Is Bigger Better? Heater Size: What Matters is Your Choice!

When it comes to selecting a Swimming Pool Heater, let’s face it selecting the size is quite difficult. There are many things to consider, including; the size of the pool (volume), the distance of the heater to the pool, distance the heater is from the gas supply, how fast you would like the water in the pool to heat, wind exposure, night temperatures, and many more.

Types Of Pool Heaters

Let’s make its simple! When selecting your gas heater the rule of thumb is the colder the area of your pool the higher BTU (British thermal Units) output heater you will require! Simple right? Well let’s not get ahead of ourselves. We will need to do a little math to figure out what is perfect for you. Are you ready? Great! Let’s begin.  

The basic formula is for selecting the BTU for your pool heater is = Pool Area x Temperature Rise x 12. See very simple.

Figuring out your pool are is very simply and will most likely come with you pool instructions, if you are not familiar with how to get the area of your pool visit our “Measuring your Pool Article”.

Figuring out Temperature Rise involves figuring out the average temperature for the coldest month of pool use, and subtracting it from the desired temperature.

Keep in mind this formula is based on a an approximate 1 degree Fahrenheit rise per hour , for an increase of 2 degrees multiply the whole product of the formula by 2, And so on so forth.


I have a pool that is 16 feet by 32 feet, I live in Toronto where the lowest month average temperature in the season is, Assuming I will open the pool early May and close it late September my lowest average monthly temperature for the month of May is  43°F. And I would like the temperature to rise 2 degrees per hour and maintain 70°F. The BTU size require for my preferences would be calculated as follows:

  1. Area of Pool = 16 x 32 = 512 feet
  2. Temperature Rise needed = 70°F - 43°F = 27
  3. Finally (512 x 27 x12) x 2 =331,776 BTU

Therefore if I would like to run a 16 x 32 pool in my weather conditions and have a rise in temperature on 2 degrees per hour I require a heater with approximately 330,000 BTU. If I however had preferred a 1 degree increase my BTU requirements would be half (150,000 BTU).

On a side note, most commonly people with pools that either have a pool size of 16 x 32 or 18 x 36 will require a 250,000/260,000 BTU heater. This minor difference is due to the preference in manufacturer. Different manufacturers produce heater at different BTU “intervals”.





Comments (0)

Allowed tags: <b><i><br>Add a new comment: