Carrier / Infinity 25
Carrier Infinity 25 18k R-454B 208/230V 3-Zone Mini-Split
The Carrier Infinity 25 3-Zone 18k (37MGHAQ18CA3) is Carrier's premium cold-climate multi-zone, and unlike the dealer-quoted Performance line, this Infinity condenser is stocked and purchasable at retail - a priced condenser you can buy, still professionally installed. It carries a certified nominal SEER2 of 25, a high EER2 of 15, and HSPF2 10.5, is ENERGY STAR certified and AHRI cold-climate designated, on current low-GWP R-454B refrigerant.
Cooling is rated at 19000 BTU, and the heating is the story: 20000 BTU at 47F, a full 20000 still at 17F, and 19000 at 5F. That is genuine deep-cold performance - heat that holds essentially flat as the temperature drops.
Professional installation required.
Refrigerant generation
R-454B - current-generation refrigerant
This brand doesn't honor its warranty on systems bought online. Buy it through a local contractor who installs it: get quotes from installers in your area, and ask whether they're an authorized dealer for this brand.
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Image: Carrier
- Last sourced
- Jul 28, 2026
SplitAtlas score
8.9 / 10
(25.0 SEER2) among 18k systems
(10.5 HSPF2) among 18k systems
(5F certified capacity: 95% of the 47F rating; -22 F heating floor) among 18k systems
(10 yr parts, no separate compressor term) across the catalogue
(7 verified features) across the catalogue
(7 manuals) across the catalogue
Not evaluated
- Installation accessibility — not applicable (professional install)N/A
professional install - DIY-accessibility not applicable
- Price-to-value — not evaluatedN/A
This is a professionally installed, quote-only system, so we can't score its price. Get an installed quote to compare real cost.
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Key ratings
Buyer review snapshot
Best for / skip if
Best for
- 3-zone projects in the 18k outdoor capacity class.
- Top efficiency shortlists; SEER2 is 25.
Install difficulty
- Electrical: 230V; MCA 17.5 A; breaker/fuse 20 A.
- Line set: Flared line connections; precharged 24.6 ft; max 196.9 ft.
- 3-zone condenser; indoor-head matching and branch layout are part of the job.
Availability and price context
- Carrier doesn't honor its warranty on systems bought online. Buy it through an authorized dealer or contractor.
Purchase channel policy
Carrier's ductless warranty excludes products purchased over the Internet; buyers should treat public online carts as outside the warranty-covered purchase channel.
- Warranty consequence
- Warranty coverage does not apply to any product purchased over the Internet.
- Authorized channel
- Licensed HVAC technician installation with defective parts returned to the distributor through a registered servicing dealer; not an internet purchase.
Any online offer for this brand should be treated as a warranty-risk warning, not a recommendation.
Compare online-purchase warranty rules by brand
Source: Carrier Corporation: CAC/BDP Limited Warranty Certificate - Limited Warranty for Ductless Split Units; retrieved Aug 15, 2026.
Source date
- Model data sourced
- Jul 28, 2026
- Page reviewed
- Jul 28, 2026
- Source-backed records
- 5
- Newest source retrieved
- Jul 28, 2026
Warranty tiers
- Registered
- 10 yr parts / no separate compressor term - eligible timely registered residential installation
- Dealer alternative
- 5 yr parts / no separate compressor term - Consumer Choice dealer alternative: 5-year parts plus 3-year labor through a participating dealer
The score uses Registered. Additional published terms are shown for reference and not counted in the score.
Model context
- Structured ratings
- Certification: ENERGY STAR certified and AHRI cold-climate designated. Refrigerant: current low-GWP R-454B. Minimum heating ambient: -22 F.
Strengths
- Buyable equipment - a stocked, priced Infinity condenser you can purchase, professionally installed.
- Heating holds flat into deep cold: 20000 BTU at both 47F and 17F, 19000 at 5F.
- High EER2 of 15 and HSPF2 10.5, ENERGY STAR certified.
- AHRI cold-climate designated on current low-GWP R-454B.
Weaknesses
- Professional installation still required - equipment you buy, not a DIY kit.
- Three zones is the entry step; more rooms need a larger Infinity condenser.
- Multi-zone part-load penalty when only one head is running.
