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
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Designed for simplified installation using MRCOOL® Quick Connect® technology.
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Local electrical requirements and building codes may vary.
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Professional electrical work may still be recommended depending on local regulations and installation requirements.
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Always review the installation manual before purchase and installation.
- 7-Year Compressor Warranty
- 5-Year Parts Warranty
Please refer to the Warranty Document above for full coverage details, terms, and registration requirements.
- Free U.S. curbside delivery within the Lower 48 States on qualifying orders
- Orders ship from U.S. warehouses
- Delivery times may vary by location and carrier availability
- Returns accepted within 30 days for unused and uninstalled products
- Approved returns may be subject to a restocking fee
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
Need More Heating & Cooling Power?
Explore larger systems for bigger spaces or higher heating and cooling demands:
- 24K BTU Systems
- 36K BTU Systems
- Multi-Zone Systems
| Specification | Details |
|---|---|
| Coverage Area | Up to 800 sq ft |
| Cooling Capacity | 18,000 BTU |
| Heating Capacity | 18,000 BTU |
| Voltage | 208/230V |
| Zone Type | Single Zone |
| SEER2 | 22.5 |
| EER2 | 13.7 |
| HSPF2-4 | 11.5 |
| HSPF2-5 | 8.5 |
| Indoor Sound Level | 19–54.5 dB(A) |
| Outdoor Sound Level | 58.5 dB(A) |
| WiFi Compatible | Yes |
| Voice Assistant | Alexa & Google Assistant |
| Inverter Technology | DC Inverter |
| Refrigerant | R-454B |
| Refrigerant Volume | 44.8 oz |
| Line Set Length | 25 ft |
| Max Line Set Length | 98.4 ft |
| Line Sizes | 1/4" Liquid / 1/2" Suction |
| Compressor Type | Rotary |
| Certifications | AHRI, UL, ETL, Energy Star® |
| Warranty | 7-Year Compressor / 5-Year Parts |
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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