SplitAtlas

Carrier / Infinity 27

Carrier Infinity 27 18k R-454B 208/230V Mini-Split

Certified capacity
18,000 BTU/h[2]
SEER2
21.5 SEER2[2]
Heating floor
No model-specific value is published on the current Carrier consumer listing
Voltage
230 V[1]
Install path
Professional install

A 1.5-ton Infinity 27 on 230V and R-454B, rated 21.5 SEER2, 12.5 EER2, and 11 HSPF2. Its heating is perfectly flat: 18,000 BTU at 47F, 17F, and 5F alike. It is ENERGY STAR certified and cold-climate designated.

1 zoneProfessional installCurrent

Refrigerant generation

R-454B - current-generation refrigerant

Error Codes
Carrier Infinity 27 18,000 BTU R-454B 208/230V (45MAHAQ18XA3 / 37MAHAQ18AA3)

Image: Carrier

Data completeness: 100%
Last sourced
Jul 27, 2026

SplitAtlas score

8.8 / 10

Methodology
Cooling efficiencyAbove average

(21.5 SEER2) among 18k systems

Heating efficiencyAbove average

(11.0 HSPF2) among 18k systems

Cold-weather performanceTop quartile

(100% heat retained at 5F) among 18k systems

WarrantyAbove average

(10 yr parts / 10 yr compressor) across the catalogue

Feature setAbove average

(6 verified features) across the catalogue

Documentation & partsBelow average

(6 manuals; spec sheet) 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

    quote-only - no retail price to evaluate

Key ratings

Rated cooling

18,000BTU/h[2]

Rated heating

18,000BTU/h[2]

Buyer review snapshot

Install difficulty

Professional install
  • Electrical: 230V.

Alternatives

Availability and price context

  • Warranty warning: Warranty coverage does not apply to any product purchased over the Internet. Online listing: $3,349.99 at HVACDirect; checked Jul 27, 2026; price source is HVACDirect.

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 27, 2026
Page reviewed
Jul 27, 2026
Source-backed records
4
Newest source retrieved
Jul 27, 2026

Warranty tiers

Warranty: 10 years parts and no separate compressor term published as standard.

Review methodology

Model context

Structured ratings
Certification: ENERGY STAR certified and AHRI cold-climate designated. Refrigerant: current low-GWP R-454B.

Strengths

  • Completely flat heat curve, holding the full 18,000 BTU rating all the way down to 5F, an outstanding cold-climate trait.
  • Cold-climate and ENERGY STAR certified, with the durability and warranty support of the Infinity line.

Weaknesses

  • SEER2 of 21.5 is modest for the premium series and closer to value-tier cooling efficiency.
  • 230V only and priced at the Infinity premium.

Climate suitability

Minimum heating ambient
No model-specific value is published on the current Carrier consumer listing
Rated heating at 5F
18,000 BTU/h[2]
Rated heating at 17F
18,000 BTU/h[2]
Rated heating at 47F
18,000 BTU/h[2]

Specifications

Show
Manufacturer
Carrier
Brand
Carrier
Product line
Infinity 27
Model number
45MAHAQ18XA3 indoor / 37MAHAQ18AA3 outdoor
Indoor unit model
45MAHAQ18XA3
Outdoor unit model
37MAHAQ18AA3
Number of zones
1
Max indoor units
not published
Rated cooling capacity
18,000 BTU/h[2]
Rated heating capacity
18,000 BTU/h[2]
Voltage
230 V[1]
MCA
No model-specific value is published on the current Carrier consumer listing
Maximum fuse or breaker size
No model-specific value is published on the current Carrier consumer listing
Breaker needed
not published
SEER2
21.5 SEER2[2]
EER2
12.5 EER2[2]
HSPF2 (Region 4)
11 HSPF2[2]
HSPF2 (Region 5)
not published
COP
not published
COP at 47F
not published
COP at 5F
1.92 COP[2]
Minimum outdoor heating temperature
No model-specific value is published on the current Carrier consumer listing
Minimum outdoor cooling temperature
No model-specific value is published on the current Carrier consumer listing
Maximum outdoor temperature
No model-specific value is published on the current Carrier consumer listing
Indoor noise range
No model-specific value is published on the current Carrier consumer listing
Outdoor noise rating
No model-specific value is published on the current Carrier consumer listing
Indoor weight
No model-specific value is published on the current Carrier consumer listing
Outdoor weight
No model-specific value is published on the current Carrier consumer listing
Refrigerant
R-454B[2]
Refrigerant charge
not published
Manufacturer coverage
not published
Line-set size
No model-specific value is published on the current Carrier consumer listing liquid / No model-specific value is published on the current Carrier consumer listing suction
Included line-set length
Professional installations use separately selected line sets
Maximum line-set length
No model-specific value is published on the current Carrier consumer listing
Max line set per indoor
not published
Maximum elevation difference
No model-specific value is published on the current Carrier consumer listing
Max height between indoor units
not published
Wi-Fi support
No model-specific value is published on the current Carrier consumer listing
Energy Star status
ENERGY STAR certified[3]
AHRI certification number
215323745[2]
Warranty
Standard: 10 yr parts / no separate compressor term (eligible timely registered residential installation). Consumer Choice Warranty: 10-year parts-only or 5-year parts plus 3-year labor for eligible timely registered residential installations; terms and participating dealer requirements apply.
Install path
Professional install
Retail price
online listing with warranty risk: $3,349.99
Available retailers
HVACDirect
Manual links
AHRI public directory record 215323745, ENERGY STAR exact check 215323745, Infinity 27 installation documentation locator, Carrier Infinity 27 Mini Split Heat Pump, HVACDirect exact Carrier affiliate offer carrier-infinity-27-18k-r454b-230v, AHRI Appendix M1 public detail 215323745
Specification sheet
AHRI Appendix M1 public detail 215323745
Last sourced date
Jul 27, 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