Climate suitability
- Minimum heating ambient
- -22 F[4]
- Certified heating at 5F
- 19,000 BTU/hNon-Ducted Indoor Units[2]
- Rated heating at 17F
- 20,000 BTU/hNon-Ducted Indoor Units[2]
- Rated heating at 47F
- 20,000 BTU/hNon-Ducted Indoor Units[2]
Specifications
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- Manufacturer
- Carrier
- Brand
- Carrier
- Product line
- Infinity 25
- Model number
- 37MGHAQ18CA3
- Indoor unit model
- Depends on the indoor units you choose
- Outdoor unit model
- 37MGHAQ18CA3
- Number of zones
- 3
- Max indoor units
- 3 units[1]
- Rated cooling capacity
- 19,000 BTU/hNon-Ducted Indoor Units[2]
- Rated heating capacity
- 20,000 BTU/hNon-Ducted Indoor Units[2]
- Voltage
- 230 V[1]
- MCA
- 17.5 A[1]
- Maximum fuse or breaker size
- 20 A[1]
- Breaker needed
- not published
- SEER2
- 25 SEER2Non-Ducted Indoor Units[2]
- EER2
- 15 EER2Non-Ducted Indoor Units[2]
- HSPF2 (Region 4)
- 10.5 HSPF2Non-Ducted Indoor Units[2]
- HSPF2 (Region 5)
- Varies by indoor-unit combination
- COP
- not published
- COP at 47F
- not published
- COP at 5F
- 2 COPNon-Ducted Indoor Units[2]
- Minimum outdoor heating temperature
- -22 F[4]
- Minimum outdoor cooling temperature
- -22 F[4]
- Maximum outdoor temperature
- 122 F[4]
- Indoor noise range
- Depends on the indoor units you choose
- Outdoor noise rating
- 61.5 dBA[1]
- Indoor weight
- Depends on the indoor units you choose
- Outdoor weight
- 137.35 lb[1]
- Refrigerant
- R-454B[2]
- Refrigerant charge
- 78.24 oz[1]
- Manufacturer coverage
- not published
- Line-set size
- 1/4 in x 3 liquid / 3/8 in x 3 suction
- Included line-set length
- Depends on the indoor units you choose
- Maximum line-set length
- 196.9 ft[1]
- Max line set per indoor
- 98.4 ft[1]
- Maximum elevation difference
- 49.21 ft[1]
- Max height between indoor units
- 33 ft[1]
- Wi-Fi support
- Depends on the indoor units you choose
- Energy Star status
- ENERGY STAR certified[3]
- AHRI certification number
- 215357433Non-Ducted Indoor Units[2]
- Warranty
- Registered: 10 yr parts / no separate compressor term (eligible timely registered residential installation); Dealer alternative: 5 yr parts / no separate compressor term (Consumer Choice dealer alternative: 5-year parts plus 3-year labor through a participating dealer). Score uses Registered. Additional published terms are shown for reference and not counted in the score.. Consumer Choice Warranty: 10-year parts-only option or 5-year parts plus 3-year labor option
- Install path
- Professional install
- Retail price
- online listing with warranty risk: $2,999.99
- Available retailers
- HVACDirect
- Manual links
- AHRI public detail 215357433, ENERGY STAR exact row 215357433, Infinity 25 Carrier ductless current brochure, Carrier Ductless Systems compatibility charts, Carrier Infinity 25 Multi-Zone High-Heat Mini Split Heat Pump with Basepan Heater, Carrier R-454B ductless Consumer Choice Warranty
- Specification sheet
- not published
- Last sourced date
- Jul 28, 2026
Retail purchase context
Warranty consequence
Warranty coverage does not apply to any product purchased over the Internet.
Any online offer for this brand should be treated as a warranty-risk warning, not a recommendation.
Authorized channel: Licensed HVAC technician installation with defective parts returned to the distributor through a registered servicing dealer; not an internet purchase.
Some retailer links may earn us a commission at no extra cost; paid relationships never change scores or recommendations. Affiliate disclosure
Paid link
Warranty-risk online listing
Last seen at HVACDirect on Jul 28, 2026: $3,000
Installation considerations
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- Liquid line
- 1/4 in x 3[1]
- Suction line
- 3/8 in x 3[1]
- Line connection type
- Flared line connections[1]
- Precharged length
- 24.6 ft[1]
- Included line-set length
- Depends on the indoor units you choose
- Maximum line-set length
- 196.9 ft[1]
- Max line set per indoor
- 98.4 ft[1]
- Max height between indoor units
- 33 ft[1]
- Indoor dimensions
- Depends on the indoor units you choose
- Outdoor dimensions
- 37.24 x 16.14 x 31.89 in[1]
- Indoor weight
- Depends on the indoor units you choose
- Outdoor weight
- 137.35 lb[1]
- Drain size
- not published
Related systems and guides
- More Carrier systems
- Bosch Climate 5000 G4 18k Max R-454B 208/230V 3-Zone Mini-Split
- Cooper Hunter Hyper Heat 19k HZ R-454B 208/230V 3-Zone Mini-Split
- Carrier Performance 26 18k R-454B 208/230V Mini-Split
- Carrier Infinity Legacy 22k A/A R-410A 208/230V Mini-Split
Previous generation
- Guide library
- Mini split buying guide
- Single-zone vs multi-zone mini splits
- Troubleshooting
- Do mini splits work in cold weather?
