SplitAtlas

MRCOOL / DIY 5th Gen Hyper Heat

MRCOOL DIY 5th Gen Hyper Heat 18k Hyper 230V Mini-Split

Certified capacity
18,000 BTU/h[4]
SEER2
21.2 SEER2[4]
Heating floor
-22 F[5]
Voltage
208/230V[1]
Install path
DIY install

The MRCOOL DIY Hyper Heat 18k is a DIY cold-climate model: it holds its full 18,000 BTU/h of rated heating all the way down to 5F and operates to -22F, at an HSPF2 of 11 - performance that usually comes from a pro-installed Hyper-Heating system, in a unit you can install yourself with Quick Connect line sets.

1 zoneDIY installCurrent

Refrigerant generation

R-454B - current-generation refrigerant

Paid link

$3,173 / Fresh price - checked Jul 27, 2026

$3,173 at HVACDirect

Need this installed?

Get installation quotes
Error Codes
MRCOOL DIY 5th Gen Hyper Heat 18k mini-split indoor wall unit
MRCOOL DIY 5th Gen Hyper Heat 18k mini-split indoor wall unit
MRCOOL DIY 5th Gen Hyper Heat 18k mini-split outdoor condenser

Image: HVACDirect

Data completeness: 98%
Last sourced
Aug 17, 2026

SplitAtlas score

8.6 / 10

Methodology
Cooling efficiencyBelow average

(21.2 SEER2) among 18k systems

Heating efficiencyAbove average

(11.0 HSPF2) among 18k systems

Cold-weather performanceTop quartile

(5F certified capacity: 100% of the 47F rating; -22 F heating floor) among 18k systems

NoiseTop quartile

(20.5 dBA indoor min / 58 dBA outdoor) among 18k systems

WarrantyBelow average

(5 yr parts / 7 yr compressor) across the catalogue

Installation accessibilityAbove average

(DIY-marketed; 25 ft precharged; 25 ft included line set) across the catalogue

Price-to-performanceBottom quartile

($3,173 median retail) among 18k systems

Documentation & partsTop quartile

(8 manuals; spec sheet; parts channel) across the catalogue

Key ratings

Rated cooling

18,000BTU/h[4]

Rated heating

18,000BTU/h[4]

Best-fit use cases

A cold-climate home needing serious, self-installed heating for a larger room or open zone - where you want Hyper-Heating-class low-temperature output without booking a contractor, and 230V service is available.

Where this system ranks

Buyer review snapshot

Install difficulty

DIY install path, electrical work likely
  • Electrical: 208/230V; MCA 19 A; breaker/fuse 25 A.
  • Line set: Quick-connect line connections; precharged 25 ft; included 25 ft; max 75 ft.

Alternatives

Availability and price context

  • Listed price: $3,173.00 at HVACDirect, checked Jul 27, 2026. Open the listing for today's price and stock.

Source date

Model data sourced
Aug 17, 2026
Page reviewed
Jul 21, 2026
Source-backed records
8
Newest source retrieved
Aug 17, 2026

Warranty tiers

Base
5 yr parts / 7 yr compressor - standard coverage

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

Review methodology

Strengths

  • Publishes 18,000 BTU/h heating at 5F - full rated capacity maintained in deep cold, which most heat pumps cannot claim.
  • HSPF2 11 - high seasonal heating efficiency, and rated operation to -22F.
  • DIY-installable (pre-charged Quick Connect); 5-year parts / 7-year compressor warranty that does not disclaim self-installation.
  • R-454B refrigerant.

Weaknesses

  • 230V with a 19 A minimum circuit ampacity and 25 A max fuse - a real electrical load; confirm your panel before planning a DIY install.
  • SEER2 21.2 - cooling efficiency trails the 12k; this unit is tuned for heating, so mild-climate coolers gain little from it.
  • Highest price in the DIY single-zone line - you're paying for the cold-climate heating.

