What is the SEER2 rating of the ZERO ZMSB-24HV-USHHCR2-O?

The ZERO ZMSB-24HV-USHHCR2-O is rated at up to 22.3 SEER2 and 12.5 EER2 for cooling and up to 13.3 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with.

Is the ZERO ZMSB-24HV-USHHCR2-O good for cold climates?

Yes. At least one certified matchup meets the ENERGY STAR cold-climate criteria, delivering up to 24,000 BTU/h at 5°F with a COP of 2.00, so it is still 2.0 times as efficient as electric resistance heat at that temperature.

How much does the ZERO ZMSB-24HV-USHHCR2-O cost to run per year?

At its rated efficiency it costs about $484-$1,247 a year in electricity in large U.S. cities, depending on climate and local rates - for example $590 in Phoenix and $1,036 in Minneapolis. The calculator on this page works it out for your city and compares it with your current system.

Is the ZERO ZMSB-24HV-USHHCR2-O the same as the Elios ESHMA24C2AN1?

Yes, as far as the certified ratings go. ENERGY STAR lists 4 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 ZERO ZMSB-24HV-USHHCR2-O?

ENERGY STAR lists 1 certified combination for this outdoor unit. The highest-rated one uses ZMSB-24HV-USHHCR2-I.

24,000 BTU mini-split heat pump · ZMSB Series

ZERO ZMSB-24HV-USHHCR2-O

Average cooling efficiency and excellent heating efficiency for a 24,000 BTU mini-split heat pump, and certified for cold climates.

Ranks #158 of 430 24,000 BTU mini-splits for cooling efficiency, and costs about $526 a year to run in a mixed climate like Atlanta.

SEER2: 22.3 Cooling efficiency over a season
Average · beats 53%
HSPF2: 13.3 Heating efficiency over a season
Excellent · beats 95%
EER2: 12.5 Cooling efficiency on a 95°F day
Average · beats 44%
Heat at 5°F: 24,000 BTU/h92% of its 47°F output
Average · beats 48%

A good fit if…

Your winters get properly cold - it is ENERGY STAR cold-climate certified, with 24,000 BTU/h at 5°F.
It will heat most of the year - its HSPF2 beats 95% of mini-splits.
You want steady temperatures and quiet running - the compressor varies its speed.

Think twice if…

Nothing stands out - its ratings have no weak spot for its class.

Calculate my running cost

Details

Specifications24,000 BTU, R-454B

General
Brand	ZERO
Also sold as	Elios, PerfectAire, Cadet
Outdoor unit model	ZMSB-24HV-USHHCR2-O
Series	ZMSB Series
Type	Mini-split heat pump
Nominal size	24,000 BTU
CompressorVariable-speed units run longer at low power	Continuously variable
Refrigerant	R-454B
Connected (smart) capable	No
On the market since	November 11, 2024
Last certified	May 6, 2026
Cooling
SEER2Seasonal efficiency, higher is better	22.3 (range 22.3)
EER2Efficiency at 95°F outdoors	12.5
Cooling capacity	23,000 BTU/h
Heating
HSPF2Seasonal efficiency, higher is better	13.3
Capacity at 47°F	26,000 BTU/h
Capacity at 17°F	23,000 BTU/h
Capacity at 5°F	24,000 BTU/h
COP at 5°F2.0 = twice as efficient as a space heater	2.00
ENERGY STAR cold climate	Yes

Heating output as it gets colder92% kept at 5°F

Every heat pump delivers less heat as the outdoor temperature drops. Certified output of its matchup with ZMSB-24HV-USHHCR2-I at the standard test temperatures, in BTU/h:

Certified matchups1 indoor units

The same outdoor unit scores differently with each indoor unit. Ask your installer for the AHRI reference number of the exact system you are quoted.

Indoor unit	SEER2	EER2	HSPF2	Heat @5°F	AHRI ref.
ZMSB-24HV-USHHCR2-I · cold climate	22.3	12.5	13.3	24,000	216097676

Same unit, other model numbers3

These model numbers have exactly the same certified ratings and matchups as the ZERO ZMSB-24HV-USHHCR2-O: the same equipment under another brand, or a variant code for voltage, colour or market. Everything on this page applies to them.

Elios ESHMA24C2AN1
PerfectAire 4PAMSHH24-SZO
Cadet 500006883

Yearly running cost in 10 large cities$484-$1,247

Phoenix, AZ$590/yr
Miami, FL$484/yr
Houston, TX$529/yr
Atlanta, GA$526/yr
Los Angeles, CA$510/yr
New York, NY$1,247/yr
Chicago, IL$1,010/yr
Denver, CO$838/yr
Seattle, WA$514/yr
Minneapolis, MN$1,036/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 ZERO ZMSB-24HV-USHHCR2-O?: The ZERO ZMSB-24HV-USHHCR2-O is rated at up to 22.3 SEER2 and 12.5 EER2 for cooling and up to 13.3 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with.
Is the ZERO ZMSB-24HV-USHHCR2-O good for cold climates?: Yes. At least one certified matchup meets the ENERGY STAR cold-climate criteria, delivering up to 24,000 BTU/h at 5°F with a COP of 2.00, so it is still 2.0 times as efficient as electric resistance heat at that temperature.
How much does the ZERO ZMSB-24HV-USHHCR2-O cost to run per year?: At its rated efficiency it costs about $484-$1,247 a year in electricity in large U.S. cities, depending on climate and local rates - for example $590 in Phoenix and $1,036 in Minneapolis. The calculator on this page works it out for your city and compares it with your current system.
Is the ZERO ZMSB-24HV-USHHCR2-O the same as the Elios ESHMA24C2AN1?: Yes, as far as the certified ratings go. ENERGY STAR lists 4 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 ZERO ZMSB-24HV-USHHCR2-O?: ENERGY STAR lists 1 certified combination for this outdoor unit. The highest-rated one uses ZMSB-24HV-USHHCR2-I.
What refrigerant does the ZERO ZMSB-24HV-USHHCR2-O 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 $582/yrYou save $653/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 ZERO ZMSB-24HV-USHHCR2-O

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: $582
Current system, per year: $1,235
You save per year: $653
Payback: 13.0 years
Net after 10 years: -$1,970

Cooling $363Heating $219Electricity used: 3,637 kWhSaved vs. a minimum-efficiency heat pump: $372

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 24,000 BTU models

TRUST AIR CONDITIONERS OAH24H/O6S4P · cold climate22.3 SEER2 · 13.3 HSPF2
Airquest DLCSRBH24AAK · cold climate22.3 SEER2 · 11.5 HSPF2
SLIMAIR SHC24AH2AG · cold climate22.3 SEER2 · 13.3 HSPF2
Breeze33 HSZ24H424ZMO · cold climate22.3 SEER2 · 11.5 HSPF2
Mainline ML24HP230NEXH-O · cold climate22.3 SEER2 · 13.3 HSPF2
Cooper&Hunter CH-HPR24-230VO · cold climate22.3 SEER2 · 11.5 HSPF2
Convectair 500004496 · cold climate22.3 SEER2 · 13.3 HSPF2
KARDA 3KARDA24SZO · cold climate22.3 SEER2 · 11.5 HSPF2

See all 430 24,000 BTU mini-splits, ranked

Source: ENERGY STAR Certified Heat Pumps (U.S. EPA), certification of May 6, 2026. How we use the data.