When it comes to cooling an entire house, homeowners often wonder if a single mini split air conditioner is up to the task. Mini splits, also known as ductless air conditioners, offer efficient cooling for spaces up to 700-800 square feet. But can one unit realistically handle a larger home’s cooling needs? Here’s a look at the key factors to consider.
What is a Mini Split AC?
A mini split air conditioner is a type of ductless heating and cooling system. It consists of an outdoor compressor/condenser unit connected by refrigerant lines to a slim, wall-mounted indoor unit installed in the room you want to cool. The indoor unit quietly distributes cooled air without the need for ductwork. Mini split systems are extremely energy efficient and allow you to selectively cool only occupied spaces.
Mini Split Cooling Capacity
Mini split air conditioners are available in a range of cooling capacities, typically from 9,000 BTU to 36,000 BTU. The higher the BTU, the greater the cooling power. A small bedroom or office needs only 9,000-12,000 BTU. A large open concept living area may need 18,000-24,000 BTU or more. The key factors determining proper mini split size are:
- Room size
- Windows, sunlight exposure, and insulation
- Occupancy and usage
- Climate and local weather
Most manufacturers provide sizing calculators on their websites to help you select the appropriate mini split unit for each room you want to cool.
How Many BTUs to Cool a House?
As a very general rule of thumb, you need about 20 BTU per square foot for adequate home cooling. So for a 2,000 square foot house, a cooling system with around 40,000 BTU total capacity would be needed. This could potentially be achieved with:
- One large 36,000 BTU mini split
- Two 18,000 BTU mini splits
- Three 12,000 BTU mini splits
- Or a combination like one 24,000 BTU and one 18,000 BTU unit
Mini splits are designed to cool contiguous spaces up to 800-1,000 square feet. For a typical 2,000 sq ft single-story home, two properly sized 18,000-24,000 BTU units would generally provide sufficient cooling. But there are some caveats.
Factors Impacting One Mini Split for Whole House
Here are some important considerations when relying on one (or limited) mini splits to cool an entire house:
Open Floor Plan
For open concept spaces, a single large mini split is often adequate. The open air flow allows the unit to effectively reach up to 1,000 sq ft when sized appropriately. This assumes adequate insulation and shading.
Multiple Closed Rooms
When a home has lots of closed doors and small rooms, one mini split will struggle to cool the whole space. Multiple smaller units are better suited for efficiently cooling individual rooms.
Insulation
Poor insulation makes cooling more challenging and energy intensive. Ensure the home has proper insulation and sealed air leaks for the mini split to work efficiently across larger areas.
Window Efficiency
Poorly insulated windows and lots of direct sun exposure also drive up cooling demands. Consider window treatments and upgraded glazing to assist the mini split.
Occupancy
The number of people and pets at home impacts cooling needs. Oversizing the mini split helps accommodate greater occupancy. Home offices and other sporadically occupied rooms may need supplemental spot cooling.
Appliances and Electronics
Heat generating appliances like large TVs, computers, and ovens/ranges make cooling more challenging. Cookware, lights, and other electronics add heat too. A larger mini split or multiple units may be beneficial.
Climate Conditions
Homes in very hot southern climates need more cooling capacity compared to temperate northern areas. Size the mini split accordingly.
Zoned Cooling
For the most effective and efficient cooling of an entire house, most HVAC pros recommend a zoned system. This uses:
- Multiple mini split units
- Dampers to control air flow
- Individual thermostats for each zone
Zoned systems allow you to customize cooling and airflow for individual rooms. Closed doors don’t impede air circulation to other areas of the home. You only cool rooms that are occupied, saving energy. This is the ideal setup for whole home cooling using mini splits.
Alternatives to Mini Splits
While mini splits are very efficient, there are some alternative options for cooling an entire house:
Central Air Conditioning
A central air conditioning system with ductwork throughout the home can effectively cool up to 3,000-4,000 square feet. Since air flows freely throughout the house, closed interior doors aren’t an issue.
Evaporative Coolers
In hot, dry climates, evaporative coolers, sometimes called swamp coolers, can be a low-cost cooling solution. They work best with open floor plans and require proper humidity control.
Geothermal Heat Pumps
Though expensive to install, geothermal heat pump systems provide extremely energy efficient whole home heating and cooling between 3-6 tons (36,000 to 72,000 BTU).
Window Units
For spot cooling supplemental areas like home offices, window air conditioners can be an affordable DIY option. Just ensure proper sizing and electrical circuit capacity.
One Powerful Mini Split?
Rather than multiple smaller units, some homeowners consider using one oversized and powerful mini split to cool a whole house. There are a couple issues with this approach:
- Oversized units cost more up front.
