What is the SEER2 rating of the Heil H5H6S18*K*AAA?

The Heil H5H6S18*K*AAA is rated at up to 15.5 SEER2 and 12.5 EER2 for cooling and up to 8.0 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with; across its 138 certified matchups SEER2 ranges from 15.2-15.5.

Is the Heil H5H6S18*K*AAA good for cold climates?

It is not cold-climate certified: none of its matchups meet the ENERGY STAR cold-climate criteria (a COP of at least 1.75 at 5°F among other limits). In places with frequent sub-zero nights, pick a cold-climate 1.5-ton model.

How much does the Heil H5H6S18*K*AAA cost to run per year?

At its rated efficiency it costs about $548-$1,398 a year in electricity in large U.S. cities, depending on climate and local rates - for example $666 in Phoenix and $1,161 in Minneapolis. The calculator on this page works it out for your city and compares it with your current system.

Is the Heil H5H6S18*K*AAA the same as the Day & Night C5H6S18*K*AAA?

Yes, as far as the certified ratings go. ENERGY STAR lists both model numbers with identical efficiency, capacity and matchups, which means the same outdoor unit sold under a different brand or with a minor variant code (voltage, colour or region). The full list is on this page.

Which indoor units work with the Heil H5H6S18*K*AAA?

ENERGY STAR lists 138 certified combinations for this outdoor unit. The highest-rated ones use FMA5X24**AL, EVM5X32M17A, FM(C,U)5Z18**AL.

1.5-ton central heat pump · MAINLINE 16 SEER2 HP

Heil H5H6S18KAAA

Below average cooling and heating efficiency for a 1.5-ton central heat pump, but not rated for cold climates.

Ranks #144 of 170 1.5 ton central heat pumps for cooling efficiency, and costs about $591 a year to run in a mixed climate like Atlanta.

SEER2: 15.5 Cooling efficiency over a season
Below average · beats 15%
HSPF2: 8.0 Heating efficiency over a season
Below average · beats 12%
EER2: 12.5 Cooling efficiency on a 95°F day
Very good · beats 80%
Heat at 5°F: 8,500 BTU/h46% of its 47°F output
Average · beats 58%

A good fit if…

You want a choice of indoor units - 138 certified pairings.

Think twice if…

You often see nights below 0°F - it is not cold-climate certified.
Cooling cost matters most - its SEER2 is below average for central heat pumps.
You mainly need heat - its HSPF2 is below average for central heat pumps.
Comfort and noise matter - a single-stage compressor runs only full-on or off.

Calculate my running cost

Details

Specifications1.5 ton, R-454B

General
Brand	Heil
Also sold as	Airquest, Arcoaire, Day & Night, Keeprite, Comfortmaker
Outdoor unit model	H5H6S18KAAA
Series	MAINLINE 16 SEER2 HP
Type	Central heat pump
Nominal size	1.5 ton
CompressorVariable-speed units run longer at low power	Single stage
Refrigerant	R-454B
Connected (smart) capable	No
On the market since	July 1, 2022
Last certified	July 16, 2026
Cooling
SEER2Seasonal efficiency, higher is better	15.5 (range 15.2-15.5)
EER2Efficiency at 95°F outdoors	11.7-12.5
Cooling capacity	17,400-18,900 BTU/h
Heating
HSPF2Seasonal efficiency, higher is better	7.8-8.0
Capacity at 47°F	16,400-18,100 BTU/h
Capacity at 17°F	10,500-10,900 BTU/h
Capacity at 5°F	8,200-8,500 BTU/h
COP at 5°F2.0 = twice as efficient as a space heater	1.94-2.10
ENERGY STAR cold climate	No

Heating output as it gets colder46% kept at 5°F

Every heat pump delivers less heat as the outdoor temperature drops. Certified output of its matchup with FMA5X24**AL at the standard test temperatures, in BTU/h:

Certified matchups138 indoor units

The same outdoor unit scores differently with each indoor unit and furnace. The 60 highest-rated of 138 are shown. Ask your installer for the AHRI reference number of the exact system you are quoted.

