• MRCOOL DIY Hyper Heat 18,000 BTU OuttaSight® ceiling cassette air handler for single zone mini split, recessed low-profile design ideal for larger rooms needing powerful heating and cooling.
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MRCOOL® HyperHeat®

MRCOOL DIYHH-18 Hyper Heat 18K Mini Split Complete DIY Bundle – 5th Gen (230V)

MRCOOL DIYHH-18 Hyper Heat 18K Mini Split Complete DIY Bundle – 5th Gen (230V)

SKUMC-DIY-HH18-CASS18-25

TypeSingle Zone Mini Split System

$3,719.00
$3,719.00 $4,648.75
You Save: $929.75
SALE Sold out
Shipping calculated at checkout.

Refrigerant Type: R-454B

Line Set Length
In stock
Ready to ship
Free delivery*
Ships in 1–2 business days
Estimated arrival: Jul 10 – Jul 12
Based on order date & typical delivery times
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PRODUCT DESCRIPTION

MRCOOL DIYHH-18 Hyper Heat 18K Complete DIY Mini Split Bundle

Model Bundle: MRD-DIYHH18-WM18-25

The MRCOOL DIYHH-18 Hyper Heat 18K Mini Split Bundle is a true cold-climate DIY ductless heat pump system designed for powerful heating and cooling performance in garages, bonus rooms, basements, shops, offices, cabins, apartments, and other hard-to-condition spaces.

This 5th Gen MRCOOL Hyper Heat system delivers reliable comfort in extreme winter conditions, with heating operation down to -22°F. Unlike standard mini splits that begin losing heating capacity as temperatures drop, the DIYHH-18 uses advanced inverter technology, optimized refrigerant control, and cold-climate system design to maintain strong performance when you need it most.

The included No-Vac® QuickConnect® pre-charged line set allows for a true DIY installation without vacuum pumps, refrigerant charging, gauges, nitrogen, or EPA certification. The system uses R-454B refrigerant, built-in Wi-Fi, SmartHVAC® App control, and compatibility with Amazon Alexa® and Google Assistant®.

What’s Included in This Complete DIY Bundle?

  • DIYHH-18-HP-C-230D25-O – MRCOOL Hyper Heat 18K Outdoor Condenser, 230V, R-454B
  • DIYCASSETTE18HP-230D25-O – MRCOOL DIY 5th Gen OuttaSight® 18K One-Way Ceiling Cassette
  • DIY25-1412 – 25 ft Pre-Charged QuickConnect® No-Vac Line Set
  • DIYPRO® Communication Cable

Why Choose the MRCOOL DIYHH-18 Hyper Heat System?

  • True cold-climate Hyper Heat performance down to -22°F
  • DIY-friendly QuickConnect® installation with no vacuuming required
  • Efficient 18,000 BTU heating and cooling performance
  • Ideal for garages, shops, basements, bonus rooms, cabins, and additions
  • R-454B refrigerant for newer-generation system design
  • Inverter compressor technology for steady comfort and lower energy use
  • Quiet operation compared to window units, portable ACs, and space heaters
  • Built-in Wi-Fi with SmartHVAC® App control
  • Works with Amazon Alexa® and Google Assistant®
  • Gold Fin® condenser protection for improved durability

Hyper Heat vs Standard Mini Splits

Standard DIY mini splits are excellent for mild and moderate climates, but many begin losing heating output as outdoor temperatures fall below freezing. The MRCOOL DIYHH-18 Hyper Heat system is designed for colder regions where winter performance matters.

If your winter temperatures regularly dip below 20°F, Hyper Heat is the better choice. It is built to keep producing usable heat down to -22°F instead of simply surviving cold weather like some allegedly “heating capable” systems do while quietly giving up in the corner.

