Lineset Extension Kit for MRCOOL DIY Split Units

Control your mini split with Alexa or Google Assistant, or remotely with an Android or iOS phone via Wi-Fi. Set schedules and control multiple rooms from anywhere — change your temperature settings from the office or while traveling, as long as you have an internet connection.

Our efficient mini splits are Energy-Star certified. With ultra-efficient ductless air conditioners you can expect to save upwards of 50–60% on your energy bills yearly — a great system for heating and cooling a home or business while minimizing long-term energy costs.

Our Ultra-DC-Inverter technology lets these systems provide cooling and heating at up to −13°F/−22°F with up to 100% efficiency, so hyper-rated models can serve as your primary heat source all year round — even in the coldest climates. The hyper feature is available on most of our mini splits.

Our ductless mini splits include self-cleaning, leak detection and self-diagnostics — all there to keep the system running properly for years. Enjoy peace of mind knowing your mini split will warn you of any equipment problems.

The DC Ultra inverter compressor delivers a superb reduction in energy consumption, making these some of the most efficient systems with DC-inverter technology — it's what pushes mini splits to high SEER2 certifications while minimizing your energy costs.

What BTU/ton for your area?

Use this BTU/ton size chart to size your mini split indoor or outdoor unit.

If you are looking for mini splits, most sellers cover the basics: an outdoor compressor connected to indoor units via small refrigerant lines, high energy efficiency without duct loss, and separate room temperatures — plus the simple setup needing just a small 3-inch wall opening. All true, but there are critical technical details and long-term ownership realities almost nobody tells you before you buy.

Beyond washing your mesh air filters every few weeks, mini splits need a deep chemical cleaning of the internal blower wheel and evaporator coil every 1–2 years. Because the heads recirculate the air in your living space, neglected moisture can breed toxic black mold inside the barrel fan. And while most guides cover summer condensation draining from the indoor head, heat pumps reverse in winter: during freezing weather the outdoor unit sheds gallons of water in defrost cycles — without a base pan heater or proper drainage that runoff freezes solid, destroying fan blades and icing the compressor base.

Finally, budget for electrical and warranty requirements upfront. A multi-zone system frequently requires upgrading your home's main electrical panel — often from 100-amp to 200-amp service — plus dedicated 208/230V double-pole breakers. Most importantly, beware of online DIY claims: almost every major manufacturer explicitly voids your multi-year parts and compressor warranty unless a licensed HVAC technician performs the final nitrogen pressure test, line evacuation, and refrigerant commissioning.