Combind Energy Services
Combind Energy Services

How To Choose a Gas Heater for your Pool or Spa

Posted by Combined Energy Services on Apr 21, 2016 9:12:49 AM


As the summer quickly approaches, it's the perfect time to think about your pool and how you're going to heat it.  

Nobody likes stepping into a freezing cold pool!  And after making a large investment to your home, you want to get the most out of your home improvements.

Pool or spa gas heaters can have numerous advantages, especially having the ability to extend the use of your pool by 2-3 months.

This guide will take you through the many options to consider when you choose a gas heater.

Gas pool heaters remain the most popular system for heating swimming pools.  Today's models have a much higher efficiency than their older counterparts.  

Step 1: How they work

Gas pool heaters use either natural gas or propane.  As the pump circulates the pool's water, the water drawn from the pool passes through a filter, then through a heater warming it to temperature and finally back into the pool, nice and warm!

They're ideal for heating pools for short periods of time and for quickly heating pools.  

Step 2: Selecting a Gas Heater for your Pool or Spa


When selecting a gas swimming pool heater, consider:

  • Size
  • Efficiency
  • Costs

Step 3: Sizing a Gas Pool Heater

Have a trained pool professional perform a proper pool sizing for your pool to determine the correct pool heater size.

Basically, heaters are sized according to the surface area of the pool and difference between the pool and the average air temperatures.  Other factors include wind exposure, humidity levels, cold night temps.  Homes that experience these other factors may require a larger heater.

Gas pool heaters are rated by Btu (British Thermal Units).  Outputs range from 75,000 Btu to 450,000 Btu.

 Steps to calculate approximate heater size:

  1. Determine desired swimming pool temperature.

  2. Determine average temperature for the coldest month of pool use.

  3. Subtract average temperature from the coldest month from the desired pool temperature.  This will give you the temperature rise needed.

  4. Calculate the pool surface area in square feet.

  5. Use the formula below to determine the Btu/hour output temperature requirement of the heater:

Pool Area x Temperature Rise x 12

Step 4: Determine Efficiency of Gas Pool Heater

Heater efficiency is the ratio of usable output of energy input.  For example, 80%-efficient heater uses $80 worth of useful heat for every $100 worth of fuel.  Therefore, it wastes 20% of the fuel.

The pool heater's manufacturer can provide its efficiency percentages.  Also, most gas pool heaters feature their efficiency percentage on their nameplates.

Today, you'll find some gas heaters with 89% - 95% efficiency.  

Step 5: Estimating Costs and Savings


Step 6: Installation and Maintenance

Proper installation and maintenance of your gas pool heater can optimize efficiency.  It's best to have a qualified pool professional install the heater and perform complicated maintenance or repairs.

While you may not be thinking about the closing process of your pool at the moment, proper maintenance includes winterizing your pool heater as well.  This task includes disconnecting your heater, winterizing the unit and storing in a safe, dry place for the non-pool months.

With proper installation and maintenance, gas pool heaters can last for many years of swimming enjoyment!  


Your pool and spa is a long term investment that you, your family and friends will enjoy year after year.  With a gas pool heater, there's now an easier way to enjoy your investment more often, more reliable and more efficiently throughout the year.  



 Family owned and operated since 1968, Combined Energy Services is one of the largest propane gas and fuel suppliers in the Hudson Valley.

With four offices in operation, CES provides customers throughout the Catskills (Sullivan, Orange County), Hudson Valley (Ulster County), Eastern Pennsylvania (Pike County) and Northern New Jersey (Sussex County) with dependable propane gas, fuel oil and kerosene deliveries, as well as un-matched, around-the-clock repair service.

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