Ideal Applications

  • Garages and workshops
  • Bonus rooms and room additions
  • Basements and attics
  • Master bedrooms
  • Home gyms and studios
  • Offices and retail suites
  • Cabins and mountain homes
  • Barndominiums and pole barns
  • Detached buildings and outbuildings
  • Airbnb and rental properties

Condenser Specifications

Specification Details
Outdoor Model DIYHH-18-HP-C-230D25-O
System Type Single-Zone Hyper Heat Mini Split
Cooling Capacity 18,000 BTU
Heating Capacity 18,000 BTU
Voltage 208/230V
Phase 1 Phase
Frequency 60 Hz
SEER2 21.2
HSPF2 11
Recommended Coverage Up to 800 sq ft
Refrigerant R-454B
Compressor Type Rotary Inverter
Metering Device Electronic Expansion Valve, EEV
Minimum Heating Ambient Temperature -22°F
Minimum Cooling Ambient Temperature -22°F
Outdoor Noise Level Up to 58 dBA
Energy Star Certified Yes
AHRI Certified Yes

Electrical Specifications

Electrical Requirement Details
Voltage 208/230V
Max Fuse / Breaker 25A
Minimum Circuit Ampacity 19A
Dedicated Circuit Required Yes

Line Set Specifications

Line Set Detail Specification
Included Line Set 25 ft QuickConnect® No-Vac Pre-Charged Line Set
Liquid Line Size 1/4 in.
Suction Line Size 1/2 in.
Maximum Line Set Length 75 ft
Vacuum Pump Required No
Refrigerant Charging Required No

Ceiling Cassette Specifications

Specification Details
Indoor Model DIYCASSETTE18HP-230D25-O
Indoor Unit Type OuttaSight® One-Way Ceiling Cassette
Capacity 18,000 BTU
Mounting Type Flush Ceiling Mount
Joist Compatibility Designed for 16 in. on-center joists
Air Direction One-Way Low Profile Airflow
Operating Modes Auto, Cool, Heat, Dry, Fan Only, Sleep
Filter Reusable/Washable Filter
Smart Control Wi-Fi App, Amazon Alexa®, Google Assistant®
Indoor Noise Level 24–41 dBA
Breaker Size 15A Dedicated Circuit
Minimum Circuit Ampacity 3A

Line Set Length Information

This bundle includes a standard 25 ft pre-charged QuickConnect® line set. Extended line set options may include an additional line set, couplers, and a longer communication cable for installations that require extra distance between the indoor and outdoor units.

Important Electrical Note

Each outdoor unit requires its own dedicated electrical circuit. Proper electrical installation helps prevent system issues, nuisance trips, warranty problems, and the kind of avoidable chaos that keeps HVAC techs muttering under their breath.

Frequently Asked Questions

Can I install this MRCOOL Hyper Heat mini split myself?

Yes. This system uses MRCOOL No-Vac® QuickConnect® pre-charged line sets, which means no vacuum pump, no gauges, no nitrogen purge, and no field refrigerant charging are required.

Do I need to buy refrigerant?

No. The system is factory pre-charged and designed for use with the included QuickConnect® line set.

Will this heat in extreme cold?

Yes. The MRCOOL DIYHH-18 Hyper Heat system is designed to provide heating operation down to -22°F.

Is this better than a window AC or portable air conditioner?

Yes. A ductless mini split is quieter, more efficient, more permanent, and better suited for year-round heating and cooling than most window units or portable AC systems.

Can this be used in a garage, shop, or detached building?

Yes. This system is a strong choice for garages, workshops, outbuildings, cabins, and other spaces where cold-climate heating and efficient cooling are both needed.

Can this system be used in a rental or Airbnb?

Yes. A Hyper Heat mini split can improve guest comfort, reduce heating complaints, and add long-term value to rental properties.

Why Buy From MRCOOL DIY Direct?

MRCOOL DIY Direct specializes in MRCOOL systems, parts, bundles, and support. You are not buying from a random dropshipper guessing their way through HVAC equipment. Our team can help verify sizing, electrical requirements, line set selection, and system compatibility before you order.

If you want the right MRCOOL DIY Hyper Heat system for your space, we can help make sure you get the correct equipment the first time.

Rated 4.7 / 5 Stars
4700+ Verified Reviews

Comfort That Speaks for Itself

See why homeowners and pros alike trust MRCOOL DIY systems to deliver comfort, savings, and easy installation.

