Heating Options For Your Pool


The greatest luxury that you can add to your home is a pool. Taking a cool dip in the summer heat is like having a private oasis in your backyard, and the paradise is only complete with a pool heater to warm the waters for evening swims and star-lit soaks.

You’ve invested a lot in your backyard getaway, so you are going to want a top-line heater to go with your investment. How do you know which heater is best for you? How do you know which type of heater will fit your luxury needs? We can help you by going over how each type of pool heater works so that you can make the decision for yourself.


Pool heaters are used to heat spas and hot tubs along with in-ground and above-ground pools. They can use gas or electricity to power them. Energy fueled by the pump along with energy from friction can both attribute to the heating pool water. The friction is indirect energy that can also be used when the heater is off, helping you save on energy costs. Some pool heating systems are designed with this energy-saving in mind. The operation and energy efficiency of each heater varies with different kinds of heaters.


The type of heater you choose will depend on your energy-efficiency needs and system preferences. It will also be heavily reliant on the energy resources available to you. For better understanding, let’s go into more detail about types of pool heaters and how they work.


Heat pumps don’t generate heat but rather capture heat to move it to the desired area. The fan draws in water and circulates it through the filter to the heat pump. The heat pump has an evaporator coil that contains chemical refrigerant, which evaporates into gas when heated. The heated refrigerant is then passed to the compressor where its temperature is increased to hot gas and directed to the condenser. The heat from the condenser is transferred to the cool pool water, cooling the refrigerant and warming the water. The now-warmed pool water is circulated throughout the pool and the refrigerant, now cooled back to liquid, passes back to the evaporator coil to repeat the process. Higher efficiency heat pumps often use “scroll” compressors.


Pool heat pumps are rated by BTU (British thermal unit) output and horsepower (hp), with standard sizes ranging from 3.5 hp/75,000 BTUs to 6 hp/125,000 BTUs. To guarantee energy savings and system efficiency, it is important to have a professional size of your heat pump system to make sure that you don’t buy an oversized or undersized system. Pool heat pumps are sized by these factors:

  • The surface area of the pool
  • Difference between the average pool and average air temperatures
  • Wind exposure
  • Humidity levels
  • Cool night temperatures


Heat pump efficiency is determined by the outside temperature of the air. More energy is needed to heat a pool when the outside temperature is lower. Efficiency is guaranteed as long as the outside temperature is no lower than the 45 to 50 degree Fahrenheit range. The coefficient of performance, or COP, the number is the indicator of a heat pump system’s energy efficiency. It can be tricky to truly tell the energy efficiency of a system because no standardized testing exists for the COP of a system. Comparisons are difficult to make unless you are comparing systems within the same manufacturer that used the same test for different models.

COP measurements are typically derived from testing the heat pump with both the outside temperature and the pool water temperature at 80 degrees Fahrenheit. Measurements put a system efficiency at 3.0 to 7.0 (300% – 700% efficiency), meaning that for every unit of energy used, the heat pump produces 3 to 7 units of heat.


Gas heaters use natural gas or propane and are the most popular pool heaters. The heater circulates pool water through a pump where water is filtered before heated. These heaters generate heat by burning gas in the combustion chamber and then transferring that heat to the pool water before pumping it back into the pool.

Gas heaters can heat your pool in any weather or climate and are efficient at heating the pool quickly, which can come in handy if you don’t use your pool often.


Remember to hire a pool professional to size your pool to guarantee accuracy and efficiency for your needs and preferences. Gas pool heaters are sized by the same factors as electric heat pumps and are rated by BTUs, ranging from 75,000 to 450,000 BTUs.


For gas heaters, efficiency is measured by the ratio of usable output to energy input. That means that for an 80% efficient gas heater, the heater produces 80 units of heat to every 100 units of energy. In this scenario, 20 units of energy (fuel) are lost in the heating process. Efficiency ratings are determined by a standardized test and are displayed on heater nameplates, with some ratings as high as 89% to 95%.


Solar pool heaters pump water through a filter to the solar collector, which is a device that the water is circulated through to be heated by the sun before it is returned to the pool. Sensors and valves can be added to solar heating systems to divert water when the collector temperature is much higher than the pool water temperature. If the collector temperature is near the same as the pool water temperature, the water is bypassed and returned to the pool.

Solar collectors are made out of different materials:

  • Unglazed collector: These are usually made of strong rubber or plastic treated with a UV light inhibitor. They do not include glass coverings (glazing) and are more ideal for pool usage during temperatures above freezing.
  • Glazed collector: Glazed collectors tend to be more expensive because of the materials it takes to make them. They are made of copper tubing on an aluminum plate, which is covered with iron-tempered glass. These collectors work with heat exchangers by transferring fluids to work more efficiently at capturing heat in colder weather.

Things to Consider:

  • Determining your site’s source of solar heat is important to do before purchasing a solar heating system. Solar system installers can perform a solar analysis to see if your site gets enough direct or diffused sunlight to be able to install a solar heating system.
  • The location of your solar collectors should be oriented to get the maximum amount of exposure to solar power. You should take into consideration the orientation of your roof and other properties of your landscape and weather. The most efficient direction for your collector to face if you are in the northern hemisphere is true south.
  • Solar collectors should be tilted to an angle determined by the latitude of your site and how long during the year you will be using your heated pool. You will also want to consider the angle of your roof if you plan on mounting your collectors on the roof.


Efficiency for solar heating is determined by the system’s thermal performance rating, which is measured by BTUs per square foot per day. Higher efficiency systems will have a higher number rating. High-efficiency systems may need fewer collectors and save you more on energy costs.


Solar pool covers use energy from the sun to heat your pool and can be cost-efficient by saving energy while keeping your pool clean and heated. Most pools collect the sun’s heat on their own, but evaporation and wind can make the pool lose that heat. Solar covers prevent evaporation heat loss and also have bubbled tops that act as a magnifying glass to increase the heat captured from the sun.

Types of Covers

These solar covers come in different colors that identify their thickness measured in mil, which is one-thousandth of an inch.

  • Blue covers can be 4 mils, which typically lasts about a year before falling apart, or 8 mils which can last one to two years.
  • Clear covers measure 12 mil, which lasts three to four years, or 16 mil which is the most durable, lasting up to ten years. Clear covers also allow for sun heat to absorb more effectively.


Solar pool covers not only keep debris from blowing into your pool, but they also reduce your water loss by 40% and can keep your pool water up to ten degrees warmer. Most pools without a cover can lose up to 60% of their heat to evaporation and 30% to radiation.


Now that you know a little more about pool heaters. You can effectively decide which heater will best suit your needs. If you live in a warmer climate, a pool cover or solar heating might be enough. If you like to take winter soaks in the spa when it snows, a gas heater might work better for you. Either way, be sure to consult a professional pool installer to get as much information about your needs and energy availability before you make your final decision.