SplitAtlas

Mitsubishi Electric / M-Series WX

Mitsubishi M-Series WX 12k R-454B 208/230V Mini-Split

Certified capacity
12,000 BTU/h[3]
SEER2
18 SEER2[3]
Heating floor
5 F[4]
Voltage
208/230V[1]
Install path
Professional install

The M-Series WX 12k is the 1-ton builder-grade unit: SEER2 18, EER2 9, HSPF2 8.5, on R-454B refrigerant with 12,200 BTU of heat at 47F. It is a basic, low-cost current Mitsubishi for a larger room where budget drives the decision.

1 zoneProfessional installCurrent

Refrigerant generation

R-454B - current-generation refrigerant

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Error Codes
Mitsubishi Electric M-Series WX 12,000 BTU R-454B 208/230V (MSZ-WX12NL / MUZ-WX12NL)

Image: Mitsubishi Electric

Data completeness: 95%
Last sourced
Jul 23, 2026

SplitAtlas score

7.6 / 10

Methodology
Cooling efficiencyBottom quartile

(18.0 SEER2) among 12k systems

Heating efficiencyBottom quartile

(8.5 HSPF2) among 12k systems

Cold-weather performanceBottom quartile

(17F certified capacity: 61.5% of the 47F rating; 5 F heating floor) among 12k systems

NoiseAbove average

(22 dBA indoor min / 51 dBA outdoor) among 12k systems

WarrantyTop quartile

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

Feature setBottom quartile

(1 verified feature) across the catalogue

Documentation & partsTop quartile

(9 manuals; spec sheet; parts channel) 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.

    Get a quote

Key ratings

Rated cooling

12,000BTU/h[3]

Rated heating

12,200BTU/h[3]

Buyer review snapshot

Install difficulty

Professional install
  • Electrical: 208/230V; MCA 10 A; breaker/fuse 15 A.
  • Line set: connection type not sourced; precharged 25 ft; max 65 ft.

Alternatives

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 23, 2026
Page reviewed
Jul 23, 2026
Source-backed records
5
Newest source retrieved
Jul 23, 2026

Warranty tiers

Base
5 yr parts / 7 yr compressor - licensed HVAC contractor installation
Registered
10 yr parts / 10 yr compressor - owner-occupied residence registered within 90 days of installation
Program
12 yr parts / 12 yr compressor - owner-occupied residence installed and registered by a Diamond Contractor within 90 days

The score uses Registered. Additional published terms are shown for reference and not counted in the score.

Review methodology

Model context

Mitsubishi dealer channel
Mitsubishi Electric equipment is sold through its dealer network; installed price depends on the local contractor.

Strengths

  • Low entry price with current R-454B refrigerant.
  • 12,200 BTU rated heat at 47F for a 1-ton space.

Weaknesses

  • EER2 9 / HSPF2 8.5 - basic efficiency, no published 5F rating.
  • Professional dealer installation required; the HX or GX 12k are notably more efficient.

Climate suitability

Minimum heating ambient
5 F[4]
Certified heating at 5F
not published
Maximum heating at 5F (manufacturer)
6,780 BTU/h[2]
Rated heating at 17F
7,500 BTU/h[3]
Rated heating at 47F
12,200 BTU/h[3]

