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 What's Included 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 Control1 × DIYPRO® Cable Specifications 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 Room Size & BTU Guide BTU Rating Recommended Space 12K BTU 350–550 sq ft 18K BTU (This System) 550–800 sq ft Room size recommendations may vary depending on insulation quality, ceiling height, climate zone, window exposure, and room layout. Need More Heating & Cooling Power? Explore larger systems for bigger spaces or higher heating and cooling demands: DIY® Multi-Zone Systems Universal® Central Systems Central Ducted Systems Installation Installation Notes 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 Installation & Manuals Product Brochure Installation Manual Warranty Document Warranty Information 7-Year Compressor Warranty 5-Year Parts Warranty Please refer to the Warranty Document above for full coverage details, terms, and registration requirements. Shipping & Returns Free standard shipping is available on eligible orders to the Lower 48 states and Washington, D.C. Orders are generally processed within 3–5 business days, followed by approximately 5–12 business days in transit. Smaller items may ship by parcel carrier. Larger equipment may be delivered curbside by freight carrier, and the carrier may contact you to coordinate delivery. Return requests may be submitted within 30 calendar days of delivery. Products must be new, unused, uninstalled, complete and in their original manufacturer packaging. Powered products must not have been energized. For approved change-of-mind, incorrect-sizing or customer-ordering-error returns, the customer is responsible for return freight and a 15% restocking fee. Verified damaged, defective, incorrect or incomplete orders are handled separately. View our Shipping Policy and Returns & Warranty Policy.