MRCOOL DIYHH-18 Hyper Heat 18K BTU Condenser – 5th Gen, -22°F Heating, R-454B, 230V DIY QuickConnect

MRCOOL® DIYHH-18 Hyper Heat 18K BTU Condenser – 5th Gen DIY QuickConnect® (230V)

New for 2025 – 18K Hyper Heat DIY Condenser with Pre-Charged 25 ft Line Set

The MRCOOL® DIYHH-18-HP-C-230D25-O is the strongest 18,000 BTU Hyper Heat DIY condenser on the market, engineered for powerful year-round comfort and reliable heating down to –22°F. This 5th Gen outdoor unit ships with a factory-charged R-454B QuickConnect® line set so you can install it without vacuum pumps, gauges, EPA licenses, or refrigerant handling.

This listing is for the condenser and 25 ft pre-charged line set only. Pair it with a compatible MRCOOL DIY wall mount air handler or DIY OuttaSight® ceiling cassette (sold separately).

IMPORTANT: This is a 208/230V condenser. It cannot be used with 115V air handlers.

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The 5th Gen DIY Mini Split Condenser That Leaves Others Behind

If you want the best 18K BTU DIY mini split condenser for cold climates, you are looking at it. The DIYHH-18 Hyper Heat condenser is built on MRCOOL’s 5th Generation platform, delivering:

• Stronger heat output at low temperatures
• Higher efficiency with 21.2 SEER2 and 11 HSPF2
• Next-generation R-454B low-GWP refrigerant
• More durable outdoor performance with Gold Fin® anti-corrosion
• Cleaner, quieter inverter rotary compressor operation

No refrigerant handling. No vacuum pump. No licensed HVAC installer. Just connect, tighten, and turn it on. This condenser is a big part of why MRCOOL dominates the DIY mini split market.

Hyper Heat Performance for Real Winters

Most “DIY mini splits” start losing capacity or shutting down as temperatures approach freezing. The MRCOOL DIYHH-18 Hyper Heat delivers usable heat down to –22°F, making it unstoppable in:

• Midwest and Northeast winters
• Tennessee & Kentucky cold snaps
• Mountain and northern states
• Coastal climates with wind, rain, and salt exposure

You will not find this capability on cheap brands or older 4th Gen units.

Smarter, Quieter, More Efficient

The 5th Gen inverter technology modulates compressor output to maintain steady comfort without harsh on/off cycling or loud startup noise. The result:

• Lower energy bills
• Longer component life
• Faster temperature recovery
• Premium comfort you can feel in every season

This condenser is ideal for master bedrooms, home offices, garages, workshops, barndominiums, tiny homes, ADUs, apartments, bonus rooms, and any space where ductwork is a headache.

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What’s Included

• MRCOOL DIYHH-18-HP-C-230D25-O Hyper Heat 18K Outdoor Condenser
• DIY25-1412 25 ft pre-charged R-454B QuickConnect® line set
• Installation hardware & documentation

No vacuuming or refrigerant tools required.

Compatible Indoor Units (Sold Separately)

• DIY-18-HP-WMAH-230D25-O Wall Mount Air Handler
• DIYCASSETTE18HP-230D25-O OuttaSight® Ceiling Cassette

Both indoor units connect using MRCOOL’s factory-sealed QuickConnect® fittings for fast DIY installation.

NOTE: This 18K Hyper Heat condenser is 208/230V only and will not work with 115V DIY air handlers.

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Key Features

• Hyper Heat performance down to –22°F
• 21.2 SEER2 high-efficiency cooling
• 11 / 8.5 HSPF2 heating efficiency
• R-454B next-generation low-GWP refrigerant
• 25 ft factory-charged QuickConnect® line set included
• Compatible with DIYPRO® cable (included with indoor unit)
• SmartHVAC™ app, Amazon Alexa & Google Assistant integration (via indoor unit)
• Gold Fin® anti-corrosion outdoor coating
• Quiet inverter rotary compressor & low outdoor sound rating
• Auto restart, timer, and system protection features

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Specifications

Performance
BTU Capacity	18,000 BTU
Coverage Area	Approx. 500–800 sq. ft.
SEER2	21.2
HSPF2	11 / 8.5
Heating Operating Range	Down to –22°F
Cooling Operating Range	Low ambient capability (Hyper Heat series)
Compressor Type	Rotary Inverter
Sound Level	58 dBA

Electrical
Voltage	208/230V (double pole breaker required)
Phase	1
Frequency	60 Hz
Minimum Circuit Ampacity (MCA)	19 A
Max Fuse / Breaker	25 A (double pole)

Refrigeration & Piping
Refrigerant Type	R-454B
Factory Charge Volume	52.21 oz
Line Set Included	25 ft QuickConnect® pre-charged line set
Maximum Line Set Length	75 ft
Liquid Line Size	1/4"
Suction Line Size	1/2"
Metering Device	Electronic Expansion Valve (EEV)

Dimensions & Weight
Unit Width	35.04 in
Unit Height	26.50 in
Unit Depth	13.46 in
Unit Weight	99.87 lbs

Warranty

• 7-Year registered compressor warranty
• 5-Year registered parts warranty
• Eligible for Limited Lifetime compressor replacement with MRCOOL® Care enrollment

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Frequently Asked Questions

Does it really work in cold weather?
Yes. Hyper Heat models are engineered to maintain strong, usable heating down to –22°F.

Can I install it myself?
Yes. The QuickConnect® line set arrives pre-charged, sealed, and vacuumed from the factory. You do not handle refrigerant or connect gauges. A licensed electrician is recommended for the 208/230V electrical hookup.

What size space does 18K BTU cover?
Typically 500–800 sq. ft., depending on insulation, ceiling height, sunlight, and window/door count.

Can I use this with a 115V air handler?
No. This condenser is 230V only and must be used with compatible MRCOOL DIY 230V air handlers or ceiling cassettes.