Climate suitability

Minimum heating ambient
-22 F[5]
Certified heating at 5F
18,000 BTU/h[4]
Rated heating at 17F
15,200 BTU/h[4]
Rated heating at 47F
18,000 BTU/h[4]

Specifications

Show
Manufacturer
MRCOOL
Brand
MRCOOL
Product line
DIY 5th Gen Hyper Heat
Model number
DIY-18-HP-WMAH-230D25-O indoor / DIYHH-18-HP-C-230D25-O outdoor
Indoor unit model
DIY-18-HP-WMAH-230D25-O
Outdoor unit model
DIYHH-18-HP-C-230D25-O
Number of zones
1
Max indoor units
not published
Rated cooling capacity
18,000 BTU/h[4]
Rated heating capacity
18,000 BTU/h[4]
Voltage
208/230V[1]
MCA
19 A[1]
Maximum fuse or breaker size
25 A[1]
Breaker needed
not published
SEER2
21.2 SEER2[4]
EER2
12.5 EER2[4]
HSPF2 (Region 4)
11 HSPF2[4]
HSPF2 (Region 5)
8.5 HSPF2[1]
COP
not published
COP at 47F
not published
COP at 5F
1.99 COP[4]
Minimum outdoor heating temperature
-22 F[5]
Minimum outdoor cooling temperature
-22 F[5]
Maximum outdoor temperature
122 F[5]
Indoor noise range
54.5 / 45 / 40 / 30.5 / 20.5 dB(A)[1]
Outdoor noise rating
58 dBA[1]
Indoor weight
35.49 lb[1]
Outdoor weight
99.87 lb[1]
Refrigerant
R-454B[1]
Refrigerant charge
52.21 oz[1]
Manufacturer coverage
800 sq ft[1]
Line-set size
1/4 in liquid / 1/2 in suction
Included line-set length
25 ft[1]
Maximum line-set length
75 ft[3]
Max line set per indoor
not published
Maximum elevation difference
not published
Max height between indoor units
not published
Wi-Fi support
supported[1]
Energy Star status
ENERGY STAR certified[4]
AHRI certification number
216032551[4]
Warranty
Base: 5 yr parts / 7 yr compressor (standard coverage). Score uses Base.. Standard 5-year parts plus 7-year compressor warranty.
Install path
DIY install
Retail price
$3,173.00
Available retailers
HVACDirect
Manual links
AHRI certificate 216032551 for DIYHH-18-HP-C-230D25-O / DIY-18-HP-WMAH-230D25-O, AHRI public directory details for MRCOOL DIY Hyper Heat wall-mount pairings, MRCOOL DIY Hyper Heat Series Single Zone Installation and Owner's Manual, DIY 5th Gen - R454B - 18K Hyper Heat BTU 230V Condenser w/ 25ft Install Kit, MRCOOL DIY Hyper Heat 5th Gen performance specs, HVACDirect product page DIYHH-18-HP-WM-230D25-O, MRCOOL DIY Hyper Heat 5th Gen brochure/specifications, MRCOOL 5th Generation DIY Series Limited Warranty
Specification sheet
MRCOOL DIY Hyper Heat 5th Gen brochure/specifications
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

$3,173 at HVACDirect

$3,173 / Fresh price - checked Jul 27, 2026

Parts and filters

Fits MRCOOL DIY Hyper Heat 5th Gen 18,000 BTU (230V). Part numbers and fit notes identify compatibility only; no manufacturer endorsement is implied.

