Above Ground Pool Heaters

Above Ground Pool Heaters

SmartPool Sunheater pool heater

All pools, unless it’s a paddling pool, need a source of heat. Otherwise, the occupants will find the water temperature to be uncomfortably cool too cold and will result in an abbreviated experience.  Some basic facts for you to research further when contemplating above ground pool heaters are listed below:

Above ground pool heaters are rated in British Thermal Units (BTUs).  The definition of a BTU is how much thermal energy it takes to heat one pound of liquid one Farenheit degree at 39 degrees F.  Most above ground pool heaters can be in the 100,000 to 130, 000 BTU range, significantly smaller than for inground pools.  It really depends upon the size of your pool and the gallons of water that it contains. Below are formulas that you can use to determine the number of gallons in your pool, and a chart to guide you in ascertaining how many BTUs you will need to heat it :


How Many Gallons of Water in a Pool

for square or rectangular pools:  length x width x average depth x 7.5 = gallons in pool

for oval pools:                                length x width x average depth x 5. 9

for circular pools:                          diameter x diameter x average depth x 5.9


How Many BTUs to Heat a Pool

100 – 200 BTU heaters1,000 gals to 10,000 galsup to 300 sq ft

200 – 300 BTU heaters10,000 gals to 20,000 galsup to 500 sq ft

300 – 400 BTU heaters20,000 gals to 40,000 galsup to 800 sq ft

400 BTU heaters 40,000 gals to 80,000 galsup to 1200 sq ft

It is of note that inground pool heaters can be used to heat above ground pools as well.  They can significantly lower heating times in the event that you have your pool temperature on a thermostat that you turn down after a swim session.  For instance, a Hayward H100 model can increase water temperature in a 15 ft round 5300 gallon pool by 15.2 degrees in an 8 hour time period, but only 4.8 degrees rise in a 27 ft round 17000 gallon pool

Higher BTU rated pool heaters will heat quicker, and have lower operating costs as they are more efficient than lower BTU heaters, but they have a higher front end purchase price. Industry dominate brands for above ground pool heaters are Hayward, Pentair., and Raypak. All three have the advantages of being small and easy to install.  Specific models like the Hayward H100ID and the Pentair Minimax generate 100,000 BTU compared to the Raypak’s 130,000 BTU.  But there is more to a heater than footprint and BTUs.  As you will discover, there are different techologies from which to choose.


Above Ground Pool Heater Types

Gas Pool Heater

Natural gas is a proven safe and efficient method of heating homes.  The same principles apply to heating your above ground pool with natural gas.  Gas heaters raise water temperatures quickly, but they are on the pricey side of the heating equation.  There are cheaper alternatives out there to chose among.

Most natural gas heaters connect directly to your home’s existing gas line and are simple to install and use. Propane pool heaters, conversely, do not have to be hooked up to the existing propane line and are self-sufficient and to install as well.  Propane tanks however must be refilled on a consistent basis.  You BBQ grillers out there, you know how inconvenient it is when the gas runs out in the middle of a grilling session.

Digital propane pool heaters run automatically after you set your desired water temperature, just like a thermostat in your home heating and air system.

There are less expensive manual options that will work just as efficiently with a bit more interaction from the owner. Both natural gas and propane gas pool heaters run about the same for the unit itself.

Above Ground Pool Heater

Hayward H150FDN Universal H-Series Low NOx 150,000 BTU Natural Gas Residential Pool and Spa Heater



Heat Pump Pool Heater

Heat pump pool heaters utilize two types of energy.  First is electricity, which costs you money.  The second is solar energy which heats up the ambient temperature of the surrounding air.  The heat pump pool heater works like a refrigeration unit and draws in the outside air and uses it’s heat to apply to the pool water.  It can work in reverse in climates where it is very hot and the nighttime ambient air temperatures can be used to cool down the pool water temperature.  Once you get into cool climes around 50 F degrees, and the temperatures are below what you would like your pool water to be, the heat pump pool heater loses it’s effectiveness.