Indoor unit	Furnace	SEER2	EER2	HSPF2	Heat @5°F	AHRI ref.
FMA5X24**AL	-	15.5	12.5	8.0	8,200	214423963
FMA5X24**AL	-	15.5	12.5	8.0	8,200	214423964
FMA5X24**AL	-	15.5	12.5	8.0	8,200	214423965
EVM5X32M17A	80MS(N,L)0701712A	15.5	12.0	7.8	8,200	214156823
EVM5X32M17A	80MS(N,L)0701712A	15.5	12.0	7.8	8,200	214156824
EVM5X32M17A	80MS(N,L)0701712A	15.5	12.0	7.8	8,200	214156825
EVM5X32M17A	80MS(N,L)0701716A	15.5	12.0	7.8	8,200	214156831
EVM5X32M17A	80MS(N,L)0701716A	15.5	12.0	7.8	8,200	214156833
EVM5X32M17A	80MS(N,L)0701716A	15.5	12.0	7.8	8,200	214156832
FM(C,U)5Z18**AL	-	15.2	12.0	8.0	8,500	215828871
FM(C,U)5Z18**AL	-	15.2	12.0	8.0	8,500	215828872
FM(C,U)5Z18**AL	-	15.2	12.0	8.0	8,500	215828873
FM(C,U)5Z24**AL	-	15.2	12.0	8.0	8,500	215828879
FM(C,U)5Z24**AL	-	15.2	12.0	8.0	8,500	215828880
FM(C,U)5Z24**AL	-	15.2	12.0	8.0	8,500	215828881
EA*5X25M17A	80VSL0451412B	15.2	12.0	7.8	8,400	214150711
EA*5X25M17A	80VSL0451412B	15.2	12.0	7.8	8,400	214150712
EA*5X25M17A	80VSL0451412B	15.2	12.0	7.8	8,400	214150713
EA*5X25M17A	80VSL0701716B	15.2	12.0	7.8	8,400	214150727
EA*5X25M17A	80VSL0701716B	15.2	12.0	7.8	8,400	214150728
EA*5X25M17A	80VSL0701716B	15.2	12.0	7.8	8,400	214150729
EA*5X25M17A	80ESU0401712A	15.2	12.0	7.8	8,400	214150743
EA*5X25M17A	80ESU0401712A	15.2	12.0	7.8	8,400	214150745
EA*5X25M17A	80ESU0401712A	15.2	12.0	7.8	8,400	214150744
EA*5X25M17A	80MSU0401712A	15.2	12.0	7.8	8,400	214150760
EA*5X25M17A	80MSU0401712A	15.2	12.0	7.8	8,400	214150759
EA*5X25M17A	80MSU0401712A	15.2	12.0	7.8	8,400	214150761
EA*5X25M17A	80MSU0601716A	15.2	12.0	7.8	8,400	214150767
EA*5X25M17A	80MSU0601716A	15.2	12.0	7.8	8,400	214150768
EA*5X25M17A	80MSU0601716A	15.2	12.0	7.8	8,400	214150769
EA*5X25M17A	80CTL0701412B	15.2	12.0	7.8	8,400	214150784
EA*5X25M17A	80CTL0701412B	15.2	12.0	7.8	8,400	214150785
EA*5X25M17A	80CTL0701412B	15.2	12.0	7.8	8,400	214150786
EA*5X25M17A	80CTL0701716B	15.2	12.0	7.8	8,500	214150792
EA*5X25M17A	80CTL0701716B	15.2	12.0	7.8	8,500	214150793
EA*5X25M17A	80CTL0701716B	15.2	12.0	7.8	8,500	214150794
EA*5X25M17A	80CTL0901716B	15.2	12.0	7.8	8,500	214150800
EA*5X25M17A	80CTL0901716B	15.2	12.0	7.8	8,500	214150801
EA*5X25M17A	80CTL0901716B	15.2	12.0	7.8	8,500	214150802
EA*5X25M17A	80VTL0451412B	15.2	12.0	7.8	8,400	214150816
EA*5X25M17A	80VTL0451412B	15.2	12.0	7.8	8,400	214150818
EA*5X25M17A	80VTL0451412B	15.2	12.0	7.8	8,400	214150817
EA*5X25M17A	80VTL0701716B	15.2	11.7	7.8	8,500	214150824
EA*5X25M17A	80VTL0701716B	15.2	11.7	7.8	8,500	214150826
EA*5X25M17A	80VTL0701716B	15.2	11.7	7.8	8,500	214150825
EA*5X25M17A	92MSN0601714A	15.2	12.0	7.8	8,400	214150896
EA*5X25M17A	92MSN0601714A	15.2	12.0	7.8	8,400	214150897
EA*5X25M17A	92MSN0601714A	15.2	12.0	7.8	8,400	214150898
EA*5X25M17A	92MSN0801716A	15.2	12.0	7.8	8,400	214150904
EA*5X25M17A	92MSN0801716A	15.2	12.0	7.8	8,400	214150905
EA*5X25M17A	92MSN0801716A	15.2	12.0	7.8	8,400	214150906
EA*5X25M17A	96MSN0801716A	15.2	11.7	7.8	8,500	214150920
EA*5X25M17A	96MSN0801716A	15.2	11.7	7.8	8,500	214150921
EA*5X25M17A	96MSN0801716A	15.2	11.7	7.8	8,500	214150922
EA*5X25M17A	95MSU0601716A	15.2	12.0	7.8	8,500	214150952
EA*5X25M17A	95MSU0601716A	15.2	12.0	7.8	8,500	214150953
EA*5X25M17A	95MSU0601716A	15.2	12.0	7.8	8,500	214150954
EA*5X25M17A	96CTN0801714B	15.2	12.0	7.8	8,400	214150968
EA*5X25M17A	96CTN0801714B	15.2	12.0	7.8	8,400	214150970
EA*5X25M17A	96CTN0801714B	15.2	12.0	7.8	8,400	214150969

Same unit, other model numbers1

These model numbers have exactly the same certified ratings and matchups as the Heil H5H6S18*K*AAA: the same equipment under another brand, or a variant code for voltage, colour or market. Everything on this page applies to them.

