RUSSELL vs THERMAL ZONE heat pumps

Measured against models of the same size and duct type, RUSSELL scores higher on 5 of the 6 ratings. RUSSELL has 60 outdoor models, THERMAL ZONE has 88 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 scores higher on 5 of the 6 ratings.

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	49% (higher)median —	43% (higher)median —
COP at 5°F	80% (higher)median 2.20	68% (higher)median 2.10
Capacity retention at 5°F	43% (higher)median 57%	37% (higher)median 56%
HSPF2	25%median 7.2	31%median 7.5
SEER2	32% (higher)median 14.3	26% (higher)median 14.3
EER2	42% (higher)median 10.6	36% (higher)median 10.6
Heating capacity at 5°F	42% (higher)median 24,200 Btu/h	40% (higher)median 19,900 Btu/h
Outdoor models	60	88
AHRI certifications	1,231	509

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)	16.7%10 models	12.5%11 models
CEE 2026 Tier 1 (Split ASHP)	16.7%10 models	11.4%10 models
CEE Advanced Tier (Split ASHP)	3.3%2 models	0%0 models
Xcel Energy Colorado cold-climate ASHP (2025)	13.3%8 models	6.8%6 models
DOE Cold Climate Heat Pump Challenge	3.3%2 models	0%0 models
ENERGY STAR Cold Climate	21.7%13 models	21.6%19 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%	8 · index 32%
Ducted, 2 tons	7 · index 52%	9 · index 42%
Ducted, 2.5–3 tons	17 · index 52%	27 · index 44%
Ducted, 3.5–4.5 tons	26 · index 50%	31 · index 46%
Ducted, 5 tons and up	8 · index 70%	12 · index 55%
Non-ducted, 2.5–3 tons	None	1 · index —

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)	67.7(50 is the typical model of its size class)TZPLV182PAwith ducted air handler H,RG21924+TD1 of 8 models qualify · AHRI 214311494
Ducted, 2 tons	74.7(50 is the typical model of its size class) (higher)SP18AZ24AJVCwith indoor coil TCFZ2421HEAAM and furnace S951V0403A17UHU2 of 7 models qualify · AHRI 213372369	66.5(50 is the typical model of its size class)TZPLV242PAwith ducted air handler TZHVLE2417JA2 of 9 models qualify · AHRI 211126503
Ducted, 2.5–3 tons	80.6(50 is the typical model of its size class) (higher)SP18AZ36AJVCwith ducted air handler SHMVZ6021SEACA2 of 17 models qualify · AHRI 210106900	78.6(50 is the typical model of its size class)TZPLV362PAwith ducted air handler MAC-36HWDN1-MN02 of 27 models qualify · AHRI 213885869
Ducted, 3.5–4.5 tons	76.3(50 is the typical model of its size class) (higher)SP18AZ48AJVCwith indoor coil TCFZ6021SEAAM and furnace S962V1005A21M4S4 of 26 models qualify · AHRI 210106968	73.8(50 is the typical model of its size class)TZPLV482PAwith ducted air handler TZHVLE4821JA2 of 31 models qualify · AHRI 211126512
Ducted, 5 tons and up	None on this board (0 of 8 models qualify)	None on this board (0 of 12 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	RUSSELLAll-around score, best model	THERMAL ZONEAll-around score, best model
Ducted, up to 1.5 tons	34.5(50 is the typical model of its size class)SP15AZ18AJ2Nwith ducted air handler SH2CZ2417STANN2 of 2 models have all five ratings · AHRI 211627516	63.4(50 is the typical model of its size class) (higher)TZPLV182PAwith ducted air handler TZHVLE1817JA6 of 8 models have all five ratings · AHRI 211126509
Ducted, 2 tons	83.6(50 is the typical model of its size class) (higher)SP18AZ24AJVCwith indoor coil TCFZ2421HEAAM and furnace S951V0403A17UHU4 of 7 models have all five ratings · AHRI 213372369	65.8(50 is the typical model of its size class)TZPLV242PAwith ducted air handler TZHVLE2417JA6 of 9 models have all five ratings · AHRI 211126503
Ducted, 2.5–3 tons	87.2(50 is the typical model of its size class) (higher)SP18AZ36AJVCwith indoor coil TCFZ6021SEAAM and furnace S802VA100521Z6 of 17 models have all five ratings · AHRI 210589394	58.0(50 is the typical model of its size class)TZPLAD1530AJNwith ducted air handler TZHDLVST3617*NAN10 of 27 models have all five ratings · AHRI 212508013
Ducted, 3.5–4.5 tons	80.3(50 is the typical model of its size class) (higher)SP18AZ48AJVCwith indoor coil TCFZ6021SEAAM and furnace S802VA100521Z9 of 26 models have all five ratings · AHRI 210589350	62.1(50 is the typical model of its size class)TZPLAD1548AJNwith ducted air handler TZHDLVST4821*NAN10 of 30 models have all five ratings · AHRI 212508016
Ducted, 5 tons and up	70.2(50 is the typical model of its size class) (higher)SP15AZ60AJ2Nwith indoor coil TCFZ6024STANM and furnace S97MV1005A21DHS1 of 8 models have all five ratings · AHRI 212387320	67.6(50 is the typical model of its size class)TZP15AZ60AJ2Nwith ducted air handler TZHDLTST6024*NANAlso listed as TZPLAD1560AJN3 of 13 models have all five ratings · AHRI 211641701
Non-ducted, 2.5–3 tons	No models in this size class	None on this board (0 of 1 models have all five ratings)

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 98% · 2.60SP15AZ60AJ2NDucted, 5 tons and up	beats 90% · 2.50TZPLAD1560AJNDucted, 3.5–4.5 tons
Capacity retention at 5°F	beats 100% · 105%SP18AZ48AJVCDucted, 3.5–4.5 tons	beats 97% · 102%TZPLV362PADucted, 2.5–3 tons
HSPF2	beats 75% · 9.5RD17AZ24AJ3NDucted, 2 tons	beats 93% · 10.0TZPLV362PADucted, 2.5–3 tons
SEER2	beats 94% · 20.0SP18AZ24AJVCDucted, 2 tons	beats 70% · 16.0TZP15AZ60AJ2NAlso listed as TZPLAD1560AJNDucted, 5 tons and up
EER2	beats 91% · 12.5SP18AZ36AJVCDucted, 2.5–3 tons	beats 78% · 11.7TZP15AZ60AJ2NAlso listed as TZPLAD1560AJNDucted, 5 tons and up
Heating capacity at 5°F	beats 100% · 43,500 Btu/hSP18AZ36AJVCDucted, 2.5–3 tons	beats 95% · 48,500 Btu/hTZPLV602PADucted, 3.5–4.5 tons

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