Specifications

Show
Manufacturer
Mitsubishi Electric
Brand
Mitsubishi Electric
Product line
M-Series WX
Model number
MSZ-WX12NL-U1 indoor / MUZ-WX12NL-U1 outdoor
Indoor unit model
MSZ-WX12NL-U1
Outdoor unit model
MUZ-WX12NL-U1
Number of zones
1
Max indoor units
not published
Rated cooling capacity
12,000 BTU/h[3]
Rated heating capacity
12,200 BTU/h[3]
Voltage
208/230V[1]
MCA
10 A[2]
Maximum fuse or breaker size
15 A[2]
Breaker needed
not published
SEER2
18 SEER2[3]
EER2
9 EER2[3]
HSPF2 (Region 4)
8.5 HSPF2[3]
HSPF2 (Region 5)
not published
COP
not published
COP at 47F
3.28 COP[2]
COP at 5F
not published
Minimum outdoor heating temperature
5 F[4]
Minimum outdoor cooling temperature
32 F[4]
Maximum outdoor temperature
115 F[4]
Indoor noise range
cooling 22 , 30 , 37 , 45; heating 22 , 30 , 37 , 43[2]
Outdoor noise rating
51 dBA[2]
Indoor weight
20 lb[2]
Outdoor weight
65 lb[2]
Refrigerant
R-454B[3]
Refrigerant charge
not published
Manufacturer coverage
not published
Line-set size
1/4 in liquid / 3/8 in suction
Included line-set length
Mitsubishi submittals publish line-size and maximum/precharged piping data; the installer supplies the line set.
Maximum line-set length
65 ft[2]
Max line set per indoor
not published
Maximum elevation difference
40 ft[2]
Max height between indoor units
not published
Wi-Fi support
not published
Energy Star status
Not ENERGY STAR certified[3]
AHRI certification number
216626282[3]
Warranty
Base: 5 yr parts / 7 yr compressor (licensed HVAC contractor installation); Registered: 10 yr parts / 10 yr compressor (owner-occupied residence registered within 90 days of installation); Program: 12 yr parts / 12 yr compressor (owner-occupied residence installed and registered by a Diamond Contractor within 90 days). Score uses Registered. Additional published terms are shown for reference and not counted in the score.. Standard residential M-Series warranty is 5 years parts and 7 years compressor from installation by a licensed HVAC contractor. Enhanced residential terms are 10 years parts and compressor for an owner-occupied residence registered within 90 days of installation, and 12 years parts and compressor when installed in an owner-occupied residence by a Diamond Contractor and registered by that Diamond Contractor within 90 days.
Install path
Professional install
Retail price
Installed quote only
Available retailers
not published
Manual links
AHRI certificate 216626282, AHRI public detail 216626282, ENERGY STAR exact row for AHRI 216626282, M-Series WX Mitsubishi Comfort product page, M-Series WX Mitsubishi Comfort product page, MitsubishiPro product record MUZ-WX12NL-U1, MSZ-WX12NL & MUZ-WX12NL Mitsubishi Electric submittal, METUS Residential M-Series, P-Series and SMART MULTI Limited Warranty Statement
Specification sheet
MSZ-WX12NL & MUZ-WX12NL Mitsubishi Electric submittal
Last sourced date
Jul 23, 2026

Parts and filters

Fits Mitsubishi Electric M-Series WX 12,000 BTU R-454B 208/230V (MSZ-WX12NL / MUZ-WX12NL). Part numbers and fit notes identify compatibility only; no manufacturer endorsement is implied.

filter-anti-allergy

Mitsubishi electro static anti-allergy enzyme filter

Fits
Mitsubishi Electric M-Series WX 12,000 BTU R-454B 208/230V (MSZ-WX12NL / MUZ-WX12NL)
OEM part number
MAC-2320FT-E
Filter care
Replace every year; vacuum every 3 months in between; if dirt remains, soak and rinse in lukewarm water, then shade-dry.
Fit note
Fits MSZ-WX12NL / MUZ-WX12NL. Manufacturer documentation publishes this OEM part number for this model family. No live HVACDirect exact-part offer was found; source through an authorized Mitsubishi Electric dealer with the model and serial number.
Source
Mitsubishi Electric MSZ-WX09NL / MUZ-WX09NL Submittal, INDOOR UNIT ACCESSORIES: MSZ-WX09NL, page p. 4 (Electro Static Anti-allergy Enzyme Filter MAC-2320FT-E)

