May 18, 2022
It is very important to size your HVAC equipment properly. Whether it’s for cooling or heating, a heat pump is an excellent way to make your home comfortable and increase its energy efficiency. But for the heat pump to actually work properly and save you money, it must be sized appropriately for your home.
How do you know what size (BTU) your home needs?
Lets find out below.
Undersizing a heat pump is a big mistake. The unit will not be able to heat or cool your home when the unit is under pressure from extreme temperatures. The heat pump will run non-stop on the colder days and end up being much less efficient, this will cause your energy bills to skyrocket. Not what you were looking for when you transitioned to using a heat pump.
I'll have more than enough capacity to heat and cool my home. That's not a bad thing, is it?
Up front cost. The larger the heat pump, the bigger the price tag. If you over size your heat pump, you're just wasting money.
The results will be felt more on the cooling side. The heat pump will cool the air in your home very quickly but what it is actually suppose to do is, gradually cool the air, while simultaneously dehumidifying the air. This makes for a very comfortable interior climate. If your heat pump is oversized, you will have a cool, but damp climate. This can be very uncomfortable. Think cold cellar, or concrete basement.
Another negative result of oversizing is short cycling. The unit will come on and off more frequently. Lower for longer is a fun saying in the trade. The dream operation of a heat pump.
If the unit runs for short bursts, and is constantly turning on and off, its hurting all of the components and the unit will have a shorter lifespan. Undersizing a heat pump is a big mistake. The unit will not be able to heat or cool your home when the unit is under pressure from extreme temperatures. The heat pump will run non-stop on the colder days and end up being much less efficient, this will cause your energy bills to skyrocket. Not what you were looking for when you transitioned to using a heat pump.
Here in Canada, heating needs take priority over cooling. Remember, oversizing the cooling will leave you with a system that cant dehumidify your home so its best to size your heat pump based on the cooling requirements. Heat pump efficiency on the heating side drops with the temperature. So sizing your unit based on your heating needs isn't practical. Rule of thumb is that you need to meet 125% of your cooling needs to determine the capacity of your heat pump. This has been determined to be the best and most efficient way to size your heat pump. When determining your homes cooling needs it's important to understand your homes heat loss. How old are the windows? How well insulated is the house? How leaky is the house?
Central heat pumps are measured in tons of cooling, where one ton equals 12,000 British Thermal Units or BTU for short. This is approximately one ton per 750 square feet for an older Toronto home or 1000 square feet per ton for a modern home. It is important not to include your basement when determining the size of your home.
If you live in a house that is 1500 square feet built before 1994, you will need a heat pump of at least 2 tons, maybe even 2.5 tons if there are many old windows or poor insulation. The best thing you can do is to have a trustworthy contractor come to your home and size the equipment for your specific circumstances.
There are programs in Ontario to help home owners make the transition from natural gas burning appliances to heat pumps. These programs range from grants of up to $10,000 to interest free loans up to $20,000. Look to your local heat pump installer, or your gas provider for more details.