Knowing whether you can save by installing a heat pump is the first step.
The second step is determining what size machine you need.
In this post, we’ll cover how a contractor will decide what size heat pump you need:
- what factors of your home affect the size machine required
- and why a bigger heat pump is not better
Layout of your home
The layout of your home, and where you want to offset your oil or electric heating is the first thing to consider when sizing a heat pump for your home.
For someone who’s looking to only add air conditioning to a master bedroom that’s 300 square feet then a 9,000 BTU sized ductless system is more than enough.
However, that same home that has 750 square feet of open living area on the main level will need a 12,000 or 15,000 BTU sized system.
Below is a rough guide for square footage to BTU sizing. This is not a hard and fast rule but is a good guideline.
9,000 BTU / 300 – 450 sq.ft
12,000 BTU/ 500 – 600 sq.ft
15,000 BTU / 600 – 850 sq.ft
18,000 BTU / 1,000 sq.ft +
Factors that can affect Size Requirements
Homes that have a lot of solar gain (lots of windows that generate heat in the winter and summer) can work to your advantage. In this case a larger area may be able to use a smaller heat pump.
Highly insulated homes that lose very little heat could potentially require a slightly smaller machine than the same sized home that isn’t as well insulated.
Old windows or drafty older homes are the reverse. A slightly larger machine could be required as more heat leaves the home, therefore, it takes more heat to maintain temperature.
Bigger is not always Better
There is some misinformation that the bigger the heat pump the better no matter the size of the space it’s installed in. The truth is the opposite.
Heat pumps are most efficient when they can get a room to temperature and then go on “cruise control” to maintain that temperature. Keeping the set temperature happens only when the machine is perfectly sized to meet the square footage of the space.
Heat pumps draw the most electricity when they first turn on, boot up and begin to change the temperature of the room. As the room gets to temperature, the heat pump ramps down and draws less electricity to maintain the temperature.
If a machine is too large for the space, it turns on, brings the room to temperature very quickly and then shuts off. It never gets to a cruise control mode and is only running in the mode where the most electricity is required.
To avoid this, ensure you have a professional into your home to assess:
- square footage
- and potentially complete a heat loss calculation
This will ensure you get the right sized machine to optimally heat and cool your space for the least amount of electricity.
To receive a written estimate for install in your home give us a call at the number above or submit the form on this page. We’ll arrange a time to come review your home’s layout, current heating system, and electrical service. From there we can make a recommendation on the best machine(s) for your home.