Day & Night C5H6S18*K*AAA

Yearly running cost in 10 large cities$548-$1,398

Phoenix, AZ$666/yr
Miami, FL$548/yr
Houston, TX$597/yr
Atlanta, GA$591/yr
Los Angeles, CA$573/yr
New York, NY$1,398/yr
Chicago, IL$1,132/yr
Denver, CO$939/yr
Seattle, WA$575/yr
Minneapolis, MN$1,161/yr

At each state's average electricity price and the city's typical heating and cooling hours.

Questions6

What is the SEER2 rating of the Heil H5H6S18*K*AAA?: The Heil H5H6S18*K*AAA is rated at up to 15.5 SEER2 and 12.5 EER2 for cooling and up to 8.0 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with; across its 138 certified matchups SEER2 ranges from 15.2-15.5.
Is the Heil H5H6S18*K*AAA good for cold climates?: It is not cold-climate certified: none of its matchups meet the ENERGY STAR cold-climate criteria (a COP of at least 1.75 at 5°F among other limits). In places with frequent sub-zero nights, pick a cold-climate 1.5-ton model.
How much does the Heil H5H6S18*K*AAA cost to run per year?: At its rated efficiency it costs about $548-$1,398 a year in electricity in large U.S. cities, depending on climate and local rates - for example $666 in Phoenix and $1,161 in Minneapolis. The calculator on this page works it out for your city and compares it with your current system.
Is the Heil H5H6S18*K*AAA the same as the Day & Night C5H6S18*K*AAA?: Yes, as far as the certified ratings go. ENERGY STAR lists both model numbers with identical efficiency, capacity and matchups, which means the same outdoor unit sold under a different brand or with a minor variant code (voltage, colour or region). The full list is on this page.
Which indoor units work with the Heil H5H6S18*K*AAA?: ENERGY STAR lists 138 certified combinations for this outdoor unit. The highest-rated ones use FMA5X24**AL, EVM5X32M17A, FM(C,U)5Z18**AL.
What refrigerant does the Heil H5H6S18*K*AAA use?: It uses R-454B.

Running cost and savings

Pre-filled with this model. Pick your city and what you heat with today; everything else is optional.

Heat pump $656/yrYou save $267/yrSee details ↓

1. Where you live

StateCityElectricity ¢ per kWh

Adjust heating and cooling hours

Filled in from your city's climate. Change them if you run the system much more or less than usual.

Cooling hours full-load hours per yearHeating hours full-load hours per year

2. The heat pump Heil H5H6S18*K*AAA

Find a model (fills in the ratings below)

SEER2 cooling efficiencyHSPF2 heating efficiencyCooling capacity BTU/hHeating capacity BTU/h

3. What it replaces

Current heatingFurnace efficiency (AFUE %)Gas price, $/thermCurrent coolingOld AC rating SEER2 (10 ≈ 15+ years old)

4. Price replace the example with your quote

Installed price, $Rebates and incentives, $ utility, state

Heat pump, per year: $656
Current system, per year: $923
You save per year: $267
Payback: 26.2 years
Net after 10 years: -$4,326

Cooling $411Heating $245Electricity used: 4,100 kWhSaved vs. a minimum-efficiency heat pump: $51

Estimates use the unit's rated SEER2 and HSPF2, full-load hours derived from NOAA 1991-2020 degree days, average residential electricity prices from the U.S. EIA (12 months to July 2026) and fuel prices from EIA (2025 for natural gas, week of 2026-10-05 for propane and heating oil). Very cold days that need backup heat are not modelled. Federal minimum for comparison: 14.3 SEER2 / 7.5 HSPF2.

Similar 1.5 ton models

Grandaire W5H5S18*K*AAA15.5 SEER2 · 8.0 HSPF2
Tempstar T5H6S18*K*AAA15.5 SEER2 · 8.0 HSPF2
Carrier GH5SAN518**AA15.5 SEER2 · 8.0 HSPF2
WeatherMaker PH5SAN518**AB15.5 SEER2 · 8.0 HSPF2
Carrier 27SCA518A**3015.5 SEER2 · 8.0 HSPF2
DETTSON MHD-18 · cold climate15.2 SEER2 · 9.5 HSPF2
Bryant PH5SAN518**AA15.5 SEER2 · 8.0 HSPF2
Ameristar E4HL5018A1000A · cold climate15.2 SEER2 · 8.5 HSPF2

See all 170 1.5 ton central heat pumps, ranked

Source: ENERGY STAR Certified Heat Pumps (U.S. EPA), certification of July 16, 2026. How we use the data.