Bosch / Climate 5000 Gen 4 R-454B
Bosch Climate 5000 Gen 4 18,000 BTU R-454B Max Performance (BMS500-AAU018-1AHWXD / BMS500-AAS018-1CSXHD)
Model data is drawn from manufacturer, retailer, and certification sources. Missing specifications remain marked as not published.
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Data completeness: 97%
- Last verified
- Jul 22, 2026
SplitAtlas score
8.8 / 10
Cooling efficiency21.0
Heating efficiency46.1
Cold-weather performance100.0
Noise100.0
Warranty100.0
Feature set42.9
Documentation & parts50.0
Not evaluated
- Installation accessibility — not applicable (professional install)N/A
professional install - DIY-accessibility not applicable
- Price-to-value — not evaluatedN/A
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Bosch Climate 5000 Gen 4 18,000 BTU R-454B Max Performance (BMS500-AAU018-1AHWXD / BMS500-AAS018-1CSXHD) review summary
The Max Performance 18k is a cold-climate standout: it holds its full 18,000 BTU of rated heat at 47F, 17F, and 5F - flat, no falloff - and is rated to operate to -22F, with the line's best 1.5-ton seasonal heating (HSPF2 11). Cooling efficiency (SEER2 21.4) steps down from the regular version, which is the expected trade for that cold-weather muscle.
Rated cooling
18,000BTU/hVerified - AHRI directory
Rated heating
18,000BTU/hVerified - AHRI directory
Bosch Climate 5000 Gen 4 18,000 BTU R-454B Max Performance (BMS500-AAU018-1AHWXD / BMS500-AAS018-1CSXHD) best-fit use cases
A large living room or finished basement in a cold climate where holding full heat output through a hard winter is the priority.
Bosch Climate 5000 Gen 4 18,000 BTU R-454B Max Performance (BMS500-AAU018-1AHWXD / BMS500-AAS018-1CSXHD) specifications
- Manufacturer
- Bosch
- Brand
- Bosch
- Product line
- Climate 5000 Gen 4 R-454B
- Model number
- BMS500-AAU018-1AHWXD indoor / BMS500-AAS018-1CSXHD outdoor
- Indoor unit model
- BMS500-AAU018-1AHWXD
- Outdoor unit model
- BMS500-AAS018-1CSXHD
- Number of zones
- 1
- Max indoor units
- not published
- Rated cooling capacity
- 18,000 BTU/hVerified - AHRI directory
- Rated heating capacity
- 18,000 BTU/hVerified - AHRI directory
- Voltage
- 230 VVerified - manufacturer technical document
- MCA
- 19 AVerified - manufacturer technical document
- Maximum fuse or breaker size
- 20 AVerified - manufacturer technical document
- Breaker needed
- not published
- SEER2
- 21.4 SEER2Verified - AHRI directory
- EER2
- 12.5 EER2Verified - AHRI directory
- HSPF2 (Region 4)
- 11 HSPF2Verified - AHRI directory
- HSPF2 (Region 5)
- not published
- COP
- not published
- COP at 47F
- 3.26 COPVerified - manufacturer technical document
- COP at 5F
- 1.92 COPVerified - AHRI directory
- Minimum outdoor heating temperature
- -22 FVerified - manufacturer technical document
- Minimum outdoor cooling temperature
- -22 FVerified - manufacturer technical document
- Maximum outdoor temperature
- 122 FVerified - manufacturer technical document
- Indoor noise range
- 19.5-49.5 dB(A)Verified - manufacturer technical document
- Outdoor noise rating
- 59 dBAVerified - manufacturer technical document
- Indoor weight
- 27.34 lbVerified - manufacturer technical document
- Outdoor weight
- 99.87 lbVerified - manufacturer technical document
- Refrigerant
- R-454BVerified - AHRI directory
- Refrigerant charge
- 55.38 ozVerified - manufacturer technical document
- Manufacturer coverage
- not published
- Line-set size
- 1/4 in liquid / 1/2 in suction
- Included line-set length
- Bosch submittals publish field piping sizes, precharged refrigerant length, and accessory line sets, but do not specify an included line set for these professional-install systems.