filter-washable

Washable air filter

Fits
MRCOOL DIY Hyper Heat 5th Gen 18,000 BTU (230V)
Filter care
Washable. Clean and reuse. MRCOOL does not publish a calendar cleaning interval for the primary filter. Replace if damaged or no longer cleanable.
Fit note
Fits DIY-18-HP-WMAH-230D25-O / DIYHH-18-HP-C-230D25-O. The indoor filter is a cleanable service item. MRCOOL does not publish an orderable model-specific filter SKU in the service manual; source replacements through the installer, place of purchase, or MRCOOL authorized parts support at https://support.mrcool.com/hc/en-us/articles/28733842948884-Where-Can-I-Purchase-Parts-for-MRCOOL-Systems.
Source
MRCOOL DIY 5th Gen Service Manual, 4.5 Error Diagnosis Without Error Code - Remote Maintenance, page p. 46 (Dirty air filter ... Clean or replace)

remote-control

Remote control

Fits
MRCOOL DIY Hyper Heat 5th Gen 18,000 BTU (230V)
Fit note
Fits DIY-18-HP-WMAH-230D25-O / DIYHH-18-HP-C-230D25-O. MRCOOL does not publish an OEM part number for the remote; its authorized Mass HVAC store sells a 4th/5th Gen replacement.
Source
MRCOOL DIY 5th Gen Service Manual, 4.5 Remote Maintenance, page p. 46 (Replace the remote control)

smart-thermostat

MRCOOL Smart Wi-Fi Mini Stat

Fits
MRCOOL DIY Hyper Heat 5th Gen 18,000 BTU (230V)
OEM part number
MST05
Fit note
Fits DIY-18-HP-WMAH-230D25-O / DIYHH-18-HP-C-230D25-O. MRCOOL publishes MST05 for its mini-splits. HVACDirect lists MST04, a different part, so no HVACDirect link is shown. MRCOOL's authorized store also offers the MTSK02 Mini-Stat.
Source
MRCOOL Mini-Stats, MRCOOL Mini Stats, page article (MST05)

quick-connect-line-set

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

Fits
MRCOOL DIY Hyper Heat 5th Gen 18,000 BTU (230V)
OEM part number
DIY25-1412-O
Fit note
Fits DIY-18-HP-WMAH-230D25-O / DIYHH-18-HP-C-230D25-O. 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

display-board

Display board (service part)

Fits
MRCOOL DIY Hyper Heat 5th Gen 18,000 BTU (230V)
Fit note
Fits DIY-18-HP-WMAH-230D25-O / DIYHH-18-HP-C-230D25-O. The service manual identifies the display board as a replaceable diagnostic item, but does not publish a model-specific orderable SKU. Use model and serial through MRCOOL support or an authorized parts distributor.
Source
MRCOOL DIY 5th Gen Service Manual, 4.2 Error Display (Indoor Unit), page p. 36 (If the unit responds, the display board requires replacement.)

indoor-pcb

Indoor control board / PCB (service part)

Fits
MRCOOL DIY Hyper Heat 5th Gen 18,000 BTU (230V)
Fit note
Fits DIY-18-HP-WMAH-230D25-O / DIYHH-18-HP-C-230D25-O. The service manual identifies the indoor PCB as the replacement path when the unit does not respond to the remote, but does not publish a model-specific orderable SKU. Use model and serial through MRCOOL support or an authorized parts distributor.
Source
MRCOOL DIY 5th Gen Service Manual, 4.2 Error Display (Indoor Unit), page p. 36 (If the unit does not respond to the remote, the indoor PCB requires replacement.)

louver-motor

Louver stepping motor (service part)

Fits
MRCOOL DIY Hyper Heat 5th Gen 18,000 BTU (230V)
Fit note
Fits DIY-18-HP-WMAH-230D25-O / DIYHH-18-HP-C-230D25-O. The service manual calls for replacing the stepping motor when the horizontal louver will not move, but does not publish a model-specific orderable SKU. Use model and serial through MRCOOL support or an authorized parts distributor.
Source
MRCOOL DIY 5th Gen Service Manual, 4.5 Field Maintenance, page p. 50 (Replace the stepping motor)

air-cleaning-accessory

MRCOOL Cool Care kit (MMCK01)

