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MRCOOL / DIY 5th Gen Multi-Zone

MRCOOL DIY 5th Gen 55k 6-Zone Mini-Split

Certified capacity
Varies by indoor-unit combination
SEER2
Varies by indoor-unit combination
Heating floor
-22 F[4]
Voltage
208/230V[1]
Install path
DIY install

The DIY 6-Zone 55k is the largest and coldest-rated condenser in MRCOOL's self-install multi-zone line: up to six heads, 55,000 BTU nominal, and - uniquely in this family - rated to operate down to -22F rather than -13F. It is the pick when a large home needs both maximum zones and the deepest documented cold-weather operation.

6 zonesDIY installCurrent

Refrigerant generation

R-454B - current-generation refrigerant

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Error Codes
MRCOOL DIY 5th Gen Multi-Zone 55k 6-zone outdoor condenser

Image: MRCOOL

Data completeness: 97%
Last sourced
Aug 17, 2026

SplitAtlas score

not yet rated - data incomplete

Methodology
  • scored 2 of 9 applicable categories, need at least 5

Key ratings

Rated cooling

Varies by indoor-unit combination

Rated heating

Varies by indoor-unit combination

Best-fit use cases

A large home in a genuinely cold climate that needs many zones and the deepest documented low-temperature operation from a single outdoor unit - the case where the -22F rating, not efficiency numbers, drives the choice.

Buyer review snapshot

Install difficulty

DIY multi-zone with planning load
  • Electrical: 208/230V; MCA 43 A; breaker/fuse 45 A.
  • Line set: Quick-connect line connections; max 221 ft.
  • 6-zone condenser; indoor-head matching and branch layout are part of the job.

Availability and price context

  • Last seen at HVACDirect on Jul 20, 2026: $3,809.00. Open the listing for today's price.
  • Sold at Amazon. Open the listing for today's price and stock.

Source date

Model data sourced
Aug 17, 2026
Page reviewed
Jul 20, 2026
Source-backed records
5
Newest source retrieved
Aug 17, 2026

Review methodology

Strengths

  • The deepest cold rating in the DIY multi-zone family: operation documented to -22F, versus -13F on every smaller sibling.
  • Highest capacity here - up to six zones, 55,000 BTU nominal, from one condenser.
  • DIY Quick Connect line sets; self-install-friendly 5/7-year warranty.
  • R-454B.

Weaknesses

  • No certified combination efficiency rating (multi-zone; see the page).
  • 43 A minimum circuit ampacity - the heaviest electrical load in the family; panel capacity must be confirmed.
  • A six-zone install is a major undertaking - most owners will hire the labor even on this DIY-capable unit.
  • Part-load efficiency penalty is real when a large home runs only a zone or two off a 55k compressor.
  • Size to the connectable-capacity limit, not the sum of the rooms.

Climate suitability

Minimum heating ambient
-22 F[4]
Certified heating at 5F
Varies by indoor-unit combination
Rated heating at 17F
Varies by indoor-unit combination
Rated heating at 47F
Varies by indoor-unit combination

Specifications

Show
Manufacturer
MRCOOL
Brand
MRCOOL
Product line
DIY 5th Gen Multi-Zone
Model number
DIY-MULTI6-55HP230D-O
Indoor unit model
Depends on the indoor units you choose
Outdoor unit model
DIY-MULTI6-55HP230D-O
Number of zones
6
Max indoor units
6 units[1]
Rated cooling capacity
Varies by indoor-unit combination
Rated heating capacity
Varies by indoor-unit combination
Voltage
208/230V[1]
MCA
43 A[1]
Maximum fuse or breaker size
45 A[1]
Breaker needed
not published
SEER2
Varies by indoor-unit combination
EER2
Varies by indoor-unit combination
HSPF2 (Region 4)
Varies by indoor-unit combination
HSPF2 (Region 5)
Varies by indoor-unit combination
COP
not published
COP at 47F
not published
COP at 5F
not published
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
64 dBA[1]
Indoor weight
Depends on the indoor units you choose
Outdoor weight
245.81 lb[1]
Refrigerant
R-454B[1]
Refrigerant charge
151.68 oz[1]
Manufacturer coverage
not published
Line-set size
1/4 in liquid / (3/8 x4), (1/2 x2) suction
Included line-set length
Depends on the indoor units you choose
Maximum line-set length
221 ft[4]
Max line set per indoor
75 ft[4]
Maximum elevation difference
33 ft[4]
Max height between indoor units
24 ft[4]
Wi-Fi support
Depends on the indoor units you choose
Energy Star status
not published
AHRI certification number
Varies by indoor-unit combination
Warranty
not published
Install path
DIY install
Retail price
last seen at HVACDirect on Jul 20, 2026: $3,809.00
Available retailers
HVACDirect, Amazon
Manual links
AHRI certificate for DIY-MULTI6-55HP230D-O, MRCOOL DIY Series Multi-Zone Mini-Split System Installation & Owner's Manual, MRCOOL R-454B Compatibility, MRCOOL DIY 5th Gen Multi-Zone 55k 6-Zone Outdoor Unit MRCOOL support article, MRCOOL DIY 5th Gen Multi-Zone brochure
Specification sheet
MRCOOL DIY 5th Gen Multi-Zone brochure
Last sourced date
Aug 17, 2026