I never thought I’d install my own HVAC system, but MRCOOL made it possible. The instructions were easy, and the pre-charged lines saved me from hiring a tech. Cools my garage workshop perfectly!

Jason R., North Carolina

Our MRCOOL mini-split runs really quiet — you can barely tell it’s on. Our electric bill dropped about 35% this summer. Very impressed with the efficiency

Megan L., Arizona

Installed this in my detached office. Took me a Saturday morning and a friend to lift the outdoor unit. Works flawlessly — heats in winter and cools in summer.

Daniel P., Texas

I swapped my old central unit for two MRCOOL DIY mini-splits. Same comfort, way lower bills. The inverter technology really makes a difference.

Jennifer C., Florida

Had a small question during installation and Vanessa picked up right away. They walked me through it step by step — best customer service I’ve had in years.

Chris B., Ohio

Keeps our sunroom comfortable in 100°F summers and comfy in the winter. The heat pump feature is amazing — one system for both heating and cooling!

Angela K., Kentucky

I’ve remodeled a few homes, and MRCOOL DIY systems are a game-changer. No need for HVAC pros or special tools — everything is plug-and-play.

Brandon S., Tennessee

I never thought I’d install my own HVAC system, but MRCOOL made it possible. The instructions were easy, and the pre-charged lines saved me from hiring a tech. Cools my garage workshop perfectly!

Jason R., North Carolina

Our MRCOOL mini-split runs really quiet — you can barely tell it’s on. Our electric bill dropped about 35% this summer. Very impressed with the efficiency

Megan L., Arizona

Installed this in my detached office. Took me a Saturday morning and a friend to lift the outdoor unit. Works flawlessly — heats in winter and cools in summer.

Daniel P., Texas

I swapped my old central unit for two MRCOOL DIY mini-splits. Same comfort, way lower bills. The inverter technology really makes a difference.

Jennifer C., Florida

Had a small question during installation and Vanessa picked up right away. They walked me through it step by step — best customer service I’ve had in years.

Chris B., Ohio

Keeps our sunroom comfortable in 100°F summers and comfy in the winter. The heat pump feature is amazing — one system for both heating and cooling!

Angela K., Kentucky

I’ve remodeled a few homes, and MRCOOL DIY systems are a game-changer. No need for HVAC pros or special tools — everything is plug-and-play.

Brandon S., Tennessee

I never thought I’d install my own HVAC system, but MRCOOL made it possible. The instructions were easy, and the pre-charged lines saved me from hiring a tech. Cools my garage workshop perfectly!

Jason R., North Carolina

Our MRCOOL mini-split runs really quiet — you can barely tell it’s on. Our electric bill dropped about 35% this summer. Very impressed with the efficiency

Megan L., Arizona

Installed this in my detached office. Took me a Saturday morning and a friend to lift the outdoor unit. Works flawlessly — heats in winter and cools in summer.

Daniel P., Texas

I swapped my old central unit for two MRCOOL DIY mini-splits. Same comfort, way lower bills. The inverter technology really makes a difference.

Jennifer C., Florida

Had a small question during installation and Vanessa picked up right away. They walked me through it step by step — best customer service I’ve had in years.

Chris B., Ohio

Keeps our sunroom comfortable in 100°F summers and comfy in the winter. The heat pump feature is amazing — one system for both heating and cooling!

Angela K., Kentucky

I’ve remodeled a few homes, and MRCOOL DIY systems are a game-changer. No need for HVAC pros or special tools — everything is plug-and-play.

Brandon S., Tennessee

I never thought I’d install my own HVAC system, but MRCOOL made it possible. The instructions were easy, and the pre-charged lines saved me from hiring a tech. Cools my garage workshop perfectly!

Jason R., North Carolina

Our MRCOOL mini-split runs really quiet — you can barely tell it’s on. Our electric bill dropped about 35% this summer. Very impressed with the efficiency

Megan L., Arizona

Installed this in my detached office. Took me a Saturday morning and a friend to lift the outdoor unit. Works flawlessly — heats in winter and cools in summer.

