Bosch / Climate 5000 Gen 4
Bosch Climate 5000 G4 12k Max R-454B Mini-Split
The 12k Max Performance brings that same flagship cold-weather heating to a standard-size room. It holds a flat 12,000 BTU of heat from 47F down to 17F and still 11,500 BTU at 5F - the winter consistency that is the whole reason to buy this tier - and it cools efficiently at 25.4 SEER2.
One honest quirk: despite the identical heat curve, its heating-season efficiency rating (HSPF2 10.5) actually trails the smaller 9k, so it is not quite the cheapest of the two to heat with. Like the rest of the tier it is premium, dealer-installed Bosch equipment on current R-454B refrigerant, ENERGY STAR certified and cold-climate rated.
Refrigerant generation
R-454B - current-generation refrigerant
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Image: Hydrowest Products
- Last sourced
- Jul 26, 2026
SplitAtlas score
9.1 / 10
(25.4 SEER2) among 12k systems
(10.5 HSPF2) among 12k systems
(5F certified capacity: 95.8% of the 47F rating; -22 F heating floor) among 12k systems
(19.5 dBA indoor min / 56 dBA outdoor) among 12k systems
(10 yr parts / 10 yr compressor) across the catalogue
(6 verified features) across the catalogue
(6 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
Best-fit use cases
A strong choice for a standard bedroom or living room in a cold climate that wants flagship winter heat retention without stepping up to an 18k head.
Buyer review snapshot
Best for / skip if
Best for
- Top efficiency shortlists; SEER2 is 25.4.
Install difficulty
- Electrical: 230V; MCA 15 A; breaker/fuse 15 A.
- Line set: connection type not sourced; precharged 24.6 ft; max 82 ft.
Availability and price context
This system needs a professional install, so its real price is an installed quote that depends on your home. We don't link to a listing for this exact model; get installation quotes to price it.
Source date
- Model data sourced
- Jul 26, 2026
- Page reviewed
- Jul 22, 2026
- Source-backed records
- 6
- Newest source retrieved
- Jul 26, 2026
Warranty tiers
- Base
- 10 yr parts / 10 yr compressor - limited residential warranty terms
The score uses Base. 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
- Holds a flat 12,000 BTU of heat from 47F to 17F and still 11,500 BTU at 5F - dependable warmth deep into winter.
- Cools efficiently at 25.4 SEER2 on current R-454B refrigerant.
- Bosch's dealer network and warranty stand behind the install.
Weaknesses
- Its HSPF2 of 10.5 trails the smaller 9k Max Performance despite the identical heat curve.
- Flagship, dealer-only pricing - there is no retail or DIY path for this tier.
Climate suitability
- Minimum heating ambient
- -22 F[1]
- Certified heating at 5F
- 11,500 BTU/h[3]
- Rated heating at 17F
- 12,000 BTU/h[3]
- Rated heating at 47F
- 12,000 BTU/h[3]
Specifications
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- Manufacturer
- Bosch
- Brand
- Bosch
- Product line
- Climate 5000 Gen 4
- Model number
- BMS500-AAU012-1AHWXD indoor / BMS500-AAS012-1CSXHD outdoor
- Indoor unit model
- BMS500-AAU012-1AHWXD
- Outdoor unit model
- BMS500-AAS012-1CSXHD
- Number of zones
- 1
- Max indoor units
- not published
- Rated cooling capacity
- 12,000 BTU/h[3]
- Rated heating capacity
- 12,000 BTU/h[3]
- Voltage
- 230 V[1]
- MCA
- 15 A[1]
- Maximum fuse or breaker size
- 15 A[1]
- Breaker needed
- not published
- SEER2
- 25.4 SEER2[3]
- EER2
- 13.4 EER2[3]
- HSPF2 (Region 4)
- 10.5 HSPF2[3]
- HSPF2 (Region 5)
- not published
- COP
- not published
- COP at 47F
- 3.76 COP[1]
- COP at 5F
- 1.8 COP[3]
- Minimum outdoor heating temperature
- -22 F[1]
- Minimum outdoor cooling temperature
- -22 F[1]
- Maximum outdoor temperature
- 122 F[1]
- Indoor noise range
- 19.5-47 dB(A)[1]
- Outdoor noise rating
- 56 dBA[1]
- Indoor weight
- 22.93 lb[1]
- Outdoor weight
- 72.75 lb[1]
- Refrigerant
- R-454B[3]
- Refrigerant charge
- 35.27 oz[1]
- Manufacturer coverage
- not published
- Line-set size
- 1/4 in liquid / 3/8 in suction
- Included line-set length
- Bosch submittals publish field piping sizes and precharged refrigerant length, but do not specify an included line set for these professional-install systems.
- Maximum line-set length
- 82 ft[1]
- Max line set per indoor
- not published
- Maximum elevation difference
- 49.2 ft[1]
- Max height between indoor units
- not published
- Wi-Fi support
- not supported[2]
- Energy Star status
- ENERGY STAR certified[5]
- AHRI certification number
- 215223282[3]
- Warranty
- Base: 10 yr parts / 10 yr compressor (limited residential warranty terms). Score uses Base.. 10-year compressor / 10-year parts limited residential warranty; terms and field-installed component limits apply.
