How do I determine the size of heat pump I need for my home?

Whether it’s for cooling or heating, a heat pump will make your home comfortable and increase its energy efficiency. But for your heat pump to work optimally and save you money, it has to have the right amount of power.

How do you determine how many BTUs your home needs? This article answers that question.

The importance of having the correct BTU

Why is it important to calculate the power needed for your home before buying a heat pump?

No one wants to have an appliance that isn’t powerful enough. The unit will not be able to cool or heat your home correctly, and it will be in constant use, which will shorten its lifespan and increase its operating costs.

But what about a unit that is too powerful? It’ll have more than enough capacity to heat and cool your home. What’s the problem?

First, the more powerful a heat pump is, the more expensive it is to buy. So by purchasing a unit that is too powerful, you’d be paying too much for nothing.

Secondly, when a heat pump is in cooling mode, it dries the air in your home while cooling it. A unit that is too powerful will cool the air in record time, but it will not have time to dry the air. The result? A cold and humid air, which feels very uncomfortable.

Third, a heat pump system that is too powerful will constantly be stopping and restarting, which causes premature wear and tear and a shorter lifespan.

Choosing a heat pump with the right amount of power guarantees you savings and comfort. The Legault-Dubois website offers a very informative video (though solely in French) on the subject.

How to determine the power of your unit?

In Canada, heating needs are higher than cooling needs. Since you don’t want to end up with a unit that is too powerful and unable to dehumidify the air in the summer, you have to calculate your BTU requirements based on your cooling needs. Also, the efficiency of a heat pump decreases as the outside temperature drops, so trying to meet all your heating needs with a heat pump wouldn’t be economical.

Natural Resources Canada says that you need to meet 125% of your cooling needs to determine the capacity of your heat pump. This means that if you calculate that you need 20,000 BTU to cool your home, by installing a 25,000 BTU heat pump, your cooling needs are met, and the heating load is between 80% and 90%. The difference can be made up by electric baseboard heaters or any other heating system. This is the best possible combination of performance and cost.

Also according to Natural Resources Canada (NRCan), to determine the required heat pump capacity, refer to the CSA-F280-FM90 standard: Determination of the Required Capacity of Residential Heating and Cooling Appliances.

According to this standard, several factors are taken into consideration to determine how much heat the building loses in the winter and how much heat it gains in the summer. These factors include, but are not limited to: floor area, degree of insulation, level of sunlight and air leakage.

General rules for a rough calculation

As explained above, many factors go into determining which heat pump you should purchase. Still, some general rules of thumb can help you choose the approximate power you need.

For a heat pump or wall-mounted air conditioner, it’s about 1,000 BTU per 100 square feet. So for a 1,000 to 1,200 square foot area, your heat pump would be about 12,000 BTU.

For the same area, if space is limited, the power can be reduced to 9,000 BTU. On the other hand, if the space is an open area, with many windows or high ceilings, the power can be increased to 15,000 BTU.

The single-split wall-mounted heat pump, which has only one indoor unit located in the main room, is ideal for homes with an open area. It generally ranges from 9,000 to 18,000 BTU.

The multi-zone wall-mounted heat pump, which has several indoor units, is recommended for homes with multiple floors or closed rooms. It is usually rated between 18,000 and 36,000 BTU.

Central heat pumps are measured in cooling tons, where one ton equals 12,000 BTU. This is approximately one ton per 750 square feet. So for a house of about 1,500 sq. ft. (excluding the basement and garage), you need a heat pump of at least 2 tons, and maybe even 2.5 tons if there are many windows or poor insulation.

Central heat pumps are generally installed in homes that already have air ducts. They usually range in size from 24,000 to 60,000 BTU.

Other criteria that allow you to measure the efficiency of heat pumps are SEER and HSPF.

Check to see if your unit is eligible for a grant

Some government programs offer grants for the purchase and installation of eligible heat pumps.

The grants available depend on the size of your heat pump. For every thousand BTUs of heating at -8°C, you receive $50 in financial assistance. So for a 10,000 BTU/hr heat pump at -8°C, you receive $500, and $1000 for a 20,000 BTU/hr unit.

These subsidies are available through the Rénoclimat program of Transition énergétique Québec and through Hydro Québec’s Efficient Heat Pump program. The Novoclimat program also offers a grant to the first owner of a new Novoclimat-certified home when an eligible heat pump is installed.

Ask specialized contractors

Since there are so many factors that can influence your choice of unit, it’s best to call on professionals to ensure that you have a heat pump that adequately meets your cooling and heating needs.

These specialized contractors have the skills to evaluate your home’s air conditioning and heating needs.

During an initial visit, MST’s technicians will evaluate, among other things, the size of your home, the number of floors, the height of the ceilings and the level of insulation. These factors allow us to advise you on the most suitable unit for your home and help you make an informed decision.

By doing business with MST, you’ll have a quality heat pump adapted to your needs and installed according to the manufacturer’s strict standards. The result? Your heat pump will last a long time and provide you with optimal performance, giving you peace of mind in the greatest of comforts.