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SLIMAIR vs Viessmann heat pumps

Measured against models of the same size and duct type, SLIMAIR scores higher on 5 of the 6 ratings. SLIMAIR has 54 outdoor models, Viessmann has 53 outdoor models. SLIMAIR and Viessmann 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.
SLIMAIR and Viessmann 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, SLIMAIR scores higher on 5 of the 6 ratings.
  • SLIMAIR
  • Viessmann
  • Other ranked manufacturers
SLIMAIRViessmann

Source: AHRI Directory, NEEP · as of

Average peer percentile, raw median and rank among ranked manufacturers
RatingSLIMAIRViessmann
Efficiency index59% (higher)median —53% (higher)median —
COP at 5°F47%median 1.9152%median 1.95
Capacity retention at 5°F58% (higher)median 73%50% (higher)median 67%
HSPF271% (higher)median 9.563% (higher)median 9.2
SEER265% (higher)median 19.858% (higher)median 18.7
EER249% (higher)median 11.046% (higher)median 10.7
Heating capacity at 5°F57% (higher)median 20,000 Btu/h50% (higher)median 18,000 Btu/h
Outdoor models5453
AHRI certifications100123

Share of models meeting each standard

Percent of each manufacturer’s models with a qualifying certification
StandardSLIMAIRViessmann
CEE 2025 Tier 1 (Split ASHP)66.7%36 models64.2%34 models
CEE 2026 Tier 1 (Split ASHP)59.3%32 models60.4%32 models
CEE Advanced Tier (Split ASHP)1.9%1 models3.8%2 models
Xcel Energy Colorado cold-climate ASHP (2025)50%27 models43.4%23 models
DOE Cold Climate Heat Pump Challenge1.9%1 models3.8%2 models
ENERGY STAR Cold Climate42.6%23 models47.2%25 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 · 9 groups where both have models
  • SLIMAIR
  • Viessmann
  • 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 modelsDucted, 5 tons and up1.90239 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 typeSLIMAIRViessmann
Ducted, up to 1.5 tons10 · index 63%6 · index 61%
Ducted, 2 tons4 · index 70%4 · index 65%
Ducted, 2.5–3 tons11 · index 56%9 · index 55%
Ducted, 3.5–4.5 tons11 · index 57%6 · index 59%
Ducted, 5 tons and up2 · index 49%2 · index 49%
Non-ducted, up to 1.5 tons18 · index 62%20 · index 53%
Non-ducted, 2 tons4 · index 58%4 · index 47%
Non-ducted, 2.5–3 tons8 · index 54%11 · index 47%
Non-ducted, 3.5–4.5 tons4 · index 51%5 · index 46%

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 typeSLIMAIRCold-climate score, best modelViessmannCold-climate score, best model
Ducted, up to 1.5 tons74.9(50 is the typical model of its size class)SHC09VH2AGwith ducted air handler SHD09VC2AG8 of 10 models qualify · AHRI 21460646381.3(50 is the typical model of its size class) (higher)DLCSRBH18AAKwith ducted air handler DLFSDAH18XHK5 of 6 models qualify · AHRI 215569862
Ducted, 2 tons80.3(50 is the typical model of its size class) (higher)SHC24VE2AGwith ducted air handler SHD24VC2AG4 of 4 models qualify · AHRI 21460645979.4(50 is the typical model of its size class)DLCSRBH24AAKwith ducted air handler DLFSDAH24XAK4 of 4 models qualify · AHRI 215569794
Ducted, 2.5–3 tons79.9(50 is the typical model of its size class) (higher)SHC36VH2AGwith ducted air handler SHD36VC2AG6 of 11 models qualify · AHRI 21460646778.6(50 is the typical model of its size class)DLCURAH36ABKwith ducted air handler DLFULAH36XCX + CI3 of 9 models qualify · AHRI 215569769
Ducted, 3.5–4.5 tons86.4(50 is the typical model of its size class) (higher)SHC48VH2AGwith ducted air handler SHD48VC2AG6 of 11 models qualify · AHRI 21460646874.9(50 is the typical model of its size class)DLCMHBH48EAK4 of 6 models qualify · AHRI 215569823
Ducted, 5 tons and upNone on this board (0 of 2 models qualify)None on this board (0 of 2 models qualify)
Non-ducted, up to 1.5 tons86.0(50 is the typical model of its size class)SHC09VE2AGwith ductless indoor unit SHM09VE2AG12 of 18 models qualify · AHRI 20844793695.0(50 is the typical model of its size class) (higher)DLCPRBH18AAKwith ductless indoor unit DLFPHBH18XAK11 of 20 models qualify · AHRI 215569835
Non-ducted, 2 tons86.1(50 is the typical model of its size class)SHC24VH2AGwith ductless indoor unit SHLZ24VC2AG3 of 4 models qualify · AHRI 21472830386.1(50 is the typical model of its size class)DLCSRBH24AAKwith ductless indoor unit DLFSCBH24XAK2 of 4 models qualify · AHRI 215569833
Non-ducted, 2.5–3 tons73.4(50 is the typical model of its size class)SHC4Z36VE2AG4 of 8 models qualify · AHRI 21388604473.4(50 is the typical model of its size class)DLCMHBH36DAK2 of 11 models qualify · AHRI 215569824
Non-ducted, 3.5–4.5 tons80.5(50 is the typical model of its size class)SHC5Z48VE2AG2 of 4 models qualify · AHRI 21388604780.5(50 is the typical model of its size class)DLCMHBH48EAK3 of 5 models qualify · AHRI 215569822