Daniel P., Texas

I swapped my old central unit for two MRCOOL DIY mini-splits. Same comfort, way lower bills. The inverter technology really makes a difference.

Jennifer C., Florida

Had a small question during installation and Vanessa picked up right away. They walked me through it step by step — best customer service I’ve had in years.

Chris B., Ohio

Keeps our sunroom comfortable in 100°F summers and comfy in the winter. The heat pump feature is amazing — one system for both heating and cooling!

Angela K., Kentucky

I’ve remodeled a few homes, and MRCOOL DIY systems are a game-changer. No need for HVAC pros or special tools — everything is plug-and-play.

Brandon S., Tennessee

I never thought I’d install my own HVAC system, but MRCOOL made it possible. The instructions were easy, and the pre-charged lines saved me from hiring a tech. Cools my garage workshop perfectly!

Jason R., North Carolina

Our MRCOOL mini-split runs really quiet — you can barely tell it’s on. Our electric bill dropped about 35% this summer. Very impressed with the efficiency

Megan L., Arizona

Installed this in my detached office. Took me a Saturday morning and a friend to lift the outdoor unit. Works flawlessly — heats in winter and cools in summer.

Daniel P., Texas

I swapped my old central unit for two MRCOOL DIY mini-splits. Same comfort, way lower bills. The inverter technology really makes a difference.

Jennifer C., Florida

Had a small question during installation and Vanessa picked up right away. They walked me through it step by step — best customer service I’ve had in years.

Chris B., Ohio

Keeps our sunroom comfortable in 100°F summers and comfy in the winter. The heat pump feature is amazing — one system for both heating and cooling!

Angela K., Kentucky

I’ve remodeled a few homes, and MRCOOL DIY systems are a game-changer. No need for HVAC pros or special tools — everything is plug-and-play.

Brandon S., Tennessee

I never thought I’d install my own HVAC system, but MRCOOL made it possible. The instructions were easy, and the pre-charged lines saved me from hiring a tech. Cools my garage workshop perfectly!

Jason R., North Carolina

Our MRCOOL mini-split runs really quiet — you can barely tell it’s on. Our electric bill dropped about 35% this summer. Very impressed with the efficiency

Megan L., Arizona

Installed this in my detached office. Took me a Saturday morning and a friend to lift the outdoor unit. Works flawlessly — heats in winter and cools in summer.

Daniel P., Texas

I swapped my old central unit for two MRCOOL DIY mini-splits. Same comfort, way lower bills. The inverter technology really makes a difference.

Jennifer C., Florida

Had a small question during installation and Vanessa picked up right away. They walked me through it step by step — best customer service I’ve had in years.

Chris B., Ohio

Keeps our sunroom comfortable in 100°F summers and comfy in the winter. The heat pump feature is amazing — one system for both heating and cooling!

Angela K., Kentucky

I’ve remodeled a few homes, and MRCOOL DIY systems are a game-changer. No need for HVAC pros or special tools — everything is plug-and-play.

Brandon S., Tennessee

I never thought I’d install my own HVAC system, but MRCOOL made it possible. The instructions were easy, and the pre-charged lines saved me from hiring a tech. Cools my garage workshop perfectly!

Jason R., North Carolina

Our MRCOOL mini-split runs really quiet — you can barely tell it’s on. Our electric bill dropped about 35% this summer. Very impressed with the efficiency

Megan L., Arizona

Installed this in my detached office. Took me a Saturday morning and a friend to lift the outdoor unit. Works flawlessly — heats in winter and cools in summer.

Daniel P., Texas

I swapped my old central unit for two MRCOOL DIY mini-splits. Same comfort, way lower bills. The inverter technology really makes a difference.

Jennifer C., Florida

Had a small question during installation and Vanessa picked up right away. They walked me through it step by step — best customer service I’ve had in years.

Chris B., Ohio

Keeps our sunroom comfortable in 100°F summers and comfy in the winter. The heat pump feature is amazing — one system for both heating and cooling!

Angela K., Kentucky

I’ve remodeled a few homes, and MRCOOL DIY systems are a game-changer. No need for HVAC pros or special tools — everything is plug-and-play.