- Install path
- Professional install
- Retail price
- Installed quote only
- Available retailers
- not published
- Manual links
- AHRI public directory record 215223282, ENERGY STAR exact check 215223282, Climate 5000 Ductless System Mini-Split Heat Pump (R-454B Version), Bosch Climate 5000 ductless mini-split submittal sheet directory, BMS500-AAU012-1AHWXD & BMS500-AAS012-1CSXHD Bosch Climate 5000 Gen 4 R-454B submittal
- Specification sheet
- not published
- Last sourced date
- Jul 26, 2026
Installation considerations
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- Liquid line
- 1/4 in[1]
- Suction line
- 3/8 in[1]
- Line connection type
- not published
- Precharged length
- 24.6 ft[1]
- Included line-set length
- Bosch submittals publish field piping sizes and precharged refrigerant length, but do not specify an included line set for these professional-install systems.
- Maximum line-set length
- 82 ft[1]
- Max line set per indoor
- not published
- Max height between indoor units
- not published
- Indoor dimensions
- 31.42 x 9.21 x 11.85 in[1]
- Outdoor dimensions
- 31.69 x 12.99 x 21.81 in[1]
- Indoor weight
- 22.93 lb[1]
- Outdoor weight
- 72.75 lb[1]
- Drain size
- not published
Related systems and guides
- More Bosch systems
- Bosch Climate 5000 G4 12k Regular R-454B 115V Mini-Split
- Bosch Climate 5000 G4 12k Regular R-454B Mini-Split
- Bosch Climate 5000 A B Legacy 12k Regular R-410A Mini-Split
Previous generation
- Bosch Climate 5000 Model C Legacy 12k Regular R-410A 115V 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?
- Bosch mini split review: is Bosch any good?
- The best 12,000 BTU mini splits of 2026
- 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
- The mini split defrost cycle, explained
- The best DIY mini splits of 2026
- What "DIY mini split" actually means
- How to install a mini split (DIY overview)
- Mini split not heating
- Mini split indoor unit freezing up
- Mini split remote not working
- Mini split lights blinking
- Mini split Wi-Fi not connecting
- Line sets
- Line-set covers
Frequently asked questions
- Can I install the Bosch Climate 5000 Gen 4 R-454B 12,000 BTU Max Performance (BMS500-AAU012-1AHWXD / BMS500-AAS012-1CSXHD) myself, or do I need a pro?
- Bosch Climate 5000 Gen 4 R-454B 12,000 BTU Max Performance (BMS500-AAU012-1AHWXD / BMS500-AAS012-1CSXHD) 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 Bosch Climate 5000 Gen 4 R-454B 12,000 BTU Max Performance (BMS500-AAU012-1AHWXD / BMS500-AAS012-1CSXHD) keep heating in a cold winter?
- The AHRI/ENERGY STAR certification lists 11,500 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 Bosch Climate 5000 Gen 4 R-454B 12,000 BTU Max Performance (BMS500-AAU012-1AHWXD / BMS500-AAS012-1CSXHD) need?
- Published electrical requirements: 230 V voltage, 15 A minimum circuit ampacity, and 15 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 is 82 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 Bosch Climate 5000 Gen 4 R-454B 12,000 BTU Max Performance (BMS500-AAU012-1AHWXD / BMS500-AAS012-1CSXHD) carry?
- The manufacturer publishes these warranty tiers: Base: 10 yr parts / 10 yr compressor (limited residential warranty terms). Score uses Base.. Registration requirements and proof of qualified installation commonly affect coverage, so read the warranty terms before install day.
Data sources
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- Bosch Thermotechnology Corp.: BMS500-AAU012-1AHWXD & BMS500-AAS012-1CSXHD Bosch Climate 5000 Gen 4 submittalSourced - manufacturer technical document
Covers Frequency, electrical_spec.indoor_mca_amps, Maximum breaker size, Maximum fuse size, Minimum circuit ampacity, Phase and more
- Bosch Thermotechnology Corp.: Air-to-Air R-454B Heat Pump Systems FAQSourced - manufacturer product page
Covers Wi-Fi support
- AHRI Directory: AHRI public directory record 215223282Sourced - AHRI directory
Covers AHRI certification number, Rated cooling capacity, COP at 5F, EER2, Rated heating capacity, HSPF2 (Region 4) and more
- Air-Conditioning, Heating, and Refrigeration Institute: AHRI Appendix M1 public detail for BMS500-AAS012-1CSXHD / BMS500-AAU012-1AHWXDSourced - AHRI directory
Covers performance_spec.cold_climate_designation, system.lifecycle_status
- ENERGY STAR Certified Air-Source Heat Pumps Directory: ENERGY STAR record 3554538 for BMS500-AAS012-1CSXHD / BMS500-AAU012-1AHWXDSourced - Energy Star listing
Covers Energy Star status
- Bosch Thermotechnology Corp.: Climate 5000 Ductless System Mini-Split Heat Pump (R-454B Version) manufacturer pageSourced - manufacturer product page
Covers Legacy compressor warranty value, Legacy warranty value, Base compressor warranty, Base warranty conditions, Base parts warranty, Warranty notes
Last updated
Jul 22, 2026