- Large units cycle on and off frequently, reducing efficiency.
- They struggle to remove humidity, resulting in clammy feel.
- Cold spots and uneven cooling are common in distant rooms.
It’s better to use properly sized units in a zoned system. This provides better comfort and allows you to only cool occupied spaces.
Home Layout Considerations
The layout and features of your home also impact whether one mini split can sufficiently cool the living spaces. Factors to consider include:
Number of Stories
Mini splits work best when installed on each floor of a multi-story home. Running ductwork between floors for one central unit reduces efficiency.
Open vs. Closed Floor Plan
Open concept homes allow air to circulate freely and require fewer, larger mini splits. Multi-room closed floor plans need more compact units placed in each space.
Vaulted Ceilings
Soaring vaulted ceilings increase the cubic volume a mini split must cool. Oversized units or multiple systems may be needed.
Bonus Spaces
Finished basements, attics, garages, and additions often need supplemental spot cooling beyond the main living areas.
Outdoor Living Areas
Covered patios, sunrooms, and enclosed pool areas also benefit from dedicated mini split units.
Operating Cost Considerations
When deciding how many mini splits to install for whole home cooling, also factor in long term operating costs. Key variables include:
Energy Efficiency
Properly sized mini splits are extremely energy efficient, especially when used in a zoned system. This saves significantly on electricity costs versus central air.
Occupancy Patterns
Zoned systems only cool occupied spaces, providing savings when rooms are unused. Smart controls and timers further optimize efficiency.
Electricity Rates
The cost per kWh varies greatly by region, provider, and time of use. Factor this into the operating costs of running multiple mini splits.
Maintenance
More units mean more filters to change and occasional repairs. But the maintenance on mini splits is relatively minimal overall.
Tax Credits and Rebates
Energy efficient mini split systems may qualify you for rebates, tax incentives, and utility credits in many areas. These help offset purchase and installation costs.
Mini Split Location Tips
Proper placement of mini split indoor units is key to effectively cooling the whole house. Consider these tips:
- Locate high on walls or ceilings for best air distribution.
- Position to avoid having furniture block airflow.
- Direct vents away from windows to minimize heat gain.
- Keep indoor and outdoor units connected via short, direct lines.
- Install outdoor condenser unit in shady, well-ventilated area.
Consult manufacturer guidelines for optimal mini split positioning recommendations.
Professional Installation
Given the complexity of assessing home size and layout, cooling needs, zoning, and mini split sizing and placement, it’s highly advisable to have a professional HVAC contractor install your system for whole house coverage.
An experienced technician can:
- Accurately size and select the proper mini split models.
- Determine optimal equipment placement and configuration.
- Install the units correctly for maximum efficiency.
- Offer expert maintenance and service when needed.
This helps ensure your mini split system will cool your entire house efficiently and effectively for years to come.
One Mini Split: The Bottom Line
Can a single mini split air conditioner cool an entire house? In some cases, it may be possible if the home is on the smaller side, the layout is fairly open, and the unit is substantially oversized. But there are downsides to this approach.
For ideal whole home cooling using mini splits, most HVAC professionals recommend installing multiple, properly sized units in a zoned system. This allows you to efficiently cool only occupied spaces, maximizing comfort and energy savings. With good design and professional installation, mini splits can be an excellent ductless cooling solution for your entire home.
FAQ
How many BTUs are needed to cool a house?
As a general guideline, you need about 20 BTUs per square foot of living space. So a 2,000 square foot home would need around 40,000 BTUs of total cooling power. This could potentially be handled by two 18,000 BTU mini splits or similar combinations.
Will one 24,000 BTU mini split cool my whole house?
A 24,000 BTU mini split may be able to cool an entire small 1,200-1,500 square foot ranch style home, especially if the layout is fairly open. But for larger, multi-room houses, multiple smaller units in a zoned system are usually better.
What size mini split is needed for a 2,000 sq ft house?
For a 2,000 square foot home, a combination like two 18,000 BTU or 24,000 BTU mini splits would provide sufficient cooling capacity. Bigger is not necessarily better – multiple properly sized units provide better comfort.
Will one 18,000 BTU mini split cool a 1500 sq ft house?
A single 18,000 BTU mini split may be able to cool a 1,500 square foot home intermittently. But performance would be marginal on hotter days. Two smaller 12,000-15,000 BTU units would provide much better overall cooling.
How many zones are needed for a 2000 sq ft house?
A typical 2,000 square foot home would generally need a minimum of two zones – one for each floor if it’s two levels. Separate zones for bedrooms, living spaces, and bonus rooms provide optimal comfort and efficiency.
