RUSSELL vs THERMAL ZONE heat pumps

Measured against models of the same size and duct type, RUSSELL and THERMAL ZONE split the 6 ratings 3–3. RUSSELL has 111 outdoor models, THERMAL ZONE has 101 outdoor models. RUSSELL and THERMAL ZONE 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.

RUSSELL and THERMAL ZONE 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, RUSSELL and THERMAL ZONE split the 6 ratings 3–3.

RUSSELL
THERMAL ZONE
Other ranked manufacturers

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

Average peer percentile, raw median and rank among ranked manufacturers
Rating	RUSSELL	THERMAL ZONE
Efficiency index	33% (higher)median —	30% (higher)median —
COP at 5°F	37%median 1.82	40%median 1.86
Capacity retention at 5°F	21%median 45%	26%median 46%
HSPF2	24% (higher)median 7.2	23% (higher)median 7.2
SEER2	28% (higher)median 14.3	24% (higher)median 14.3
EER2	36% (higher)median 10.6	31% (higher)median 10.6
Heating capacity at 5°F	21%median 18,000 Btu/h	29%median 18,550 Btu/h
Outdoor models	111	101
AHRI certifications	2,007	1,006

Share of models meeting each standard

Percent of each manufacturer’s models with a qualifying certification
Standard	RUSSELL	THERMAL ZONE
CEE 2025 Tier 1 (Split ASHP)	10.8%12 models	7.9%8 models
CEE 2026 Tier 1 (Split ASHP)	9%10 models	5.9%6 models
CEE Advanced Tier (Split ASHP)	0%0 models	0%0 models
Xcel Energy Colorado cold-climate ASHP (2025)	7.2%8 models	7.9%8 models
DOE Cold Climate Heat Pump Challenge	0%0 models	0%0 models
ENERGY STAR Cold Climate	11.7%13 models	7.9%8 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 · 5 groups where both have models

RUSSELL
THERMAL ZONE
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	RUSSELL	THERMAL ZONE
Ducted, up to 1.5 tons	2 · index 27%	5 · index 34%
Ducted, 2 tons	12 · index 29%	11 · index 33%
Ducted, 2.5–3 tons	33 · index 31%	30 · index 26%
Ducted, 3.5–4.5 tons	44 · index 36%	38 · index 31%
Ducted, 5 tons and up	20 · index 33%	17 · index 28%

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	RUSSELLCold-climate score, best model	THERMAL ZONECold-climate score, best model
Ducted, up to 1.5 tons	None on this board (0 of 2 models qualify)	72.0(50 is the typical model of its size class)TZP15AY18AJ2Nwith ducted air handler PE(S,T)23J1 of 5 models qualify · AHRI 217200657
Ducted, 2 tons	70.3(50 is the typical model of its size class)RD18AY24AJVCwith indoor coil TCFY2417STANM and furnace S962V0603A17M42 of 12 models qualify · AHRI 217906632	75.5(50 is the typical model of its size class) (higher)TZP15AY24AJ2Nwith ducted air handler L(E,F)W30BJ4 of 11 models qualify · AHRI 217200648
Ducted, 2.5–3 tons	78.1(50 is the typical model of its size class) (higher)RD18AY36AJVCwith indoor coil TCFY3621MTANM and furnace S801V0504A17UHS2 of 33 models qualify · AHRI 216892076	72.6(50 is the typical model of its size class)TZP15AY36AJ2Nwith ducted air handler AEW37J+TDR2 of 30 models qualify · AHRI 217200653
Ducted, 3.5–4.5 tons	80.9(50 is the typical model of its size class) (higher)SP19AY48AJVCwith indoor coil TCFY4821SEAAM and furnace S802V0754A17DZ4 of 44 models qualify · AHRI 216051255	65.9(50 is the typical model of its size class)TZID48H520ZCSwith indoor coil TZID60H520ZACD and furnace MGV96U120D5C3 of 38 models qualify · AHRI 218782171
Ducted, 5 tons and up	None on this board (0 of 20 models qualify)	None on this board (0 of 17 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	RUSSELLAll-around score, best model	THERMAL ZONEAll-around score, best model
Ducted, up to 1.5 tons	38.2(50 is the typical model of its size class)SP15AY18AJ2Nwith ducted air handler RF2TY2421STANS2 of 2 models have all five ratings · AHRI 216533447	57.9(50 is the typical model of its size class) (higher)TZP15AY18AJ2Nwith ducted air handler L(E,F)W30BJ4 of 4 models have all five ratings · AHRI 217200644
Ducted, 2 tons	74.3(50 is the typical model of its size class)SP19AY24AJVCwith indoor coil TCFY2421HEAAM and furnace S972V0603A17UPS12 of 12 models have all five ratings · AHRI 218728661	79.6(50 is the typical model of its size class) (higher)TZID36H520ZCwith ducted air handler TZID24H520ZA12 of 12 models have all five ratings · AHRI 217495954
Ducted, 2.5–3 tons	84.1(50 is the typical model of its size class) (higher)RD18AY36AJVCwith ducted air handler SH2VY3621MTACN19 of 33 models have all five ratings · AHRI 217166015	58.7(50 is the typical model of its size class)TZP15AY36AJ2Nwith ducted air handler AEW37J+TDR16 of 29 models have all five ratings · AHRI 217200653
Ducted, 3.5–4.5 tons	84.1(50 is the typical model of its size class) (higher)SP19AY48AJVCwith indoor coil TCFY4821SEAAM and furnace S802V0754A17UH23 of 43 models have all five ratings · AHRI 216051262	64.4(50 is the typical model of its size class)TZID60H520ZCwith ducted air handler TZID48H520ZA19 of 37 models have all five ratings · AHRI 217589556
Ducted, 5 tons and up	56.6(50 is the typical model of its size class)SP15AY60AJ2Nwith ducted air handler SH2CY6024STANN11 of 21 models have all five ratings · AHRI 215415481	56.6(50 is the typical model of its size class)TZP15AY60AJ2Nwith ducted air handler TZHDYTST6024*NAN9 of 19 models have all five ratings · AHRI 215415492

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	RUSSELL	THERMAL ZONE
COP at 5°F	beats 91% · 2.40RD16AY36AJVCDucted, 2.5–3 tons	beats 99% · 2.73TZP15AY18AJ2NDucted, up to 1.5 tons
Capacity retention at 5°F	beats 88% · 97%SP19AY60AJVCDucted, 3.5–4.5 tons	beats 100% · 130%TZP15AY18AJ2NDucted, up to 1.5 tons
HSPF2	beats 86% · 10.0SP19AY48AJVCDucted, 3.5–4.5 tons	beats 74% · 9.7TZID24H520ZCSDucted, 2 tons
SEER2	beats 98% · 21.0SP19AY36AJVCDucted, 2.5–3 tons	beats 87% · 20.0TZID36H520ZCDucted, 2 tons
EER2	beats 96% · 13.0RD18AY36AJVCDucted, 2.5–3 tons	beats 93% · 13.3TZID36H520ZCDucted, 2 tons
Heating capacity at 5°F	beats 95% · 53,000 Btu/hSP19AY60AJVCDucted, 3.5–4.5 tons	beats 99% · 21,000 Btu/hTZP15AY18AJ2NDucted, up to 1.5 tons

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