What's in the box
- MRCOOL® 18K DIY® 5th Gen Mini-Split Air Handler
- 25ft DIYPro™ Communication Cable
- Wireless Remote Control
- Installation Accessories
- MRCOOL® Warranty
Free curbside shipping on eligible MRCOOL® systems across the continental U.S. Most products ship in 3–5 business days and arrive in 4–10 days, depending on your location. Freight carriers will call to schedule delivery.
Returns accepted within 30 days on new, unopened items in original packaging. A restocking fee of up to 35% may apply for HVAC equipment — we’ll always confirm before issuing a return authorization.
Each MRCOOL® system is backed by manufacturer warranty coverage as defined by product and model — typically 5–10 years on major components. Register your system after installation to activate full coverage.
Need help with sizing, voltage or compatibility? Email support@coolheatdirect.com — our U.S. team replies within one business day.
Manuals & documents
MODEL: DIY-18-HP-WMAH-115D25-O
Powerful, Ultra-Quiet Comfort for Spaces up to 1,000 sq. ft.
The MRCOOL® 18k BTU DIY® 5th Generation Mini-Split Air Handler delivers high-capacity, whisper-quiet heating and cooling designed for hassle-free, do-it-yourself installation. Perfect for large bedrooms, open-concept living rooms, basements, and studios up to 1,000 sq. ft., this air handler pairs seamlessly with your MRCOOL® DIY® 5th Gen Single-Zone or Multi-Zone Condenser.
The pre-charged 25-foot Quick Connect® line set comes filled with eco-friendly R-454B refrigerant, eliminating the need for vacuum pumps or professional HVAC installation. Included DIYPro™ Communication Cable replaces bulky electrical conduit while standing up to the elements.
Effortlessly control your home’s climate through the SmartHVAC® app, Amazon Alexa, or Google Assistant voice commands. The built-in Follow Me® function ensures your room stays at your ideal temperature by sensing the remote’s location.
Protected with Gold Fin® anti-corrosion coating, this unit is made for long-lasting performance, even in coastal and humid climates. Enjoy year-round heating and cooling backed by one of the best warranties in the HVAC industry.
Why You’ll Love It
✅ Ideal for Mid-to-Large Spaces — Perfect for open-plan areas, large bedrooms, and living rooms up to 1,000 sq. ft.
✅ True DIY Installation — No HVAC license or vacuum pump needed with Quick Connect® line sets and DIYPro™ cable.
✅ Smart Home Compatible — Wi-Fi enabled, works with SmartHVAC® app, Alexa, and Google Assistant.
✅ Follow Me® Technology — Maintains precise comfort based on your remote’s location.
✅ Ultra-Quiet Operation — As low as 24 dBA for a peaceful, uninterrupted environment.
✅ Gold Fin® Condenser Protection — Rust-resistant coating built for coastal conditions.
✅ All-Season Heating & Cooling — Effective operation from 5°F to 86°F, for true year-round comfort.
✅ Industry-Leading Warranty — Lifetime Limited Compressor Warranty (with registration), 7-Year Compressor Warranty, and 5-Year Parts Warranty.
What’s Included:
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MRCOOL® 18K DIY® 5th Gen Mini-Split Air Handler
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25ft DIYPro™ Communication Cable
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Wireless Remote Control
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Installation Accessories
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MRCOOL® Warranty
Questions, answered
Everything homeowners ask before buying a MRCOOL® system.
Installation
Do I need an HVAC technician to install this?
No. MRCOOL® DIY systems are designed for homeowner installation. The pre-charged Quick Connect® line set means there's no refrigerant handling, no vacuum pump, and no special tools or license required.
How long does installation take?
Most single-zone systems go in within a few hours: mount the indoor air handler, set the outdoor condenser, connect the pre-charged line set, and power it on.
Do I need an electrician?
The system needs a dedicated circuit. Most homeowners have a licensed electrician add the breaker and disconnect — everything else you can do yourself.
Sizing & compatibility
What BTU size do I need?
As a rule of thumb: up to 400 sq ft → 9–12K BTU, 400–600 sq ft → 12–18K, 600–1,000 sq ft → 18–24K. Use the room-size guide above and factor in insulation, ceiling height and sun exposure.
Will it heat in winter?
Yes — these are heat pumps, so they heat and cool. Many MRCOOL® systems keep heating in sub-freezing temperatures; check each model's spec sheet for its low-temperature heating range.
115V or 230V — which do I need?
9K–12K units are usually 115V (standard outlet circuit); 18K and larger are typically 230V. The voltage is shown in the product options and specifications.
Warranty & support
What warranty is included?
MRCOOL® systems carry manufacturer warranty coverage — typically 5–10 years on major components when you register your system after installation.
How do I get help choosing or installing?
Email support@coolheatdirect.com — our U.S. team replies within one business day with sizing, voltage and compatibility help.
Shipping & returns
How fast does it ship?
Most products ship in 3–5 business days with free curbside delivery in the continental U.S. The freight carrier calls to schedule your delivery.
Can I return it?
Returns are accepted within 30 days on new, unopened items in original packaging. A restocking fee may apply to HVAC equipment — we always confirm before issuing a return authorization.
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