filter-microparticle

Mitsubishi microparticle filter

Fits
Mitsubishi Electric M-Series WX 12,000 BTU R-454B 208/230V (MSZ-WX12NL / MUZ-WX12NL)
OEM part number
MAC-EMF515FT-E
Filter care
Replace every 3 years; vacuum only every 3 months in between; do not wash with water.
Fit note
Fits MSZ-WX12NL / MUZ-WX12NL. Manufacturer documentation publishes this OEM part number for this model family. No live HVACDirect exact-part offer was found; source through an authorized Mitsubishi Electric dealer with the model and serial number.
Source
Mitsubishi Electric MSZ-WX09NL / MUZ-WX09NL Submittal, INDOOR UNIT ACCESSORIES: MSZ-WX09NL, page p. 4 (Microparticle Filter MAC-EMF515FT-E)

smart-controller-module

Mitsubishi Wireless Interface 2

Fits
Mitsubishi Electric M-Series WX 12,000 BTU R-454B 208/230V (MSZ-WX12NL / MUZ-WX12NL)
OEM part number
PAC-USWHS002-WF-2
Fit note
Fits MSZ-WX12NL / MUZ-WX12NL. Manufacturer documentation publishes this OEM part number for this model family. HVACDirect was verified as a live exact-part page on 2026-08-01.
Source
Mitsubishi Electric MSZ-WX09NL / MUZ-WX09NL Submittal, INDOOR UNIT ACCESSORIES: MSZ-WX09NL, page p. 4 (Wireless Interface 2 for Comfrot app PAC-USWHS002-WF-2)

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

control-interface

Mitsubishi M-Net I/O Control Interface for M-Series

Fits
Mitsubishi Electric M-Series WX 12,000 BTU R-454B 208/230V (MSZ-WX12NL / MUZ-WX12NL)
OEM part number
MAC-334IF-E
Fit note
Fits MSZ-WX12NL / MUZ-WX12NL. Manufacturer documentation publishes this OEM part number for this model family. HVACDirect was verified as a live exact-part page on 2026-08-01.
Source
Mitsubishi Electric MSZ-WX09NL / MUZ-WX09NL Submittal, INDOOR UNIT ACCESSORIES: MSZ-WX09NL, page p. 4 (M-Net I/O Control Interface for M-Series <sup>2</sup> MAC-334IF-E)

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

thermostat-interface

Mitsubishi thermostat interface for third-party thermostats

Fits
Mitsubishi Electric M-Series WX 12,000 BTU R-454B 208/230V (MSZ-WX12NL / MUZ-WX12NL)
OEM part number
PAC-US445CN-1
Fit note
Fits MSZ-WX12NL / MUZ-WX12NL. Manufacturer documentation publishes this OEM part number for this model family. HVACDirect was verified as a live exact-part page on 2026-08-01.
Source
Mitsubishi Electric MSZ-WX09NL / MUZ-WX09NL Submittal, INDOOR UNIT ACCESSORIES: MSZ-WX09NL, page p. 4 (Thermostat Interface for 3rd Party Thermostats PAC-US445CN-1)

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

wireless-remote-controller

Mitsubishi RedLINK wireless remote controller

Fits
Mitsubishi Electric M-Series WX 12,000 BTU R-454B 208/230V (MSZ-WX12NL / MUZ-WX12NL)
OEM part number
MHK2
Fit note
Fits MSZ-WX12NL / MUZ-WX12NL. Manufacturer documentation publishes this OEM part number for this model family. HVACDirect was verified as a live exact-part page on 2026-08-01.
Source
Mitsubishi Electric MSZ-WX09NL / MUZ-WX09NL Submittal, INDOOR UNIT ACCESSORIES: MSZ-WX09NL, page p. 4 (Wireless RedLINK™ Remote Controller MHK2)

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
Find this model's filterReplacement Parts & Filters

Electrical requirements

Show
Voltage
not published
Voltage range
208/230V[1]
Phase
1[1]
Frequency
60 Hz[1]
MCA
10 A[2]
Breaker needed
not published
Maximum breaker size
not published
Maximum fuse size
15 A[2]
Maximum cooling current
not published
Maximum heating current
not published
Manufacturer wire notes
14 AWG indoor-outdoor[2]

