MRCOOL® DIY® 5th Gen E Star 18,000 BTU Single Zone Mini Split Complete System with 25ft. Line Set 230V — DIY-18-HP-WM-230D25-O

Product Description 

MRCOOL® DIY® 5th Gen 18K BTU Single Zone Mini-Split Air Handler – Powerful, Energy-Efficient Comfort for Your Home

 

Upgrade your home’s heating and cooling systemwith the 5th Gen MRCOOL® DIY® 18K BTU Single Zone Mini-Split Air Handler, designed for effortless DIY installation and year-round climate control in spaces ranging from 500 to 750 sq. ft. Engineered for efficiency, this system features advanced inverter technology, eco-friendly R-454B refrigerant, and smart home integration, ensuring superior comfort without the need for professional installation.

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Effortless DIY Installation – No HVAC Technician Needed

MRCOOL’s patented DIY® technology allows you to install your system quickly and easily—no special tools, vacuum pumps, or professional expertise required.

✔ DIY® QuickConnect® Line Set – Pre-charged with R-454B refrigerant, enabling a vacuum-free, tool-free installation.
✔ DIYPRO® Cable – Enhances safety and durability, eliminating the need for electrical conduit while providing superior protection against outdoor elements and wildlife.
✔ Step-by-Step Installation Guide & Video Support – Clear, user-friendly instructions to help you install with confidence.

 Perfect for homeowners and DIY enthusiasts looking for an affordable, professional-grade HVAC solution!

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Eco-Friendly R-454B Refrigerant – Lower GWP, Higher Efficiency

The 5th Gen MRCOOL® DIY® Mini-Split is designed with R-454B refrigerant, an advanced, environmentally friendly alternative to R-410A.

✔ Lower Global Warming Potential (GWP) – Reduces environmental impact while maximizing efficiency.
✔ ENERGY STAR® Certified Performance – Saves energy and lowers utility bills.
✔ Smart Inverter Technology – Adjusts compressor speed for optimal energy savings and quiet operation.

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Smart Home Integration – Climate Control at Your Fingertips

Enjoy the ultimate convenience with multiple ways to control your indoor comfort:

✔ SmartHVAC App – Adjust settings via your smartphone (iOS & Android) from anywhere.
✔ Voice Command Compatible – Works with Amazon Alexa & Google Assistant for hands-free control.
✔ Wireless Remote Control – Easily manage temperature, fan speed, and modes.
✔ Follow Me® Function – The remote acts as a personal thermostat, adjusting airflow based on its location.
✔ Dry Mode (Dehumidification) – Removes excess moisture to improve indoor air quality and reduce humidity.

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Durability & Long-Lasting Performance

Built to withstand harsh weather conditions, the MRCOOL DIY® Mini-Split is designed for years of reliable performance.

✔ Gold Fin® Condenser – Corrosion-resistant coating protects against salt air, rust, and extreme weather, making it ideal for coastal homes.
✔ Intertek Certified (5031495) – Rigorously tested to meet industry-leading safety and performance standards.
✔ Ultra-Quiet Operation – Experience whisper-quiet heating and cooling, perfect for bedrooms, offices, and living spaces.

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Industry-Leading Warranty – Confidence in Every Purchase

MRCOOL backs the 5th Gen DIY® Mini-Split with an unmatched industry warranty, giving you total peace of mind:

✔ 7-Year Compressor Warranty
✔ 5-Year Parts Warranty

 WHAT'S INCLUDED

• Condenser  DIY-18-HP-C-230D25-O

• 25ft Pre-Charged Line Set  DIY25-1438-O

• Air Handler. DIY-18-HP-WMAH-230D25-O

• Remote Control
  •Communication Wire
  •Wall Sleeve

• DIY Installation

• Smart Phone NOT included. 

SPECIFICATIONS & DIMENSIONS

Dimensions & Weight
Condenser Dimensions	35.04 W" x 13.46 D" x 26.50 H"
Air Handler Dimensions	42.52 W" x 8.90 D" x 13.19 H"
Condenser Weight	93.48 lbs / 42.4 kg
Air Handler Weight	35.49 lbs / 16.1 kg
Capacity & Performance
Zone Capacity	1
Cooling Capacity	18,000 BTU
Outdoor Operating Temperature (Cooling)	-13°F - 122°F
EER2	13.7
SEER2	22.5
Heating Capacity	18,000 BTU
Outdoor Operating Temperature (Heating)	-13°F - 75°F
HSPF2-4	11.5
HSPF2-5	8.5
Coverage Area	500 to 750 sq ft.
Outdoor Noise Level	58.5 dB(A)
Indoor Noise Level (Hi/Mi/Lo)	54.5/44.5/40.5/30.5/19.0 dB(A)
Electrical Requirements
Voltage	208-230V
Phase	1
Cycle	60 Hz
Max Fuse Breaker	20A
Min Circuit Ampacity	18A
Refrigerant & Piping
Refrigerant Type	R-454B
Refrigerant Volume	44.80 oz
Liquid Line Size	1/4"
Suction Line Size	1/2"
Max Line Set Length	98.4 ft.