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 typeSLIMAIRAll-around score, best modelViessmannAll-around score, best model
Ducted, up to 1.5 tons85.2(50 is the typical model of its size class)SHC09VH2AGwith ducted air handler SHD09VC2AG10 of 10 models have all five ratings · AHRI 21460646385.2(50 is the typical model of its size class)DLCSRBH09AAKwith ducted air handler DLFSDAH09XAK6 of 6 models have all five ratings · AHRI 215569786
Ducted, 2 tons83.8(50 is the typical model of its size class) (higher)SHC24VE2AGwith ducted air handler SHD24VC2AG4 of 4 models have all five ratings · AHRI 21460645980.1(50 is the typical model of its size class)DLCSRBH24AAKwith ducted air handler DLFSDAH24XAK4 of 4 models have all five ratings · AHRI 215569794
Ducted, 2.5–3 tons74.6(50 is the typical model of its size class) (higher)SHC3Z27VE2AG10 of 11 models have all five ratings · AHRI 21388604272.0(50 is the typical model of its size class)DLCMHBH30DAK9 of 9 models have all five ratings · AHRI 215569818
Ducted, 3.5–4.5 tons82.0(50 is the typical model of its size class)SHC5Z48VE2AG10 of 11 models have all five ratings · AHRI 21388604882.0(50 is the typical model of its size class)DLCMHBH48EAK6 of 6 models have all five ratings · AHRI 215569823
Ducted, 5 tons and up57.1(50 is the typical model of its size class)SHC60VC2AGwith ducted air handler SHD60VC2AG2 of 2 models have all five ratings · AHRI 21460646257.1(50 is the typical model of its size class)DLCLRCH58AAKwith ducted air handler DLFLDAH58XAK2 of 2 models have all five ratings · AHRI 215569836
Non-ducted, up to 1.5 tons86.7(50 is the typical model of its size class)SHC09VE2AGwith ductless indoor unit SHM09VE2AG18 of 18 models have all five ratings · AHRI 20844793693.6(50 is the typical model of its size class) (higher)DLCPRBH18AAKwith ductless indoor unit DLFPHBH18XAK20 of 20 models have all five ratings · AHRI 215569835
Non-ducted, 2 tons70.7(50 is the typical model of its size class)SHCD24VC2AGwith ductless indoor unit SHMZ24VC2AGAlso listed as SHC24VH2AG4 of 4 models have all five ratings · AHRI 20844794384.3(50 is the typical model of its size class) (higher)DLCSRBH24AAKwith ductless indoor unit DLFSHCH24XAK4 of 4 models have all five ratings · AHRI 215569840
Non-ducted, 2.5–3 tons70.8(50 is the typical model of its size class)SHC4Z36VE2AG7 of 8 models have all five ratings · AHRI 21388604470.8(50 is the typical model of its size class)DLCMHBH36DAK11 of 11 models have all five ratings · AHRI 215569824
Non-ducted, 3.5–4.5 tons73.8(50 is the typical model of its size class)SHC5Z48VE2AG4 of 4 models have all five ratings · AHRI 21388604773.8(50 is the typical model of its size class)DLCMHBH48EAK5 of 5 models have all five ratings · AHRI 215569822

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
RatingSLIMAIRViessmann
COP at 5°Fbeats 96% · 2.22SHC24VE2AGNon-ducted, 2 tonsbeats 99% · 2.89DLCPRBH18AAKNon-ducted, up to 1.5 tons
Capacity retention at 5°Fbeats 95% · 113%SHC09VE2AGNon-ducted, up to 1.5 tonsbeats 97% · 120%DLCPRBH18AAKNon-ducted, up to 1.5 tons
HSPF2beats 99% · 10.3SHC48VH2AGDucted, 3.5–4.5 tonsbeats 100% · 15.0DLCPRBH09AAKNon-ducted, up to 1.5 tons
SEER2beats 99% · 20.9SHC5Z48VE2AGDucted, 3.5–4.5 tonsbeats 99% · 20.9DLCMHBH48EAKDucted, 3.5–4.5 tons
EER2beats 95% · 15.8SHCD09VC2AGAlso listed as SHC09VH2AGNon-ducted, up to 1.5 tonsbeats 98% · 16.2DLCSRBH09AAKNon-ducted, up to 1.5 tons
Heating capacity at 5°Fbeats 98% · 53,000 Btu/hSHC55VH2AGDucted, 3.5–4.5 tonsbeats 100% · 24,000 Btu/hDLCPRBH18AAKNon-ducted, up to 1.5 tons

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