What's in the box
- MRCOOL® 12K 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-12-HP-WMAH-115D25-O
Powerful, Ultra-Quiet Comfort for Spaces up to 550 sq. ft.
The MRCOOL® 12k BTU DIY® 5th Generation Mini-Split Air Handler offers efficient, whisper-quiet heating and cooling designed for easy, do-it-yourself installation. Perfect for bedrooms, offices, and medium-sized living spaces up to 550 sq. ft., this unit pairs seamlessly with your MRCOOL® DIY® 5th Gen Single-Zone or Multi-Zone Condenser.
Featuring a pre-charged 25-foot Quick Connect® line set filled with eco-friendly R-454B refrigerant, this system eliminates the need for vacuum pumps or professional HVAC installation. The included DIYPro™ Communication Cable replaces traditional electrical conduit, offering durability against outdoor elements.
Control your climate effortlessly with the SmartHVAC® app, Amazon Alexa, or Google Assistant voice commands. The built-in Follow Me® function senses the temperature at the wireless remote’s location, maintaining your ideal comfort level.
Built for long-lasting performance, the Gold Fin® corrosion-resistant coating makes this air handler ideal for coastal or humid environments. Enjoy dependable, efficient, year-round comfort backed by one of the industry’s leading warranties.
Why You’ll Love It
✅ Perfect for Medium Spaces — Ideal for bedrooms, home offices, and dens up to 550 sq. ft.
✅ True DIY Installation — Quick Connect® line sets and DIYPro™ cable make setup simple — no HVAC pro required
✅ Smart-Home Ready — Wi-Fi enabled, compatible with SmartHVAC® app, Alexa, and Google Assistant
✅ Follow Me® Personal Comfort — Wireless remote tracks your location to deliver customized comfort
✅ Ultra-Quiet Operation — Peaceful performance as low as 18 dBA
✅ Gold Fin® Protection — Anti-corrosion coating ensures durability in tough climates
✅ All-Season Heating & Cooling — Operates from 5°F to 86°F, delivering comfort year-round
✅ Industry-Leading Warranty — Limited Lifetime Compressor Warranty (with registration), 7-Year Compressor, 5-Year Parts
What’s Included:
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MRCOOL® 12K 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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