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.

Della 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, Della scores higher on 6 of the 6 ratings.

Della
THERMAL ZONE
Other ranked manufacturers

Source: AHRI Directory, NEEP · as of Oct 9, 2026

Average peer percentile, raw median and rank among ranked manufacturers
Rating	Della	THERMAL ZONE
Efficiency index	48% (higher)median — · 24th ranked	30% (higher)median —
COP at 5°F	43% (higher)median 1.93 · 26th ranked	40% (higher)median 1.86
Capacity retention at 5°F	44% (higher)median 73% · 21st ranked	26% (higher)median 46%
HSPF2	50% (higher)median 9.5 · 16th ranked	23% (higher)median 7.2
SEER2	55% (higher)median 21.0 · 14th ranked	24% (higher)median 14.3
EER2	41% (higher)median 11.2 · 23rd ranked	31% (higher)median 10.6
Heating capacity at 5°F	46% (higher)median 12,250 Btu/h · 21st ranked	29% (higher)median 18,550 Btu/h
Outdoor models	94	101
AHRI certifications	133	1,006

Share of models meeting each standard

Percent of each manufacturer’s models with a qualifying certification
Standard	Della	THERMAL ZONE
CEE 2025 Tier 1 (Split ASHP)	68.1%64 models	7.9%8 models
CEE 2026 Tier 1 (Split ASHP)	68.1%64 models	5.9%6 models
CEE Advanced Tier (Split ASHP)	0%0 models	0%0 models
Xcel Energy Colorado cold-climate ASHP (2025)	66%62 models	7.9%8 models
DOE Cold Climate Heat Pump Challenge	0%0 models	0%0 models
ENERGY STAR Cold Climate	43.6%41 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 · 4 groups where both have models

Della
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 9, 2026

Models per peer group · efficiency index within the group
Size and duct type	Della	THERMAL ZONE
Ducted, up to 1.5 tons	3 · index 67%	5 · index 34%
Ducted, 2 tons	2 · index 46%	11 · index 33%
Ducted, 2.5–3 tons	6 · index 65%	30 · index 26%
Ducted, 3.5–4.5 tons	6 · index 54%	38 · index 31%
Ducted, 5 tons and up	None	17 · index 28%
Non-ducted, up to 1.5 tons	60 · index 46%	None
Non-ducted, 2 tons	13 · index 45%	None
Non-ducted, 2.5–3 tons	12 · index 42%	None
Non-ducted, 3.5–4.5 tons	5 · index 44%	None

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	DellaCold-climate score, best model	THERMAL ZONECold-climate score, best model
Ducted, up to 1.5 tons	57.7(50 is the typical model of its size class)048-TLP-MODU-1D23 of 3 models qualify · AHRI 217568631	72.0(50 is the typical model of its size class) (higher)TZP15AY18AJ2Nwith ducted air handler PE(S,T)23J1 of 5 models qualify · AHRI 217200657
Ducted, 2 tons	56.4(50 is the typical model of its size class)048-TCQ-MODU-1D32 of 2 models qualify · AHRI 218718736	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	63.1(50 is the typical model of its size class)048-TPH-MODU-1D46 of 6 models qualify · AHRI 218718740	72.6(50 is the typical model of its size class) (higher)TZP15AY36AJ2Nwith ducted air handler AEW37J+TDR2 of 30 models qualify · AHRI 217200653
Ducted, 3.5–4.5 tons	63.6(50 is the typical model of its size class)048-TCQ-MODU-1D56 of 6 models qualify · AHRI 218718738	65.9(50 is the typical model of its size class) (higher)TZID48H520ZCSwith indoor coil TZID60H520ZACD and furnace MGV96U120D5C3 of 38 models qualify · AHRI 218782171
Ducted, 5 tons and up	No models in this size class	None on this board (0 of 17 models qualify)
Non-ducted, up to 1.5 tons	70.9(50 is the typical model of its size class)048-TPH-MODU-1D342 of 60 models qualify · AHRI 218471007	No models in this size class
Non-ducted, 2 tons	77.5(50 is the typical model of its size class)048-MS-24K2VR-22S-MX-OUTwith ductless indoor unit 048-MS-24K2VR-22S-MX-IN6 of 13 models qualify · AHRI 218043770	No models in this size class
Non-ducted, 2.5–3 tons	68.0(50 is the typical model of its size class)048-TPH-MODU-1D48 of 12 models qualify · AHRI 218471008	No models in this size class
Non-ducted, 3.5–4.5 tons	48.1(50 is the typical model of its size class)048-TPH-MODU-1D64 of 5 models qualify · AHRI 218471010	No models in this size class

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	DellaAll-around score, best model	THERMAL ZONEAll-around score, best model
Ducted, up to 1.5 tons	72.9(50 is the typical model of its size class) (higher)048-TPH-MODU-1D33 of 3 models have all five ratings · AHRI 218718739	57.9(50 is the typical model of its size class)TZP15AY18AJ2Nwith ducted air handler L(E,F)W30BJ4 of 4 models have all five ratings · AHRI 217200644
Ducted, 2 tons	54.0(50 is the typical model of its size class)048-TCQ-MODU-1D32 of 2 models have all five ratings · AHRI 218718736	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	79.9(50 is the typical model of its size class) (higher)048-TPH-MODU-1D46 of 6 models have all five ratings · AHRI 218718740	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	67.5(50 is the typical model of its size class) (higher)048-TLP-MODU-1D56 of 6 models have all five ratings · AHRI 217568634	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	No models in this size class	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
Non-ducted, up to 1.5 tons	82.6(50 is the typical model of its size class)048-TPH-MODU-1D355 of 60 models have all five ratings · AHRI 218471007	No models in this size class
Non-ducted, 2 tons	68.1(50 is the typical model of its size class)048-MS-24K2VR-22S-MX-OUTwith ductless indoor unit 048-MS-24K2VR-22S-MX-IN12 of 13 models have all five ratings · AHRI 218043770	No models in this size class
Non-ducted, 2.5–3 tons	83.1(50 is the typical model of its size class)048-TPH-MODU-1D412 of 12 models have all five ratings · AHRI 218471008	No models in this size class
Non-ducted, 3.5–4.5 tons	70.2(50 is the typical model of its size class)048-TPH-MODU-1D65 of 5 models have all five ratings · AHRI 218471010	No models in this size class

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	Della	THERMAL ZONE
COP at 5°F	beats 89% · 2.27048-MS-24K2VR-21S-OUTNon-ducted, 2 tons	beats 99% · 2.73TZP15AY18AJ2NDucted, up to 1.5 tons
Capacity retention at 5°F	beats 95% · 105%048-TPH-MODU-1D3Ducted, up to 1.5 tons	beats 100% · 130%TZP15AY18AJ2NDucted, up to 1.5 tons
HSPF2	beats 96% · 10.5048-TPH-MODU-1D4Ducted, 2.5–3 tons	beats 74% · 9.7TZID24H520ZCSDucted, 2 tons
SEER2	beats 99% · 26.5048-TPH-MODU-1D4Non-ducted, 2.5–3 tons	beats 87% · 20.0TZID36H520ZCDucted, 2 tons
EER2	beats 97% · 14.0048-TPH-MODU-1D4Non-ducted, 2.5–3 tons	beats 93% · 13.3TZID36H520ZCDucted, 2 tons
Heating capacity at 5°F	beats 98% · 19,800 Btu/h048-TPH-MODU-1D3Non-ducted, up to 1.5 tons	beats 99% · 21,000 Btu/hTZP15AY18AJ2NDucted, up to 1.5 tons

More comparisons

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Della vs THERMAL ZONE heat pumps