What Size Pool Heater Should I Get?

March 31, 2021

A child splashing in a pool

It is that time of year when Canadians’ thoughts turn to renovations they are planning for their outdoor activities.

One of the ways you can extend your swim season is to install a pool heater. It would be best if you decided whether you are using a pool heater as early as possible to plan for the installation of its gas line or electrical line, depending on the type you choose to own. 

All heaters are measured in British thermal units (Btu’s) indicating the amount of energy required to raise one pound of water by one degree Fahrenheit.

How do you decide what size pool heater you need?


Two considerations to best choose the proper size pool heater:

1) The size of your pool and your heater’s purposes
2) Your preference of a gas heater or electric heat pump

a spa attached to a pool

1) The size of your pool and the purposes for your heater:

If you have a spa / hot tub attached to your pool, you should opt for a large heater; 400,000 (400k) Btu’s. Your spa, even if it is a large one, will heat up more quickly, probably within an hour with a gas heater; however, the convenience of a gas heater will cost you a bit of money.

Calculating what size pool heater to get:

  • Multiply in feet the average width by the average length of your pool.
  • Divide that number by 3 to get the minimum Btu size heater recommended for that sized pool.
  • If you opt for a gas heater, choose a larger-sized heater, especially if you do not use a solar cover.
  • Is your pool located in an open area exposed to much wind that cools it down?
  • Do you prefer to swim at night, requiring more heat?
  • Are you using a solar cover? It could mean a huge difference in your Btu requirements and how often the pump needs to come on.


 2) Do you prefer an electric heat pump over a gas heater?

An electric heat pump in the right environment (warm outdoor air) is more cost-effective than a gas heater while serving your commitment to not burn fossil fuel in a gas heater.

It has the qualities of both a solar heater and a gas heater. Although it can be a very cost-efficient way to heat your pool, it is for people who do not mind gauging its operation. It works similarly to a furnace, outputting warm air heated in a compressor and passing it through a heat exchanger. The warmer the outdoor air the more efficient and more cost-effective the process. Ambient temperatures lower than 30 degrees Celsius push the demands of an electric heat pump.

A gas heater has the highest Btu output, and as a result, is expensive to run. If you run your gas pool heater without consideration, you could pay hundreds or even thousands of dollars a month extra to keep your pool at a constant temperature. A solar blanket will help with costs.

Canadian pool owners must weigh the costs of extending the pool season with heaters. For many people, their love of relaxing in a warm backyard pool is an easy decision.

Plumbhouse Plumbing Heating and Electrical carry top-of-the-line Canadian electric heat pumps and gas heaters. We hope this information answers some of your questions about sizing pool heaters.

Our technicians can further help you decide the best size pool heater for your specific circumstances. Call us any time.

Published by
March 31, 2021 4:18 pm

Categorised in: