A heat pump efficiently transfers heat from one location to another using minimal energy. For pool heating, it draws warmth from the outdoor air and transfers it into the water. Unlike gas heaters that rely on natural gas or propane, heat pumps utilize existing heat and run on electricity, offering a cleaner, eco-friendly solution with no carbon monoxide emissions.
Why Choose a Heat Pump for Water Heating?
1. Year-Round Pool Use
Swimming pool heat pump are ideal for warmer climates, performing most efficiently when outdoor air temperatures are above 50°F. As temperatures rise, their efficiency improves, making them perfect for consistent heating.
2. Energy Savings
Heat pumps offer significant energy savings compared to gas heaters. While gas heaters heat pools quickly, they consume far more energy. Heat pumps, though slower, maintain even and consistent heating at a much lower cost.
3. Dual Functionality
Some premium heat pumps can both heat and cool your pool. They provide a comfortable swimming experience year-round, whether you need to warm the water or cool it down during hot weather.
How a Heat Pump Pool Heater Works
As pool water circulates through the pump, it flows through a filter and then the heat pump heater. A fan in the heat pump draws in outside air and directs it over the evaporator coil. The liquid refrigerant in the coil absorbs heat from the air, turning into gas. This gas passes through the compressor, which increases its heat, creating hot gas that moves through the condenser. The condenser transfers heat from the gas to the cooler pool water. The heated water returns to the pool, while the gas cools and condenses back to liquid, repeating the cycle.
High-efficiency heat pump pool heaters often use scroll compressors instead of standard reciprocal compressors.
These heaters perform efficiently when outside temperatures stay above 45ºF–50ºF. As outside air cools, efficiency decreases, raising energy costs. However, this is typically not a concern since outdoor pools are mainly used in warm weather.
Selecting a Heat Pump Pool Heater
Heat pump pool heaters cost more than gas pool heaters, but they typically have much lower annual operating costs because of their higher efficiencies. With proper maintenance, heat pump pool heaters typically last longer than gas pool heaters. Therefore, you'll save more money in the long run.
When selecting a heat pump pool heater, you should consider its:
- Size.
- Efficiency.
- Costs.
Sizing a Heat Pump Pool Heater
A trained pool professional should perform a sizing analysis to determine the appropriate heater size for your pool.
Heat pump pool heater sizing depends on factors like the pool's surface area and the temperature difference between the pool and average air temperatures. Other considerations include wind exposure, humidity levels, and cool night temperatures. Pools in areas with higher wind speeds, lower humidity, or cooler nights require larger heaters.
Heat pump pool heaters are rated by Btu output and horsepower (hp), with standard sizes such as 3.5 hp/75,000 Btu, 5 hp/100,000 Btu, and 6 hp/125,000 Btu.
To approximate heater size for an outdoor pool:
1. Determine your desired pool temperature.
2. Identify the average temperature for the coldest month of use.
3. Subtract the average coldest month temperature from your desired temperature to find the required temperature rise.
4. Calculate the pool’s surface area in square feet.
5. Use the formula:
Pool Area × Temperature Rise × 12
This calculates the Btu/hour output, assuming a 1º–1.25ºF rise per hour and a 3.5 mph average wind. For a 1.5ºF rise, multiply by 1.5; for a 2ºF rise, multiply by 2.0.
Determining Heat Pump Pool Heater Efficiency
The efficiency of water heat pump for pools is measured by the coefficient of performance (COP). A higher COP indicates greater efficiency. The federal test procedure for these heaters uses conditions of 80ºF ambient dry bulb temperature, 63% relative humidity, and 80ºF pool water. COP values typically range from 3.0 to 7.0, equating to an efficiency of 300%–700%. This means that for every unit of electricity used to operate the compressor, the heat pump produces 3–7 units of heat.
Installation and Maintenance
Proper installation and maintenance ensure optimal efficiency for heat pump pool heaters. A qualified pool professional should handle the installation, particularly the electrical hookup, and perform complex maintenance or repairs.
Refer to the owner's manual for maintenance schedules and recommendations. Annual tune-ups are typically necessary. Given the numerous moving and electrical components, periodic servicing by an air conditioning technician is often required.
With proper care, heat pump pool heaters can last 10 years or more.
