The best heat pump size for your home or business depends primarily on the area you need to heat or cool. Mini-split heat pumps are ideal for one to a handful of rooms, multi-family residences, or relatively small areas that simply require supplemental heating or cooling.

When people talk about “sizing” a heat pump, especially ductless heat pumps, they frequently speak in terms of British thermal units (BTUs). A BTU is technically the amount of energy it takes to increase the temperature of a single pound of water by one degree. The per-hour heating outputs of ductless heat pumps generally range from 6,000 BTUs to 24,000 BTUs.

Discussions on heat pump size aren’t about the actual physical size of the outdoor condenser/compressor unit and the indoor evaporator/blower unit. The term “sizing” is usually used in reference to the act of calculating the heating or cooling output needed to control the temperature in an area. 

For example, if you want to control the temperature in a 400 to 500-square-foot space you might want to invest in a heat pump that’s between 10,000 and 12,000 BTUs per hour. You can determine the approximate heat pump size you’ll need by multiplying the square footage of a room by 25 to get a rough baseline BTU output.

Although this simplified calculation can give you a ballpark idea of what size heat pump you might need, it’s not exactly scientific or adjusted for Maine’s climate and your specific home. You should always speak with a local heat pump expert experienced with properly sizing mini-split systems in the Bangor area before making any purchases.

Factors Other Than Square Footage that Should Affect Ductless Heat Pump Sizing

If your heat pump installation contractor is making their recommendations on heat pump size based solely on the square footage of your home or business, they are likely not doing their due diligence. Two other important variables for Maine home and business owners are cubic volume, which requires accounting for ceiling height and square footage, and insulation.

With our cold winters, your home or business’s insulation, as well as weather sealing or the quality of your windows, can have a significant impact on how hard your heat pump needs to work. Your heat pump installation specialist can make recommendations based on those factors. For example, they may recommend adding an extra 20 percent on BTUs per hour for poor insulation or rooms with particularly high ceilings.

In businesses where people could be frequently entering and exiting a store or office, it may be necessary to add even more BTUs per hour.

It’s generally not possible to predict all the variables that will affect your heat pump size calculation without a free in-person heat pump installation estimate. The team at Valley Home Services can come out to your business or home, consider all the factors that could enhance or detract from your heat pump’s temperature control performance, and suggest heat pump size options that will work for you.  

How Is Heat Pump Sizing Different from Air Conditioner and Furnace Sizing?

When HVAC companies consult with their prospective clients on central air system design, they often talk about size in terms of tonnage instead of BTUs. Tonnage is the measure of the volume of air that can be removed from inside the home or business in an hour. Since mini-split ductless heat pumps work on a much smaller scale, their size (or heating and cooling output) is measured in BTUs.

If you’re looking for a reference point, one ton in HVAC size equals roughly 12,000 BTUs.

How Many Rooms Can a Mini-Split Heat Pump Heat or Cool?

Many mini-split heat pumps can heat or cool up to four rooms. You’d generally have a single condenser outside and then a separate evaporator in each room that needs to be heated or cooled. The calculation is the same whether you need to heat or cool one room or four – you’d still base the size on total square footage and cubic space.

Are You Ready to Save Money and Enjoy Better Temperature Control?

Running a mini-split heat pump installed by Valley Home Services as your heating source or using it to supplement the existing heat system in your Bangor home or business can save you money on fuel costs and give you greater control over your comfort.

Ductless heat pumps can be a great option for supplemental heat in rooms or an office where you’re spending the majority of your time. Leave your whole-home thermostat lower and instead rely primarily on your affordable heat pump for comfort.

Learn more about heat pump sizing and installation by calling our mini-split experts at (800) 316-7815.