Whether it’s to reduce temperature shock for athletes or simply to create a luxurious tropical swim in your own backyard, the ability to heat a swimming pool is a convenient luxury. The two main types of units typically used to heat both athletic and recreational swimming pools are pool heaters and heat pumps.
Although both systems operate electronically, the major difference is that pool heaters pull from a heating element, whereas heat pumps utilize natural heat in the air to warm the water. Both pool heaters and heat pumps have their pros and cons.
Read on to learn more about how each of these pool heating systems works and how they are different. By the end of this article, you should be able to tell what kind of system is best for your pool.
How Do Pool Heaters Work?
There are a few different kinds of pool heaters, drawing power from differing sources. A traditional pool heater runs on electricity; however, alternative methods of power such as natural gas or solar energy are gaining popularity.
A pool heater essentially works by drawing pool water in, passing it through the heating element, and filtering it back into the main body of the pool. Copper coils within the heating element are brought to temperature by whichever energy source powers the unit.
If the pool heater is powered either by natural gas or liquid propane, the heating unit will be fed by a combustion chamber. Gas-powered water heaters are noted to provide the fastest noticeable difference in water temperature. This is done by supplying a surge of power from the residential gas line, providing immediate warming at a relatively expensive rate.
Gas-Powered Pool Heaters
There are a variety of both benefits and drawbacks, according to AquaCal, which make gas-powered pool heaters a popular option with many pool owners.
Pros
- Rapid water temperature change
- Impervious to outside air temperature
- Moderately low purchase cost
- Relatively quiet operation
Cons
- Poor energy efficiency
- Increasing gas prices make pool heaters pricey to operate
- Gas exhaust is not environmentally friendly
- Relatively short unit lifespan
Solar-Powered Pool Heaters
Solar power has long been recognized as a more energy-efficient and economically sustainable source of renewable energy. Some users choose to heat their pools with units powered by the energy of the sun.
There are a number of downsides to choosing a solar-powered pool heater, however, as listed by Solar Source.
Pros
- Solar energy is free and renewable
- Little no operation cost
- Solar pool heaters operate whenever there is sunlight available
- Unit longevity
- Environmentally friendly
Cons
- More difficult to heat on low-sunlight days/at night
- Higher purchase price
- More time is required to heat
- No “power surge” flash-heating ability
Electric Resistance Pool Heaters
Electric resistance pool heaters function by using electric currents to generate heat. A metal resistor running through the unit enables the heater to rapidly transform the electrical current into heat.
Water circulating in from the pool is heated by the electrical current within the heating element, then filters back out into the body of the pool.
Pros
- Effective for heating small volumes of water, such as jacuzzis, spas, and therapy tubs
- Low purchase price
Cons
- Expensive installation process
- Poor energy efficiency
How Do Heat Pumps Work?
Heat pumps run on electricity, although they require less energy to operate than electric pool heaters. According to the Department of Energy, While heat pumps are acknowledged to be more environmentally friendly and energy-efficient, they also provide a less instantaneous service. In other words, it takes time to heat your pool with a heat pump.
Heat pumps transfer heat from an existing source, such as air or water. They draw in outside air through a fan and channel it over an evaporator coil. The coil absorbs heat from the outside air into the liquid refrigerant, which becomes a warm gas.
This differs from pool heaters, which generate heat using fuel, electricity, or solar energy.
The gas is then directed through a compressor, which increases the temperature further before sending it on to the condenser. This process transfers heat from the hot gas in the coil system into the pool water.
The hot gas is then recycled back into the evaporator, to be reheated as more air and pool water are drawn in. Despite providing less instantaneous results, heat pumps are rapidly growing in public popularity, according to Poolman.
Geothermal Heat Pumps
Geothermal pool heaters source their energy directly from the earth. This allows geothermal devices to access a consistent and renewable energy source. Geothermal heat pumps are highly energy-efficient, even more so than air-source heat pumps.
Geothermal heating typically requires an underground system of pipes or an earth/water loop. One geothermal pump and HVAC system, according to A&C Trades, can serve as a water heater for both the pool and residence.
Another advantage of geothermal heat pumps is that they are not reliant on the outside temperature. Due to the constant nature of geothermal activity, the source of energy can be utilized regardless of weather conditions.
Pros and Cons of Heat Pumps
Heat pumps, either air-sourced or geothermally water-sourced, are gradually gaining favor for pool water climate control. When choosing what type of unit to heat your pool water, it’s important to weigh the benefits and drawbacks carefully.
Pros
- Low operation cost
- Unit longevity
- More environmentally conscious (zero pollution emissions)
Cons
- Higher purchase price
- Relatively slow water heating rate
- Air-sourced heat pumps require an outside temperature of at least 45°F (7.22°)
Average Monthly Cost of Pool Heaters vs Heat Pumps
Heat pumps are more energy-efficient, making them cheaper to run. The spontaneous heating ability of gas-powered heating pumps comes at a higher price. Any pool owner knows that maintaining a pool adds up to the monthly budget.
Here is a chart comparing the monthly cost of running various types of pool heaters, according to data sourced from Home Advisor:
| Type of Pool Heating Unit | Monthly Operation Cost |
| Air-sourced heat pump | $120-$200/month |
| Electric resistance heater | $175-$600/month |
| Natural gas heater | $200-$400/month |
| Propane heater | $200-$850/month |
What Is the Difference Between Electric Heat Pumps and Electric Resistance Pool Heaters?
The difference between electric heat pumps and electric resistance pool heaters lies in the heating method. Electric heat pumps absorb heat from the air outside, while electric resistance heat pumps generate heat internally.
The use of electricity in the heat pump is only to power the mechanism, not to generate heat.
This differs from the pool heaters, which employ a metal resistance rod to generate an electric current, powering the heating unit.
In terms of unit performance, the major difference between electric heat pumps and electric resistance pool heaters is the energy efficiency and operating cost.
Electric heat pumps, which source heat either from the air or geothermal water, are far more energy-efficient and sustainable than resistance pool heaters.
Final Thoughts
The ability to heat pool water is an important feature to pool owners. For this reason, it’s important to carefully consider the type of heating unit employed in your pool.
The difference between the two major types of pool heating units–heat pumps and pool heaters—is that the heat pumps absorb outside heat, making them more sustainable but less on demand. Pool heaters, alternatively, generate heat internally, either in a combustion chamber, heating element, or electric resistance current.
This makes them generally more expensive to operate and less environmentally friendly than heat pumps, although this method allows for rapid temperature change.