Retail purchase context

Some retailer links may earn us a commission at no extra cost; paid relationships never change scores or recommendations. Affiliate disclosure

Paid link

Check price at HVACDirect

Reference-only price

Last seen at HVACDirect on Jul 20, 2026: $3,809

Check price on Amazon

Compatible indoor units

This is an outdoor unit. You choose its indoor heads separately - up to the maximum this condenser supports - and you can mix room sizes and styles across the zones. The models below are the heads this unit is documented to pair with.

  • Multi-position air handlers

    24k, 36k

    Model numbers
    • 24k: DIY-24-HP-MUAH-230D25-O
    • 36k: DIY-36-HP-MUAH-230D25-O

  • One-way ceiling cassettes

    6k, 9k, 12k, 18k

    Model numbers
    • 6k: DIYCASSETTE06HP-230D25-O
    • 9k: DIYCASSETTE09HP-230D25-O
    • 12k: DIYCASSETTE12HP-230D25-O
    • 18k: DIYCASSETTE18HP-230D25-O

  • Wall-mounteds

    6k, 9k, 12k, 18k, 24k, 36k

    Model numbers
    • 6k: DIY-06-HP-WMAH-230D25-O
    • 9k: DIY-09-HP-WMAH-230D25-O
    • 12k: DIY-12-HP-WMAH-230D25-O
    • 18k: DIY-18-HP-WMAH-230D25-O
    • 24k: DIY-24-HP-WMAH-230D25-O
    • 36k: DIY-36-HP-WMAH-230D25-O

Sizing note: do not just add up the rooms. Multi-zone condensers have a maximum total connected capacity, and connecting more head capacity than the unit is rated for is a common installer mistake that hurts efficiency and comfort. Match total head capacity to the condenser's rating.

Parts and filters

Fits MRCOOL DIY 5th Gen Multi-Zone 55k 6-Zone Outdoor Unit. Part numbers and fit notes identify compatibility only; no manufacturer endorsement is implied.

smart-thermostat

MRCOOL Smart Wi-Fi Mini Stat

Fits
MRCOOL DIY 5th Gen Multi-Zone 55k 6-Zone Outdoor Unit
OEM part number
MST05
Fit note
Fits DIY-MULTI6-55HP230D-O. Use with compatible connected MRCOOL mini-split indoor heads where a wall-mounted smart control is desired. HVACDirect was verified as a live exact-part page on 2026-08-01; verify each indoor head before ordering.
Source
MRCOOL Mini-Stats, MRCOOL Mini Stats, page article (MST05)

quick-connect-line-set

25 ft Quick Connect precharged line set - 1/4 x 3/8

Fits
MRCOOL DIY 5th Gen Multi-Zone 55k 6-Zone Outdoor Unit
OEM part number
DIY25-1438-O
Fit note
Fits DIY-MULTI6-55HP230D-O. Match line-set size to the connected indoor head and port. Use this 1/4 x 3/8 R-454B Quick Connect line set for compatible 6k, 9k, and 12k MRCOOL DIY indoor heads. HVACDirect was verified as a live exact-part page on 2026-08-01.
Source
MRCOOL 5th Gen R-454B DIY Line Set 1/4 - 3/8, DIY 5th Gen 6k, 9k & 12k, page article (DIY25-1438-O)

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Paid link

Check price at HVACDirect

quick-connect-line-set

25 ft Quick Connect precharged line set - 1/4 x 1/2

Fits
MRCOOL DIY 5th Gen Multi-Zone 55k 6-Zone Outdoor Unit
OEM part number
DIY25-1412-O
Fit note
Fits DIY-MULTI6-55HP230D-O. Match line-set size to the connected indoor head and port. Use this 1/4 x 1/2 R-454B Quick Connect line set for compatible MRCOOL DIY 18k indoor heads. HVACDirect was verified as a live exact-part page on 2026-08-01.
Source
MRCOOL 5th Gen R-454B DIY Line Set 1/4 - 1/2, DIY 5th Gen 9k, 12k & 18k, page article (DIY25-1412-O)