 

Features
Inverter	DC
Compressor Type	Rotary
Fan Only Option	Yes
Quiet Mode	Yes
Auto Cool	Yes
Wifi Compatibility	Yes
App Compatibility	Yes
Works with IOS	Yes
Works with Android	Yes
Remote Control Included	Yes
Certifications & Warranty
Certifications	UL Listed, ETL Listed, Energy Star Certified, AHRI Certified
Warranty	7 Years Compressor 5 Years Parts

Frequently Asked Questions

What's the difference between the 5th Gen and 4th Gen?

The 5th Gen MRCOOL DIY® Mini Split offers several key upgrades over the 4th Gen, focusing on efficiency, advanced technology, and eco-friendliness.

Here’s what’s new with the 5th Gen:

• Next-Gen R-454B Refrigerant: A more environmentally friendly refrigerant with lower global warming potential (GWP), compliant with the latest HVAC regulations.
• Higher Energy Efficiency: Improved SEER2 ratings for greater energy savings and optimized performance.
• Enhanced System Reliability: Upgraded components for better heating and cooling performance.
  
  

Can I install it myself, or do I need a professional?

The MRCOOL DIY system is designed for homeowners and doesn’t require HVAC tools. You can install the indoor and outdoor units yourself using the pre-charged Quick Connect® lines. However, a licensed electrician is required for the electrical hookup to ensure safety and code compliance.

Does it work in cold weather?
Yes. MRCOOL 5th Gen systems feature low-ambient heating and can provide reliable heat even when outdoor temperatures drop to around 5°F.

How do I know what BTU size I need for my rooms?

A general rule of thumb is 20 BTU per square foot of space. Here's a rough guide:

• 6,000 BTU = 100 - 150 sq ft
• 9,000 BTU = 150 - 350 sq ft
• 12,000 BTU = 351- 500 sq ft
• 18,000 BTU = 501 – 750 sq ft
• 24,000 BTU = 751 – 1,000 sq ft
• 36,000 BTU = 1,001 - 1,500 sq ft

Some additional factors may impact performance such as insulation, ceiling height, sun exposure and the number of appliances in the room. For assistance, contact our Product Experts

Does it heat as well as cool?

Yes. All 5th Gen models are heat pumps, providing both heating and cooling for year-round comfort.

Is it Wi-Fi compatible?

Yes. The MRCOOL SmartHVAC app allows smartphone control and works with Amazon Alexa and Google Assistant.

What is the warranty?

The MRCOOL 5th Generation DIY Mini-Split systems offer the following warranty coverage:

• 7-Year Compressor Replacement Warranty: This warranty ensures that if the compressor fails within the first seven years, MRCOOL will provide a replacement.
• 5-Year Parts Warranty: This warranty covers all parts of the system for five years from the date of purchase.

Recommended Room Types

Perfect for:

• Bedrooms
• Home offices
• Small living rooms
• Tiny homes
• Garages
• Bonus rooms
• Apartments
• Sunrooms

Why Shoppers Trust MRCOOL Direct:

Unlike big-box retailers that sell you a one-size-fits-all kit (and leave you hunting for missing parts), we custom-configure your system so you have everything you need from the start.

• No extra trips to the hardware store.

• No guessing which coupler or cable you need.

• No surprises during installation.

With years of experience specializing in DIY HVAC systems, MRCOOL Direct has earned a reputation as the USA's most trusted independent HVAC dealer.
We are committed to making DIY HVAC installation simple, affordable, and frustration-free — and our custom line set bundling is just one more way we deliver on that promise.

 Need help choosing the right line set length for your project?
Contact our expert team today — we’re here to help you get it done right the first time!

Why Buy from MRCOOL Direct?

As the USA’s #1 most trusted independent MRCOOL Authorized dealer, we provide:

✅ Factory-Direct Pricing – Get the best deals on genuine MRCOOL systems.
✅ Fast & Reliable Shipping – Quick delivery across the lower 48 states.
✅ Expert DIY Support – Need help? Our team is here to assist with installation and troubleshooting.

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Upgrade to the MRCOOL® DIY® 5th Gen 18K BTU Mini-Split Today!

Enjoy powerful, energy-efficient climate control year-round—all with a true DIY-friendly installation. Order now and experience the easiest way to heat and cool your space! 

MRCOOL® 5th Gen DIY vs Easy Pro™ 5th Gen — Which Mini-Split Is the Better Choice?

When you’re investing in a ductless mini-split system, you’re not just buying equipment—you’re buying comfort, reliability, energy savings, and warranty protection for the next decade or more.

MRCOOL® gives homeowners two powerful options: the 5th Generation DIY Series and the Easy Pro™ 5th Gen Series.

Both are designed to simplify installation and deliver efficient year-round comfort, but they are built for different types of customers and use cases.

Below is a straight-forward, expert breakdown so you can choose the system that fits your home, budget, and expectations.