- Maximum line-set length
- 98.4 ftVerified - manufacturer technical document
- Max line set per indoor
- not published
- Maximum elevation difference
- 65.6 ftVerified - manufacturer technical document
- Max height between indoor units
- not published
- Wi-Fi support
- not published
- Energy Star status
- certifiedVerified - Energy Star listing
- AHRI certification number
- 215223286Verified - AHRI directory
- Warranty
- 10 years parts / 10 years compressor. 10-year compressor / 10-year parts limited residential warranty; terms and field-installed component limits apply.
- DIY installation status
- Professional install
- Retail price
- Exact HVACDirect SKU searches for BMS500-AAS018-1CSXHD, BMS500-AAU018-1AHWXD returned 403 status and no exact product page with visible price on 2026-07-22; no affiliate offer was attached.
- Installation type
- Professional install
- Available retailers
- not published
- Manual links
- AHRI certificate 215223286, AHRI public directory record 215223286, ENERGY STAR record 3554542 for BMS500-AAS018-1CSXHD / BMS500-AAU018-1AHWXD, HVACDirect exact Bosch model search summary, Bosch Climate 5000 Gen 4 Wall Mounted Ductless Split IOM, Air-to-Air R-454B Heat Pump Systems FAQ snapshot, Bosch Climate 5000 R-454B source links manifest, Climate 5000 Ductless System Mini-Split Heat Pump (R-454B Version) manufacturer page snapshot, Bosch heat pump and geothermal warranty documents page snapshot, Bosch Climate 5000 Gen 4 Wall Mounted Ductless Split Service Manual, Bosch Climate 5000 Gen 4 18,000 BTU R-454B Max Performance (BMS500-AAU018-1AHWXD / BMS500-AAS018-1CSXHD) engineering submittal sheet, Bosch Climate 5000 Gen 4 Wall Mounted Ductless Split User Manual
- Specification sheet
- Bosch Climate 5000 Gen 4 18,000 BTU R-454B Max Performance (BMS500-AAU018-1AHWXD / BMS500-AAS018-1CSXHD) engineering submittal sheet
- Last verified date
- Jul 22, 2026
Bosch Climate 5000 Gen 4 18,000 BTU R-454B Max Performance (BMS500-AAU018-1AHWXD / BMS500-AAS018-1CSXHD) strengths
- Holds full 18,000 BTU of heat from 47F to 5F, rated to -22F - excellent sustained cold-climate output.
- HSPF2 11 - strong seasonal heating; Bosch support and 10/10 warranty.
Bosch Climate 5000 Gen 4 18,000 BTU R-454B Max Performance (BMS500-AAU018-1AHWXD / BMS500-AAS018-1CSXHD) weaknesses
- Lower cooling efficiency than the regular 18k (SEER2 21.4 vs 23.5) - you buy this for heating, not seasonal cooling numbers.
- Premium price; professional install; no confirmed online price.
Bosch Climate 5000 Gen 4 18,000 BTU R-454B Max Performance (BMS500-AAU018-1AHWXD / BMS500-AAS018-1CSXHD) climate suitability
- Minimum heating ambient
- -22 FVerified - manufacturer technical document
- Rated heating at 5F
- 18,000 BTU/hVerified - AHRI directory
- Rated heating at 17F
- 18,000 BTU/hVerified - AHRI directory
- Rated heating at 47F
- 18,000 BTU/hVerified - AHRI directory
Bosch Climate 5000 Gen 4 18,000 BTU R-454B Max Performance (BMS500-AAU018-1AHWXD / BMS500-AAS018-1CSXHD) electrical requirements
- Voltage
- 230 VVerified - manufacturer technical document
- Voltage range
- 208/230VVerified - manufacturer technical document
- Phase
- 1Verified - manufacturer technical document
- Frequency
- 60 HzVerified - manufacturer technical document
- MCA
- 19 AVerified - manufacturer technical document
- Breaker needed
- not published
- Maximum breaker size
- 20 AVerified - manufacturer technical document
- Maximum fuse size
- 20 AVerified - manufacturer technical document
- Maximum cooling current
- not published
- Maximum heating current
- not published
- Manufacturer wire notes
- not published
Bosch Climate 5000 Gen 4 18,000 BTU R-454B Max Performance (BMS500-AAU018-1AHWXD / BMS500-AAS018-1CSXHD) installation considerations
- Liquid line
- 1/4 inVerified - manufacturer technical document
- Suction line
- 1/2 inVerified - manufacturer technical document
- Precharged length
- 24.6 ftVerified - manufacturer technical document
- Included line-set length
- Bosch submittals publish field piping sizes, precharged refrigerant length, and accessory line sets, but do not specify an included line set for these professional-install systems.