Heat pumps are available from 50,000 to  150,000 BTU sizes.  As a general rule, plan on 50,000 BTU of pool heat pump for every 10,000 gallons of pool water. They are cheap to operate but slow to heat pool water, adding 5 to 9 degrees F daily.  A pool cover can help immensely to retain the heat, especially used at night.  In warm temperatures they can cost no more than to operate a 100 watt light bulb!  Even at cooler temperatures a heat pump pool heater can be cheaper than natural gas to operate.  However, they will cease to warm the pool water when the air temperature drops to the mid-50s F.

As compared to gas heaters, pool heat pumps are quiet, clean and much cheaper and safer to operate, but on the downside, they are slow to heat (5-9 degrees per day), and won’t operate at all during cold outside temperatures.

Above Ground Pool Heater

Hayward HP21104T HeatPro Titanium 110,000 BTU AHRI Residential Pool Heat Pump


Solar Pool Heater

Above Ground Pool Heaters

Costway Solar Dome

Solar power has some advantages and some disadvantages as a heating system for your above ground pool.  A great advantage is that continuing costs are basically nil.  The sun provides the heat collected by your system.  Once you have made your investment in the equipment, the sun does the rest.  Another advantage is that it doesn’t get much greener than solar power applied to pretty much any application, including heating your swimming pool.  There are no contributions to the carbon footprint other than what you have already built in to your circulating system.  A lack of noise pollution is another green factor behind utlizing solar power as your pool heater system.  Solar panels are totally receptive.  There is no sound of any other equipment operating other than your pool pump which would be moving water anyways, solar power or not.

Above Ground Pool Heaters

Intex Solar Heater Mat

The disadvantage is that you can’t always rely on the sun.  If you have cloudy or cool and rainy days, your solar power contribution to the pool heater system will be zero.  Therefore, many pool heater systems utilize solar power as a supplement to another mode of heating.  Another disadvantage is that the solar panels are not the most attractive addition to your pool environment.

Sizing A Solar Pool System

Here are the factors impacting your plan for installing a solar pool heater system.

Length of swimming season / Average regional temperature / Pool Size / Desired Pool Temperature / Amount of Sunlight Resource / Collector Installation Orientation / Collector Tilt / Collector Efficiency / Use & Efficiency of Solar Pool Cover.

A basic rule of thumb for determining how many solar panels your pool heating system will require is that they should cover from 50 – 100% of the square footage of your pool.  As mentioned above, this also depends upon the length of your pool season and the temperatures   In addition to the 50% minimum rule, the amount of direct sunlight your solar panels receive will impact the effectiveness of the system.  Obviously, the more direct sunlight the better.

As mentioned in an earlier section, blocking the wind minimizes pool heat loss. Finally, the collector efficiency increases with a sensor system that senses when the temperature in the panels is significantly greater than the water in the pool.  The sensor causes a bypass valve to open, pumping the water stored in the solar collectors into the pool.  The solar controller bypasses the panels during cloudy periods and night time hours, unless you are in a region where pool temperatures become too hot. In that case, a solar controller can send water to be cooled in the panels on cloudy days, or at night.


 Heat Your Pool Efficiently
Think of your above ground pool as a big hot tub.  You should cover the pool just as you do a hot tub.  This not only keeps your pool cleaner from debris, but covers it from wind.  Wind takes away heat from a body of water very quickly and efficiently.  As well, if you keep a solar cover on your pool that will help contain the heat, and even heat it up somewhat.
Your heater thermostat should be controlled and explained to all users in your household.  Cranking up the heat to max a couple of hours prior to using the pool only stresses your heating unit and won’t have increase the speed of heating your pool.  However, forgotten and not turned back down it will overheat your pool eventually and that is expensive!

Plan your pool activity!  At our house we keep the hot tub temperature at 85 F in between dips.  We plan our hot tubbing in advance and go out and move the thermostat up to 94 F, which we know will take approximately 3 hours to achieve.  If you are not using your pool for days at a time, turn down the thermostat the same 10 or more degrees.  If you won’t be using the pool for extended periods, for instance when you are on vacation away, turn the heater completely off.

There are programmable devices that allow you to control the heat in your pool by timer or in real time remotely.  Consider applying such a device to your pool system.  It will save you money in the long run!