Listed at HVACDirect: $3,350. Checked Jul 27, 2026; price source HVACDirect.

View listing at HVACDirect

Electrical requirements

Show
Voltage
230 V[1]
Voltage range
208/230V[1]
Phase
1[1]
Frequency
60 Hz[1]
MCA
No model-specific value is published on the current Carrier consumer listing
Breaker needed
not published
Maximum breaker size
No model-specific value is published on the current Carrier consumer listing
Maximum fuse size
No model-specific value is published on the current Carrier consumer listing
Maximum cooling current
not published
Maximum heating current
not published
Manufacturer wire notes
not published

Installation considerations

Show
Liquid line
No model-specific value is published on the current Carrier consumer listing
Suction line
No model-specific value is published on the current Carrier consumer listing
Line connection type
not published
Precharged length
not published
Included line-set length
Professional installations use separately selected line sets
Maximum line-set length
No model-specific value is published on the current Carrier consumer listing
Max line set per indoor
not published
Max height between indoor units
not published
Indoor dimensions
No model-specific value is published on the current Carrier consumer listing
Outdoor dimensions
No model-specific value is published on the current Carrier consumer listing
Indoor weight
No model-specific value is published on the current Carrier consumer listing
Outdoor weight
No model-specific value is published on the current Carrier consumer listing
Drain size
not published

Related systems and guides

Frequently asked questions

Can I install the Carrier Infinity 27 18,000 BTU R-454B 208/230V (45MAHAQ18XA3 / 37MAHAQ18AA3) myself, or do I need a pro?
Carrier Infinity 27 18,000 BTU R-454B 208/230V (45MAHAQ18XA3 / 37MAHAQ18AA3) 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 27 18,000 BTU R-454B 208/230V (45MAHAQ18XA3 / 37MAHAQ18AA3) keep heating in a cold winter?
The manufacturer publishes 18,000 BTU/h of heating output at 5F. Certified heating efficiency is 11 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 27 18,000 BTU R-454B 208/230V (45MAHAQ18XA3 / 37MAHAQ18AA3) need?
Published electrical requirements: 230 V voltage, No model-specific value is published on the current Carrier consumer listing minimum circuit ampacity, and No model-specific value is published on the current Carrier consumer listing 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 is No model-specific value is published on the current Carrier consumer listing. Longer runs than the included set allows typically mean added refrigerant and a pro visit, so measure the planned routing before ordering.
What warranty does the Carrier Infinity 27 18,000 BTU R-454B 208/230V (45MAHAQ18XA3 / 37MAHAQ18AA3) carry?
The manufacturer publishes these warranty tiers: Standard: 10 yr parts / no separate compressor term (eligible timely registered residential installation). Registration requirements and proof of qualified installation commonly affect coverage, so read the warranty terms before install day.

Data sources

Show
  1. Carrier Corporation: Carrier Infinity 27 Mini Split Heat PumpSourced - manufacturer product page

    Covers Frequency, Phase, Voltage, Voltage range, Legacy warranty value, Standard compressor warranty status and more

  2. Air-Conditioning, Heating, and Refrigeration Institute: AHRI Appendix M1 public detail for 37MAHAQ18AA3 / 45MAHAQ18XA3Sourced - AHRI directory

    Covers AHRI certification number, performance_spec.cold_climate_designation, Rated cooling capacity, COP at 5F, EER2, Rated heating capacity and more

  3. ENERGY STAR: ENERGY STAR exact row check for AHRI 215323745Sourced - Energy Star listing

    Covers Energy Star status

  4. HVACDirect: HVACDirect exact Carrier offer for 37MAHAQ18AA3 / 45MAHAQ18XA3Sourced - retailer listing

    Covers Retail price

Last updated

Jul 27, 2026