Installation considerations

Show
Liquid line
1/4 in[2]
Suction line
3/8 in[2]
Line connection type
not published
Precharged length
25 ft[2]
Included line-set length
Mitsubishi submittals publish line-size and maximum/precharged piping data; the installer supplies the line set.
Maximum line-set length
65 ft[2]
Max line set per indoor
not published
Max height between indoor units
not published
Indoor dimensions
33 x 9 x 11-1/16 in[2]
Outdoor dimensions
31-1/2 x 11-1/4 x 21-5/8 in[2]
Indoor weight
20 lb[2]
Outdoor weight
65 lb[2]
Drain size
5/8 in[2]

Related systems and guides

Frequently asked questions

Can I install the Mitsubishi Electric M-Series WX 12,000 BTU R-454B 208/230V (MSZ-WX12NL / MUZ-WX12NL) myself, or do I need a pro?
Mitsubishi Electric M-Series WX 12,000 BTU R-454B 208/230V (MSZ-WX12NL / MUZ-WX12NL) 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 Mitsubishi Electric M-Series WX 12,000 BTU R-454B 208/230V (MSZ-WX12NL / MUZ-WX12NL) keep heating in a cold winter?
Rated heating operation extends down to 5 F. Certified heating efficiency is 8.5 HSPF2. 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 Mitsubishi Electric M-Series WX 12,000 BTU R-454B 208/230V (MSZ-WX12NL / MUZ-WX12NL) need?
Published electrical requirements: 208/230V voltage, 10 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 65 ft. The outdoor unit's factory charge covers up to 25 ft of line; longer runs need added refrigerant. Measure the planned routing before ordering.
What warranty does the Mitsubishi Electric M-Series WX 12,000 BTU R-454B 208/230V (MSZ-WX12NL / MUZ-WX12NL) carry?
The manufacturer publishes these warranty tiers: Base: 5 yr parts / 7 yr compressor (licensed HVAC contractor installation); Registered: 10 yr parts / 10 yr compressor (owner-occupied residence registered within 90 days of installation); Program: 12 yr parts / 12 yr compressor (owner-occupied residence installed and registered by a Diamond Contractor within 90 days). 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

Show
  1. Mitsubishi Electric Trane HVAC US LLC: MitsubishiPro product record MUZ-WX12NL-U1Sourced - manufacturer product page

    Covers Frequency, Phase, Voltage range, system.lifecycle_status

  2. Mitsubishi Electric Trane HVAC US LLC: MSZ-WX12NL & MUZ-WX12NL Mitsubishi Electric M-Series WX submittalSourced - manufacturer technical document

    Covers electrical_spec.guaranteed_voltage_range, electrical_spec.indoor_mca_amps, Maximum fuse size, Minimum circuit ampacity, Manufacturer wire notes, Drain size and more

  3. Air-Conditioning, Heating, and Refrigeration Institute: AHRI public detail 216626282 for MSZ-WX12NL / MUZ-WX12NLSourced - AHRI directory

    Covers AHRI certification number, performance_spec.cold_climate_designation, Rated cooling capacity, EER2, Energy Star status, Rated heating capacity and more

  4. Mitsubishi Electric Trane HVAC US LLC: MSZ-WX12NL & MUZ-WX12NL Mitsubishi Electric M-Series WX submittalSourced - manufacturer technical document

    Covers Minimum outdoor cooling temperature, Minimum outdoor heating temperature, Maximum outdoor temperature

  5. Mitsubishi Electric Trane HVAC US LLC: METUS Residential M-Series, P-Series and SMART MULTI Limited Warranty StatementSourced - secondary source

    Covers Additional published compressor warranty, Additional published warranty conditions, Additional published parts warranty, Legacy compressor warranty value, Legacy warranty value, Registered compressor warranty and more

Last updated

Jul 23, 2026