Fits
MRCOOL DIY Hyper Heat 5th Gen 18,000 BTU (230V)
OEM part number
MMCK01
Fit note
Fits DIY-18-HP-WMAH-230D25-O / DIYHH-18-HP-C-230D25-O. MRCOOL lists the Cool Care kit (MMCK01) for this model; each six-month kit includes a replacement air-freshening filter. This accessory is separate from the washable primary filter.
Source
MMCK01 COOL Care Program Kit, Compatibility, page article (Each shipment includes ... a fresh air filter. Compatibility: MRCOOL DIY Mini Split System.)
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
19 A[1]
Breaker needed
not published
Maximum breaker size
not published
Maximum fuse size
25 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[1]
Suction line
1/2 in[1]
Line connection type
Quick-connect line connections[2]
Precharged length
25 ft[1]
Included line-set length
25 ft[1]
Maximum line-set length
75 ft[3]
Max line set per indoor
not published
Max height between indoor units
not published
Indoor dimensions
42.52 in W x 13.19 in H x 8.9 in D[1]
Outdoor dimensions
35.04 in W x 26.5 in H x 13.46 in D[1]
Indoor weight
35.49 lb[1]
Outdoor weight
99.87 lb[1]
Drain size
not published

Comparable models

MRCOOL DIY Hyper Heat vs Senville AURA (18,000 BTU, cold-climate)

Side-by-side comparison

MRCOOL DIY vs DIY Hyper Heat (18,000 BTU)

Side-by-side comparison

Related systems and guides

Frequently asked questions

Can I install the MRCOOL DIY Hyper Heat 5th Gen 18,000 BTU (230V) myself, or do I need a pro?
MRCOOL DIY Hyper Heat 5th Gen 18,000 BTU (230V) is sold as a DIY-installable system with an included 25 ft line set, so a standard install needs no vacuum pump or gauges. EPA's Section 608 guidance says connecting pre-charged lines still requires technician certification. 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 Hyper Heat 5th Gen 18,000 BTU (230V) keep heating in a cold winter?
The AHRI/ENERGY STAR certification lists 18,000 BTU/h of heating capacity 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 MRCOOL DIY Hyper Heat 5th Gen 18,000 BTU (230V) need?
Published electrical requirements: 208/230V voltage, 19 A minimum circuit ampacity, and 25 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 75 ft. The outdoor unit's factory charge covers up to 25 ft of line; longer runs need added refrigerant. A 25 ft line set is included. Longer runs than the included set allows require a different line set, so measure the planned routing before ordering.
What warranty does the MRCOOL DIY Hyper Heat 5th Gen 18,000 BTU (230V) carry?
The manufacturer publishes these warranty tiers: Base: 5 yr parts / 7 yr compressor (standard coverage). Score uses Base.. Registration requirements and proof of qualified installation commonly affect coverage, so read the warranty terms before install day.

Data sources

Show
  1. MRCOOL: MRCOOL DIY Hyper Heat 5th Gen brochure/specificationsSourced - manufacturer technical document

    Covers Frequency, Maximum fuse size, Minimum circuit ampacity, Phase, Voltage range, Manufacturer coverage and more

  2. MRCOOL: MRCOOL DIY Hyper Heat Series Single Zone Installation and Owner's ManualSourced - manufacturer technical document

    Covers Line connection type

  3. MRCOOL-hosted Dasen HVAC storefront: DIY 5th Gen - R454B - 18K Hyper Heat BTU 230V Condenser w/ 25ft Install KitSourced - manufacturer product page

    Covers Maximum line-set length

  4. AHRI certificate #216032551 - search the AHRI DirectorySourced - AHRI directory

    Covers AHRI certification number, Rated cooling capacity, COP at 5F, EER2, Energy Star status, Rated heating capacity and more

  5. MRCOOL: MRCOOL DIY Hyper Heat Series Single Zone Installation and Owner's ManualSourced - manufacturer technical document

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

  6. HVACDirect: HVACDirect product page DIYHH-18-HP-WM-230D25-OSourced - authorized distributor

    Covers Retail price

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

    Covers Legacy compressor warranty value, Legacy warranty value, Warranty notes

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

    Covers Base compressor warranty, Base warranty conditions, Base parts warranty

Last updated

Jul 21, 2026