 

 

1. Installation: DIY Game-Changer vs Semi-DIY Convenience 

MRCOOL® 5th Gen DIY — The Only True DIY Mini-Split

The 5th Gen DIY is the industry-leading* self-installation mini-split system.

It uses MRCOOL’s pre-charged QuickConnect® line sets, filled at the factory with R-454B refrigerant.

• No vacuum pumps
• No gauges
• No refrigerant handling
• No HVAC license

Simply connect, tighten, and you’re done.

This technology is why the DIY Series is unmatched in the entire HVAC market.

Comes standard with:

• 25 ft QuickConnect® line set (extendable)
• R-454B refrigerant pre-charged
• Tools-free refrigerant system

This system can be installed in about 3–5 hours with common household tools.

MRCOOL® Easy Pro™ 5th Gen — Easier Than Traditional Systems

The Easy Pro™ uses a 16 ft Fast Connection pre-charged line set, also using R-454B.

This makes Easy Pro ideal for:

• Apartments
• Rental properties
• Light commercial installs
• Homeowners who want professional sign-off

Bottom line:

• DIY 5th Gen = No HVAC professional required
• Easy Pro 5th Gen = Very simplified install, but requires a technician

  

2. Energy Efficiency: The 5th Gen DIY Wins

Both systems are efficient, but the 5th Gen DIY is the performance champion.

5th Gen DIY 9K BTU

• 23.6 SEER2
• One of the most efficient ductless DIY systems available today
• Lower monthly energy use = lower operating cost for life of the unit

 

This matters in real dollars:

• More comfort for less energy
• Better humidity control
• Faster heating and cooling
• Higher performance in extreme climates

Easy Pro 9K BTU

• 20.2 SEER2
• Still excellent vs traditional mini-splits
• Ideal for moderate climates and budget installations

 

Efficiency takeaway:

If you want the lowest energy bills, the 5th Gen DIY is the clear winner.

 

3. Warranty Protection: The Biggest Difference

Here’s where MRCOOL separates casual systems from premium investment-grade HVAC.

MRCOOL® 5th Gen DIY Warranty

• 7-Year Compressor
• 5-Year Parts

 

This is industry-defining coverage—unmatched by any competitor in the DIY space.

It shows MRCOOL’s confidence in the engineering of their flagship product.

MRCOOL® Easy Pro Warranty

• 2-Year Compressor
• 1-Year Parts
• Registration required

It offers solid protection, but nowhere near the level of the DIY Series.

If long-term reliability matters to you — choose 5th Gen DIY.

4. Smart Features & App Control

Both systems deliver advanced comfort, but the 5th Gen DIY includes more premium features.

5th Gen DIY:

• Voice control (Alexa / Google Assistant)
• Follow Me comfort sensor
• Advanced inverter technology
• Higher cold climate performance
• Better humidity and noise reduction

Easy Pro:

• Quiet operation
• Basic app and smart features
• Excellent temperature stability

If you want technology that feels luxury, the DIY Series is a step above. 

5. Line Set Length: Flexibility Matters

Space planning is a real-world problem.

DIY 5th Gen

• Standard 25 ft
• Expandable with extensions
• Perfect for multi-room or attic/basement runs
• Great for coastal or large properties

Easy Pro

• Standard 16 ft
• Fits small rooms, garages, and simple layouts

Longer lines = more flexibility and fewer compromises. 

Which One Should You Choose?

 Choose MRCOOL® 5th Gen DIY if you want:

• True homeowner installation — no HVAC tech required
• 23.6 SEER2 efficiency or higher
• Lower monthly energy bills
• Stronger long-term reliability
• 25 ft line set flexibility
• Premium smart features
• Coastal-grade durability

This is the flagship MRCOOL system.

If you want the best performance and future-proof value, choose DIY 5th Gen.

 

Choose MRCOOL® Easy Pro if you want:

• MRCOOL quality at a lower entry price
• If you want shorter line lengths (16 ft)
• A simpler installation than traditional systems
• Quiet comfort without high-end features
• Solid performance for smaller rooms or secondary spaces
• You plan to use a professional installer

 

This is the budget-friendly way to get MRCOOL performance.

The Bottom Line

Both the MRCOOL® Easy Pro™ and 5th Gen DIY mini-splits deliver real comfort, inverter technology, and simple installation.

But they are not the same class of product:

• MRCOOL® 5th Gen DIY = Premium performance, best-in-class efficiency, and industry-leading warranties.
• MRCOOL® Easy Pro™ = A more affordable way to upgrade comfort with simplified installation.

 

If you want maximum efficiency, reliability, smart features, and the strongest warranty in HVAC, the 5th Gen DIY stands alone.

If you need solid performance at a lower cost, and you don’t mind a less warranty protection, the Easy Pro is the perfect fit.

Need help sizing the right capacity (9K, 12K, 18K, 24K+)?

Call us MRCOOL DIRECT we’ll get you matched correctly—fast, accurate, and homeowner-friendly.