Some retailer links may earn us a commission at no extra cost; paid relationships never change scores or recommendations. Affiliate disclosure

Paid link

Check price at HVACDirect

quick-connect-line-set

25 ft Quick Connect precharged line set - 3/8 x 5/8

Fits
MRCOOL DIY 5th Gen Multi-Zone 55k 6-Zone Outdoor Unit
OEM part number
DIY25-3858-O
Fit note
Fits DIY-MULTI6-55HP230D-O. Match line-set size to the connected indoor head and port. Use this 3/8 x 5/8 R-454B Quick Connect line set for compatible MRCOOL DIY 24k and 36k indoor heads. HVACDirect was verified as a live exact-part page on 2026-08-01.
Source
MRCOOL 5th Gen R-454 DIY Line Set 3/8 - 5/8, DIY 5th Gen 24k & 36k, page article (DIY25-3858-O)

Some retailer links may earn us a commission at no extra cost; paid relationships never change scores or recommendations. Affiliate disclosure

Paid link

Check price at HVACDirect
Replacement Parts & Filters

Electrical requirements

Show
Voltage
not published
Voltage range
208/230V[1]
Phase
1[1]
Frequency
60 Hz[1]
MCA
43 A[1]
Breaker needed
not published
Maximum breaker size
not published
Maximum fuse size
45 A[1]
Maximum cooling current
not published
Maximum heating current
not published
Manufacturer wire notes
not published

Installation considerations

Show
Liquid line
1/4 in[3]
Suction line
(3/8 x4), (1/2 x2)[3]
Line connection type
Quick-connect line connections[2]
Precharged length
not published
Included line-set length
Depends on the indoor units you choose
Maximum line-set length
221 ft[4]
Max line set per indoor
75 ft[4]
Max height between indoor units
24 ft[4]
Indoor dimensions
Depends on the indoor units you choose
Outdoor dimensions
37.48 x 16.34 x 52.48 in[1]
Indoor weight
Depends on the indoor units you choose
Outdoor weight
245.81 lb[1]
Drain size
not published

Related systems and guides

Frequently asked questions

Can I install the MRCOOL DIY 5th Gen Multi-Zone 55k 6-Zone Outdoor Unit myself, or do I need a pro?
MRCOOL DIY 5th Gen Multi-Zone 55k 6-Zone Outdoor Unit is sold as a DIY-installable system. The electrical circuit is the part that is not DIY: plan on a licensed electrician for the dedicated circuit, and check whether your local permit office requires a permit for the install.
Will the MRCOOL DIY 5th Gen Multi-Zone 55k 6-Zone Outdoor Unit keep heating in a cold winter?
Rated heating operation extends down to -22 F. Match that published heating floor against your climate's design temperature - below the low-ambient rating, output can fall off or the system can pause to protect itself.
What electrical circuit does the MRCOOL DIY 5th Gen Multi-Zone 55k 6-Zone Outdoor Unit need?
Published electrical requirements: 208/230V voltage, 43 A minimum circuit ampacity, and 45 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 75 ft. The combined piping limit across all heads is 221 ft. Measure the planned routing before ordering.

Data sources

Show
  1. MRCOOL: MRCOOL DIY 5th Gen Multi-Zone brochureSourced - manufacturer technical document

    Covers Frequency, Maximum fuse size, Minimum circuit ampacity, Phase, Voltage range, Outdoor dimensions and more

  2. MRCOOL: MRCOOL DIY Series Multi-Zone Mini-Split System Installation & Owner's ManualSourced - manufacturer technical document

    Covers Line connection type

  3. MRCOOL Support: MRCOOL DIY 5th Gen Multi-Zone 55k 6-Zone Outdoor Unit MRCOOL support articleSourced - manufacturer product page

    Covers Liquid line size, Suction line size

  4. MRCOOL: MRCOOL DIY Series Multi-Zone Mini-Split System Installation & Owner's ManualSourced - manufacturer technical document

    Covers Maximum elevation difference, Maximum line-set length, Max height between indoor units, Max line set per indoor, Minimum outdoor cooling temperature, Minimum outdoor heating temperature and more

  5. MRCOOL: MRCOOL 5th Generation DIY Series Limited WarrantySourced - manufacturer technical document

    Covers Legacy compressor warranty value, Legacy warranty value

Last updated

Jul 20, 2026