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Your bonus room bakes in July and freezes in January. Central air has never quite reached it. A ductless mini split was built for exactly that.
Filterbuy’s single-zone mini split heat pumps heat and cool any room without ductwork. Finishing a garage? Upgrading a bonus room? Adding climate control to an older home that was never wired for central air? These systems install where running ducts would be expensive, disruptive, or just not practical. They run quietly and operate year-round, using inverter-driven technology that adjusts output continuously rather than hammering on and off like older systems.
Every ductless air conditioner in our lineup includes a wall-mounted indoor unit that’s compact and easy to live with. Choose from three BTU sizes, each available in 115V and 230V configurations, so you can match the right system to your room’s square footage and your home’s electrical setup.
And because this is Filterbuy, we’ve spent more than a decade helping millions of homeowners understand and improve their indoor air. That obsession doesn’t stop at the filter. Every mini split AC system we sell comes with the same air quality knowledge we’ve built since 2013. From the unit to the filter, we’ve got your air covered.
Find the right mini split system for your space. Use the table below to match your room’s square footage to the right BTU output, then pick your voltage.
| BTU Size | Room Coverage | Best For | Voltage Options |
|---|---|---|---|
| 9,000 BTU | 150–350 sq ft | Bedrooms, home offices, small additions | 115V / 230V |
| 12,000 BTU | 400–600 sq ft | Living rooms, studios, master suites | 115V / 230V |
| 18,000 BTU | 700–1,000 sq ft | Large living areas, finished garages, open-plan spaces | 115V / 230V |
A ductless mini split connects a compact outdoor compressor to a wall-mounted indoor air handler. No ductwork required. Refrigerant moves between the two units through a small conduit in the wall, delivering precise temperature control directly to the room.
Central air systems push conditioned air through a duct network, losing energy at every joint and gap along the way. The U.S. Department of Energy estimates that duct losses account for more than 30% of energy consumption in central HVAC systems — energy that a ductless setup keeps in the room where it belongs.
Most mini split systems also function as heat pumps, which means one unit cools in summer and heats in winter. For single-room climate control, it’s one of the most practical and energy-efficient options available.
Getting the BTU rating right is the most important call you’ll make when buying a mini split. Go too small, and the unit never catches up. Go too big and it short-cycles, running in brief bursts that waste energy and let humidity build up. Use the table below to find your starting point.
| Room Size (sq ft) | Recommended BTU | Typical Rooms |
|---|---|---|
| 150–350 sq ft | 9,000 BTU | Bedrooms, offices, nurseries, small studios |
| 400–600 sq ft | 12,000 BTU | Living rooms, master bedrooms, large studios, sunrooms |
| 700–1,000 sq ft | 18,000 BTU | Open-plan living areas, finished garages, lofts, and workshops |
Ceiling height, sun exposure, insulation quality, and local climate can all shift the math. Rooms with large windows, poor insulation, or heavy sun exposure may need a step up in capacity. If you want a precise number, a licensed HVAC professional can run a proper load calculation.
Your voltage depends on what’s already in your home. A 115V mini split runs on a standard household circuit, making it the easier choice for rooms that already have a dedicated circuit. A 230V mini split needs a dedicated 230-volt circuit, similar to what powers a dryer or electric range, but it delivers more stable performance for larger systems.
All three BTU sizes are available in both voltages. If you’re not sure which is right, check your breaker panel or ask your electrician before you order.
Most mini split retailers sell you a box and move on. We don’t.
At Filterbuy, we think about what happens after the install, because clean air doesn’t stop at the thermostat. Here’s what most people miss: mini splits use filters with lower MERV ratings than traditional central HVAC systems. Less filtration by default. Without regular cleaning and replacement, those filters clog with dust, pet dander, and allergens, cutting airflow, driving up energy costs, and compromising the air your family breathes.
That’s where more than a decade of air quality work makes the difference. We’ve helped millions of homeowners understand and improve their indoor air. We know filtration inside and out, and we bring that knowledge to every mini split we sell.
