GFMCX24-H21 of 1 models have all five ratings · AHRI 212925602	19.8(50 is the typical model of its size class)V5BV-24WMAK1 of 1 models have all five ratings · AHRI 205767442
Non-ducted, 2.5–3 tons	No models in this size class	21.4(50 is the typical model of its size class)V5BV-28WMAK1 of 1 models have all five ratings · AHRI 205767445

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
Rating	COMFORMATIC	MAMMOTH
COP at 5°F	beats 90% · 2.22GFMCX18-H2Non-ducted, up to 1.5 tons	beats 26% · 1.80V5BV-24WMAKNon-ducted, 2 tons
Capacity retention at 5°F	beats 75% · 96%GFMCX24-H2Ducted, 2 tons	beats 73% · 81%GXH48-60MSK4DHDucted, 3.5–4.5 tons
HSPF2	beats 73% · 10.0GFMCX24-H2Non-ducted, 2 tons	beats 73% · 9.0GXH48-60MSK4DHDucted, 3.5–4.5 tons
SEER2	beats 66% · 21.0GFMCX24-H2Non-ducted, 2 tons	beats 77% · 17.0GXH48-60MSK4DHDucted, 3.5–4.5 tons
EER2	beats 62% · 12.5GFMCX24-H2Non-ducted, 2 tons	beats 66% · 12.0GXH24-36MSK4DHDucted, 2 tons
Heating capacity at 5°F	beats 84% · 13,800 Btu/hGFMCX18-H2Non-ducted, up to 1.5 tons	beats 74% · 41,000 Btu/hGXH48-60MSK4DHDucted, 3.5–4.5 tons

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