Brandon S., Tennessee

I never thought I’d install my own HVAC system, but MRCOOL made it possible. The instructions were easy, and the pre-charged lines saved me from hiring a tech. Cools my garage workshop perfectly!

Jason R., North Carolina

Our MRCOOL mini-split runs really quiet — you can barely tell it’s on. Our electric bill dropped about 35% this summer. Very impressed with the efficiency

Megan L., Arizona

Installed this in my detached office. Took me a Saturday morning and a friend to lift the outdoor unit. Works flawlessly — heats in winter and cools in summer.

Daniel P., Texas

I swapped my old central unit for two MRCOOL DIY mini-splits. Same comfort, way lower bills. The inverter technology really makes a difference.

Jennifer C., Florida

Had a small question during installation and Vanessa picked up right away. They walked me through it step by step — best customer service I’ve had in years.

Chris B., Ohio

Keeps our sunroom comfortable in 100°F summers and comfy in the winter. The heat pump feature is amazing — one system for both heating and cooling!

Angela K., Kentucky

I’ve remodeled a few homes, and MRCOOL DIY systems are a game-changer. No need for HVAC pros or special tools — everything is plug-and-play.

Brandon S., Tennessee

I never thought I’d install my own HVAC system, but MRCOOL made it possible. The instructions were easy, and the pre-charged lines saved me from hiring a tech. Cools my garage workshop perfectly!

Jason R., North Carolina

Our MRCOOL mini-split runs really quiet — you can barely tell it’s on. Our electric bill dropped about 35% this summer. Very impressed with the efficiency

Megan L., Arizona

Installed this in my detached office. Took me a Saturday morning and a friend to lift the outdoor unit. Works flawlessly — heats in winter and cools in summer.

Daniel P., Texas

I swapped my old central unit for two MRCOOL DIY mini-splits. Same comfort, way lower bills. The inverter technology really makes a difference.

Jennifer C., Florida

Had a small question during installation and Vanessa picked up right away. They walked me through it step by step — best customer service I’ve had in years.

Chris B., Ohio

Keeps our sunroom comfortable in 100°F summers and comfy in the winter. The heat pump feature is amazing — one system for both heating and cooling!

Angela K., Kentucky

I’ve remodeled a few homes, and MRCOOL DIY systems are a game-changer. No need for HVAC pros or special tools — everything is plug-and-play.

Brandon S., Tennessee

I never thought I’d install my own HVAC system, but MRCOOL made it possible. The instructions were easy, and the pre-charged lines saved me from hiring a tech. Cools my garage workshop perfectly!

Jason R., North Carolina

Our MRCOOL mini-split runs really quiet — you can barely tell it’s on. Our electric bill dropped about 35% this summer. Very impressed with the efficiency

Megan L., Arizona

Installed this in my detached office. Took me a Saturday morning and a friend to lift the outdoor unit. Works flawlessly — heats in winter and cools in summer.

Daniel P., Texas

I swapped my old central unit for two MRCOOL DIY mini-splits. Same comfort, way lower bills. The inverter technology really makes a difference.

Jennifer C., Florida

Had a small question during installation and Vanessa picked up right away. They walked me through it step by step — best customer service I’ve had in years.

Chris B., Ohio

Keeps our sunroom comfortable in 100°F summers and comfy in the winter. The heat pump feature is amazing — one system for both heating and cooling!

Angela K., Kentucky

I’ve remodeled a few homes, and MRCOOL DIY systems are a game-changer. No need for HVAC pros or special tools — everything is plug-and-play.

Brandon S., Tennessee

Why Buy From Us

Why Buy from MRCOOL DIY Direct?

Trusted nationwide for MRCOOL DIY systems, support, and installation guidance.

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Top MRCOOL Dealer

Trusted nationwide for DIY mini split systems.

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DIY System Experts

Specializing in MRCOOL DIY systems and support.

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Fast Shipping

Quick delivery across the lower 48 states.

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Real Support

Help with sizing, compatibility, and installation.

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Family-Owned

Based in Missouri, serving nationwide.

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Complete System Guidance

We help you get everything needed for install.