How to Heat a Pool: Types of Pool Heaters

If you’re wondering how to heat a pool, you’ve probably been looking around at all the different types of pool heaters on the market. Each one has its own strengths and weaknesses, so deciding which one you want for your pool can be time consuming and confusing. Once you understand how each system works, you can finally make a decision and be one step closer to a warmer pool and an extended swimming season. Read on to learn about the types of pool heaters and how they work.

Gas Pool Heaters

Gas pool heaters, or liquid propane heaters, can heat up your pool in a short amount of time depending on the climate and your pool size. Although they may heat your pool quickly, they greatly increase your utilities bill due to the amount of gas it takes to heat the pool. Gas heaters are commonly used for spa heating or small therapeutic pool heating.  They can be used for occasional pool heating, but most homeowners only heat their pools once or twice with gas.  Once they see the gas bill for heating the pool for a weekend, the gas heater is permanently shut down or used solely for spa heating.

The installed price of a gas heater is approximately 35% less than the cost of a heat pump or solar heater.  The cost of operation, however, is much higher than both.

Heat Pumps

Heat pumps use electricity to transfer heat from the environment to your pool.  The most popular type of heat pump is an air-source heat pump, meaning it gets heat from the ambient air.  Heat pumps can heat your pool with less energy than gas or resistive heaters when the air is warm or cool.  They become less efficient or ineffective when air temperatures get too cold (e.g. below 50F).  Much like solar systems, heat pumps can be used in reverse during hot summers to cool the pool.  

Installing an air-source heat pump costs about the same as a solar pool system, but more than a gas heater.  They operate more efficiently and affordably than gas heaters, but still incur significant electricity fees to heat a pool. This is why many pool owners opt for a combo system of a heat pump along with a solar system.  The solar system keeps the pool continuously warm using only the sun’s energy, and the heat pump is only used once in a while when the weather is uncooperative for an extended period of time.    

Air-source heat pumps work in the same way as a heat pump central air conditioner. It captures the heat from air temperature and turns it into water heating. A compressor pressurises a gas, which heats it up.  This energy is delivered to the pool water as the water travels through a heat exchanger.  A decompression valve, then releases the pressure of the cooled gas, which makes it colder than ambient temperature. The gas then absorbs heat from the ambient air, after which the compressor pressurizes the gas again to heat it up and start the cycle again.   

Geothermal heat pumps operate using the same compression/decompression cycle described above, but instead of using heat from the ambient air, they use heat from the ground or a body of water nearby like a lake.  These are more efficient than air-source heat pumps, especially when air temperatures drop below the temperature of the ground or the body of water.  These systems, however, cost two to three times as much as an air source heat pump or a solar pool heater.  

Electric Resistance Heaters

Electric resistance heaters are generally the most expensive way to heat a body of water, because they require a large amount of electricity to heat. They’re primarily used for heating spas and small therapy pools when other heating options are outside of the budget or are not practical.

This type of heater uses electric currents to create heat. When a current is applied to the resistor inside the unit, the resistor heats. When the water washes over the resistor, it absorbs that heat.

Solar Pool Heaters

A solar pool systems costs about the same as an air-source heat pump, but they have virtually no operating costs to operate.  Not only do they eliminate pollution emissions, but they also immensely reduce your energy bill, as opposed to the other heating options. Solar pool heaters are used for homes that regularly utilize their swimming pools recreationally. Because they use your existing pump and free energy from the sun to heat your pool, they continuously heat the pool with virtually no operating costs. You don’t have to plan ahead and remember to heat your pool. During the swim season, your pool is ready when you are.

Solar heaters are solar panels or collectors used to transfer heat from the sun to your pool. Your pool water circulates through the solar collector, located on your roof or somewhere in your yard where they can be reached by the sun, and as the water passes through the panels, it heats up. Then the heated water is pumped back into your swimming pool.  In residential applications, no second pump is needed.  An automatic valve simply diverts the filtered water to the solar panels before returning to the pool. Due to the siphoning effect, this diversion puts little to no back pressure on the pump.

Hopefully now you have a lot more information about swimming pool heaters than you did before. Knowing the advantages and disadvantages of each heater can be helpful to you when making the decision to buy one. If you’re still undecided about which heater is right for your pool, contact Superior Solar today. We can help you evaluate your options and give you a quote on a pool heating system for your home!