When you buy a mini split from Filterbuy, you get:
Expert guidance on mini split filter maintenance to protect performance and air quality
Access to Filterbuy’s full library of indoor air quality resources, guides, and product recommendations
A partner who stays involved after the sale, not just at checkout
Free shipping on every order
Support from a team that actually knows air quality
Your mini split is only as good as the air it moves. We make sure that air is clean.
A ductless mini split is a compact heating and cooling system built around two main components: an outdoor compressor/condenser and an indoor air-handling unit. A small conduit connects them through the wall, carrying refrigerant, power, and drainage lines. No ductwork needed. That’s why mini splits work well for room additions, converted garages, and older homes where running traditional ducts would be impractical or too expensive.
Mini splits run on a refrigerant cycle that transfers heat between the indoor and outdoor units. In cooling mode, the indoor unit pulls heat out of the room and sends it outside. In heating mode, the process reverses. The outdoor unit pulls heat from outside air and brings it indoors. Inverter-driven compressors adjust their speed continuously, so the system holds precise temperatures without the energy spikes that come from older on/off units.
Yes. Every mini split system we sell functions as a heat pump, providing cooling in summer and heating in winter from a single unit. That makes them a year-round climate solution and a more versatile choice than window air conditioners, which only cool.
Start with your room’s square footage:
150–350 sq ft: 9,000 BTU (bedrooms, offices)
400–600 sq ft: 12,000 BTU (living rooms, studios)
700–1,000 sq ft: 18,000 BTU (large rooms, garages)
Ceiling height, insulation, sun exposure, and local climate can push that number up or down. For precise sizing, a licensed HVAC technician can run a proper load calculation.
Equipment costs vary by BTU size and features. At Filterbuy, every ductless mini split ships free. Professional installation typically runs $1,500 to $4,000, depending on location, electrical requirements, and installation complexity. The upfront cost is higher than that of a window unit, but mini splits deliver substantially lower operating costs over time through better energy efficiency and a longer lifespan.
Yes. Every mini split has a built-in air filter that captures dust, allergens, and airborne particles before they circulate through the room. One thing worth knowing: mini split filters typically carry lower MERV ratings than the filters used in central HVAC systems, so they capture fewer fine particles by default.
Clean your filter every 2–4 weeks and replace it on schedule. Neglecting it leads to reduced heating and cooling performance, higher energy bills, and poorer indoor air quality, especially for anyone dealing with allergies or asthma. As the nation’s leading air filtration experts, Filterbuy can help you stay on top of it.
With proper maintenance, a quality mini split runs 15 to 20 years or more. The key is consistent upkeep: regular filter cleaning, keeping the outdoor unit clear of debris, and scheduling annual professional service. Clean filters do more than most people realize. They protect the system’s internal components, maintain efficient airflow, and help your mini split run at full performance for years.
Very. Because they deliver conditioned air directly to the room without ductwork, they skip the energy losses that ducted systems can’t avoid. Most carry high SEER ratings and use inverter compressor technology, which adjusts output to match actual heating or cooling demand rather than cycling on and off. Keeping your filters clean is one of the easiest ways to hold onto that efficiency over time.
It depends on your home’s electrical setup. A 115V mini split runs on a standard household circuit. A 230V unit needs a dedicated 230-volt circuit, the same type you’d use for a clothes dryer or electric oven. Both are available across all three BTU sizes. Check your electrical panel or ask your electrician before ordering.
Neither is the universal answer. Central air is designed to condition an entire home through a duct network, and it’s a solid option when the ductwork already exists. Ductless mini splits are built for specific rooms or zones, especially in homes without existing ductwork: older houses, room additions, converted garages, and sunrooms. They also avoid the energy losses that come with ducted systems, which often makes them the more efficient choice for single-room or supplemental heating and cooling.
Shop Filterbuy’s full lineup of ductless mini split systems: three BTU sizes, 115V and 230V options, free shipping on every order. And unlike any other mini split retailer, we back every purchase with the air quality knowledge we’ve spent over a decade building.
Questions? Our team knows air.
