What's in the box
- 1 × MRCOOL® DIY® Hyper Heat 18K BTU Condenser
- 1 × MRCOOL® DIY® 18K BTU 5th Gen Wall-Mounted Air Handler
- 1 × 25 ft QuickConnect® Line Set (1/4" × 1/2")
- 1 × MRCOOL® Remote Control
- 1 × DIYPRO® Cable
- Designed for simplified installation using MRCOOL® QuickConnect® technology
- No vacuum pump or specialized HVAC equipment required
- Local electrical requirements and building codes may vary
- Professional electrical work may still be recommended depending on local regulations
- 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: DIYHH-18-HP-WM-230D25-O
Built for Winter.
Extreme Cold Heating. Powerful Cooling. DIY Simple.
Still worried your home won't stay warm when temperatures plunge?
The MRCOOL® DIY® Hyper Heat 18K BTU Mini Split System was built for homeowners who refuse to let winter dictate their comfort. While many heating systems struggle in extreme cold, Hyper Heat technology continues delivering reliable heating in temperatures as low as -22°F, helping keep your space warm, comfortable, and energy efficient when you need it most.
Perfect for living rooms, large bedrooms, home offices, cabins, basements, workshops, and other spaces up to 800 sq ft, this complete system combines a MRCOOL® DIY® Hyper Heat Condenser and a MRCOOL® DIY® 18K 5th Generation Wall-Mounted Air Handler to provide dependable heating, cooling, and year-round comfort. The included 25 ft QuickConnect® line set comes pre-charged with environmentally friendly R-454B refrigerant, helping simplify installation without specialized HVAC tools.
Advanced DC inverter technology, impressive 21.2 SEER2 efficiency, SmartHVAC® app control, Amazon Alexa®, Google Assistant®, and the included DIYPRO® cable give you complete control, outstanding efficiency, and dependable comfort in every season.
Whether it's a freezing winter morning or the hottest day of summer, Hyper Heat delivers the confidence of knowing your comfort system is ready.
Warm when others struggle. Cool when others quit. Built for extreme climates.
Why You'll Love It
✅ Reliable heating in temperatures as low as -22°F
✅ Ideal for spaces between 550–800 sq ft
✅ High-efficiency 21.2 SEER2 performance
✅ Simplified DIY installation with QuickConnect® technology
✅ SmartHVAC® app control from anywhere
✅ Compatible with Amazon Alexa® & Google Assistant®
✅ Gold Fin® corrosion-resistant condenser protection
✅ Includes 25 ft pre-charged QuickConnect® line set
✅ Energy-saving DC inverter technology
Best For
Living Rooms • Large Bedrooms • Home Offices • Cabins • Basements • Workshops • Studios • Cold Climate Homes
Need More Heating & Cooling Power?
Explore larger systems for bigger spaces or higher heating and cooling demands:
| Coverage Area | 550–800 sq ft |
| Cooling Capacity | 18,000 BTU |
| Heating Capacity | 18,000 BTU |
| Voltage | 208/230V |
| Zone Type | Single Zone |
| SEER2 | 21.2 |
| EER2 | 12.5 |
| HSPF2-4 | 11.0 |
| HSPF2-5 | 8.5 |
| Refrigerant | R-454B |
| Inverter Technology | DC Inverter |
| Compressor Type | Rotary |
| Sound Level (Outdoor) | 58 dB(A) |
| Minimum Cooling Temperature | -22°F |
| Minimum Heating Temperature | -22°F |
| WiFi Compatible | Yes |
| Voice Control | Alexa® & Google Assistant® |
| Line Set Length | 25 ft |
| Maximum Line Set Length | 75 ft |
| Line Sizes | 1/4" Liquid / 1/2" Suction |
| Certifications | ENERGY STAR®, AHRI, ETL, UL, CSA |
| 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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