What's in the box
- 1 × MRCOOL® DIY® 18K 5th Gen Condenser — DIY-18-HP-C-230D25-O
- 1 × MRCOOL® DIY® 18K 5th Gen Air Handler — DIY-18-HP-WMAH-230D25-O
- 1 × 25 ft Quick Connect® Line Set, 1/4" × 1/2"
- 1 × MRCOOL® Remote Control
- 1 × DIYPRO® Cable
- Installation documentation
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-WM-230D25-O
More Power. Bigger Spaces. DIY Simple.
The MRCOOL® DIY® 5th Gen 18K BTU Single-Zone Mini-Split System (208/230V) delivers quiet, energy-efficient heating and cooling for spaces up to approximately 800 sq ft — all in one complete system designed for reliable year-round comfort.
Ideal for living rooms, larger bedrooms, garages, basements, open-plan spaces, home offices, and medium-to-large living areas, this system combines dependable performance, smart control, and simplified installation in one streamlined solution built for everyday use.
The system includes a wall-mounted indoor air handler, outdoor condenser, 25 ft Quick Connect® pre-charged line set with R-454B refrigerant, and DIYPRO® cable.
Control your comfort from anywhere using the SmartHVAC app on Apple or Android devices, or enjoy hands-free voice control with Amazon Alexa and Google Assistant.
Why You’ll Love It
✅ Ideal for spaces up to ~ 800 sq ft
✅ Heating & cooling in one complete system
✅ Smart app control with Alexa & Google Assistant
✅ Quiet performance for living spaces and larger rooms
✅ 25 ft Quick Connect® pre-charged line set included
✅ Energy-efficient DC inverter technology
✅ Gold Fin® coating for added durability
Best For
Living Rooms • Large Bedrooms • Garages • Basements • Open-Plan Spaces • Home Offices
What's Included
- 1 × MRCOOL® DIY® 18K 5th Gen Condenser — DIY-18-HP-C-230D25-O
- 1 × MRCOOL® DIY® 18K 5th Gen Air Handler — DIY-18-HP-WMAH-230D25-O
- 1 × 25 ft Quick Connect® Line Set, 1/4" × 1/2"
- 1 × MRCOOL® Remote Control
- 1 × DIYPRO® Cable
- Installation documentation
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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