- Maximum line-set length
- 98.4 ftVerified - manufacturer technical document
- Max line set per indoor
- not published
- Max height between indoor units
- not published
- Indoor dimensions
- 38.0 x 9.8 x 12.56 inVerified - manufacturer technical document
- Outdoor dimensions
- 35.04 x 13.46 x 26.5 inVerified - manufacturer technical document
- Indoor weight
- 27.34 lbVerified - manufacturer technical document
- Outdoor weight
- 99.87 lbVerified - manufacturer technical document
- Drain size
- not published
Bosch Climate 5000 Gen 4 18,000 BTU R-454B Max Performance (BMS500-AAU018-1AHWXD / BMS500-AAS018-1CSXHD) related systems and guides
- More Bosch systems
- Bosch Climate 5000 Gen 4 18,000 BTU R-454B Regular (BMS500-AAU018-1AHWXD / BMS500-AAS018-1CSXRD)
- Bosch Climate 5000 Gen 4 12,000 BTU R-454B 115V Regular (BMS500-AAS012-0AHWXD / BMS500-AAS012-0CSXRD)
- Bosch Climate 5000 Gen 4 12,000 BTU R-454B Max Performance (BMS500-AAU012-1AHWXD / BMS500-AAS012-1CSXHD)
- Bosch Climate 5000 Gen 4 12,000 BTU R-454B Regular (BMS500-AAU012-1AHWXD / BMS500-AAS012-1CSXRD)
- Buying guide
- Single vs multi-zone
- Cold-weather performance
Frequently asked questions
- Can I install the Bosch Climate 5000 Gen 4 18,000 BTU R-454B Max Performance (BMS500-AAU018-1AHWXD / BMS500-AAS018-1CSXHD) myself, or do I need a pro?
- Bosch Climate 5000 Gen 4 18,000 BTU R-454B Max Performance (BMS500-AAU018-1AHWXD / BMS500-AAS018-1CSXHD) 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 18,000 BTU R-454B Max Performance (BMS500-AAU018-1AHWXD / BMS500-AAS018-1CSXHD) keep heating in a cold winter?
- The manufacturer publishes 18,000 BTU/h of heating output at 5F. Rated heating operation extends down to -22 F. 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 Bosch Climate 5000 Gen 4 18,000 BTU R-454B Max Performance (BMS500-AAU018-1AHWXD / BMS500-AAS018-1CSXHD) need?
- Published electrical requirements: 230 V voltage, 19 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 is 98.4 ft, and the included line set comes pre-charged for 24.6 ft. 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 Bosch Climate 5000 Gen 4 18,000 BTU R-454B Max Performance (BMS500-AAU018-1AHWXD / BMS500-AAS018-1CSXHD) carry?
- The manufacturer publishes 10 years parts coverage and 10 years compressor coverage. Registration requirements and proof of qualified installation commonly affect coverage, so read the warranty terms before install day.
Bosch Climate 5000 Gen 4 18,000 BTU R-454B Max Performance (BMS500-AAU018-1AHWXD / BMS500-AAS018-1CSXHD) data sources
- Bosch Thermotechnology Corp.: BMS500-AAU018-1AHWXD & BMS500-AAS018-1CSXHD Bosch Climate 5000 Gen 4 submittalVerified - manufacturer technical document
Covers Frequency, electrical_spec.indoor_mca_amps, Maximum breaker size, Maximum fuse size, Minimum circuit ampacity, Phase and more
- AHRI Directory: AHRI public directory record 215223286Verified - AHRI directory
Covers AHRI certification number, Rated cooling capacity, COP at 5F, EER2, Rated heating capacity, HSPF2 (Region 4) and more
- ENERGY STAR Certified Air-Source Heat Pumps Directory: ENERGY STAR record 3554542 for BMS500-AAS018-1CSXHD / BMS500-AAU018-1AHWXDVerified - Energy Star listing
Covers Energy Star status
- Bosch Thermotechnology Corp.: Climate 5000 Ductless System Mini-Split Heat Pump (R-454B Version) manufacturer pageVerified - manufacturer product page
Covers Compressor warranty, Parts warranty, Warranty notes
Bosch Climate 5000 Gen 4 18,000 BTU R-454B Max Performance (BMS500-AAU018-1AHWXD / BMS500-AAS018-1CSXHD) last updated
Jul 22, 2026