- Carrier mini split review: is Carrier any good?
- The best multi-zone mini splits of 2026
- The best 3-zone mini splits of 2026
- How to size a multi-zone mini split
- Not every multi-zone condenser lets you mix head types
- How much does a multi-zone mini split cost?
- The best cold-climate mini splits of 2026
- The best mini splits for heating of 2026
- Mini split heating capacity in the cold: what your unit actually delivers at 5F
- One room won't heat or cool on a multi-zone mini split
- Mini split not heating
- Mini split indoor unit freezing up
- Mini split leaking water
- Mini split smells bad
- Line sets
- Line-set covers
Frequently asked questions
- Can I install the Carrier Infinity 25 3-Zone 18,000 BTU R-454B 208/230V (37MGHAQ18CA3) myself, or do I need a pro?
- Carrier Infinity 25 3-Zone 18,000 BTU R-454B 208/230V (37MGHAQ18CA3) is built for professional installation: the line set must be flared, evacuated, and charged, which requires EPA-certified refrigerant handling. Installing it outside the manufacturer's requirements can void the warranty, so budget for a qualified HVAC installer.
- Will the Carrier Infinity 25 3-Zone 18,000 BTU R-454B 208/230V (37MGHAQ18CA3) keep heating in a cold winter?
- The AHRI/ENERGY STAR certification lists 19,000 BTU/h of heating capacity at 5F. Rated heating operation extends down to -22 F. Certified heating efficiency is 10.5 HSPF2. Match those numbers against your climate's design temperature - in cold regions, output at 5F matters far more than the nameplate capacity measured at 47F.
- What electrical circuit does the Carrier Infinity 25 3-Zone 18,000 BTU R-454B 208/230V (37MGHAQ18CA3) need?
- Published electrical requirements: 230 V voltage, 17.5 A minimum circuit ampacity, and 20 A maximum breaker or fuse sizing. Confirm the final circuit against the unit nameplate and local code with a licensed electrician.
- How far can the outdoor unit be from the indoor head?
- The published maximum line-set length from the outdoor unit to one indoor head is 98.4 ft. The combined piping limit across all heads is 196.9 ft. The outdoor unit's factory charge covers up to 24.6 ft of line; longer runs need added refrigerant. Measure the planned routing before ordering.
- What warranty does the Carrier Infinity 25 3-Zone 18,000 BTU R-454B 208/230V (37MGHAQ18CA3) carry?
- The manufacturer publishes these warranty tiers: Registered: 10 yr parts / no separate compressor term (eligible timely registered residential installation); Dealer alternative: 5 yr parts / no separate compressor term (Consumer Choice dealer alternative: 5-year parts plus 3-year labor through a participating dealer). Score uses Registered. Additional published terms are shown for reference and not counted in the score.. Registration requirements and proof of qualified installation commonly affect coverage, so read the warranty terms before install day.
Data sources
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- Carrier Corporation: Carrier Infinity 25 37MG multi-zone compatibility and technical evidenceSourced - manufacturer technical document
Covers Frequency, Maximum breaker size, Maximum fuse size, Minimum circuit ampacity, Phase, Voltage and more
- Air-Conditioning, Heating, and Refrigeration Institute: AHRI public detail 215357433Sourced - AHRI directory
Covers AHRI certification number, performance_spec.cold_climate_designation, Rated cooling capacity, COP at 5F, EER2, Rated heating capacity and more
- U.S. Environmental Protection Agency ENERGY STAR: ENERGY STAR exact row check for AHRI 215357433Sourced - Energy Star listing
Covers Energy Star status
- Carrier Corporation: Carrier Infinity 25 Multi-Zone High-Heat Mini Split Heat Pump with Basepan HeaterSourced - manufacturer product page
Covers Minimum outdoor cooling temperature, Minimum outdoor heating temperature, Maximum outdoor temperature, Additional compressor warranty status, Additional published warranty conditions, Additional published parts warranty and more
- HVACDirect: HVACDirect exact Carrier offer for 37MGHAQ18CA3Sourced - retailer listing
Covers Retail price
Last updated
Jul 28, 2026