Pool Heat Pumps
Pool Heat Pumps
A pool heat pump borrows the familiar technology used in home heat pump systems, which compresses a refrigerant to generate heat. When condensing fluids like refrigerants are compressed, they turn into a super-heated gas, which is then pumped into a condenser or heat exchanger, where it transfers the heat to the pool water. The gas returns to a liquid as it cools and is pumped back into the condenser, where the cycle begins again.
Pool heat pumps extract heat from the outside air by drawing air over the evaporator coil, which is absorbed by the refrigerant. The outside air temperature should be at least 50° for a heat pump pool heater to operate effectively and efficiently. They are most efficient in the 70-80° range, and when located in a sunny spot without excess wind.
Costs to Operate Pool Heat Pumps
Heat pumps are electrical, but they use very little electricity, enough to power the fan and compressor and control circuit. As the outside air temp becomes warmer, a pool heat pump runs less, and becomes more efficient.
There are several factors that affect the cost of heat pump operation. Using a pool cover, either an automatic cover or some type of solar blanket can reduce pool heating costs by 75%, no matter what type of pool heater you have. The temperature that you keep the pool is another huge factor affecting pool heating cost. Each 1° rise in temperature can require a 10% increase in pool heat pump operation time.
Nonetheless, pool heat pumps are over 5x more efficient to operate than a gas pool heater. That is to say, heat pumps can return 5 units of heat for every 1 unit consumed, whereas gas pool heaters are less than 1:1. But that does not mean that gas heaters cost 5x more to operate than heat pumps. In the real world, gas heaters cost about 2-3x as much to operate as an electric pool heat pump.
Your mileage may vary, but here’s a chart of estimated electrical costs to operate a heat pump pool heater.
Pool Heat Pump Installation
Placement: Installing a heat pump involves placing the heavy (300-400 lbs) unit onto a solid base of concrete or onto a sturdy AC unit base laid level over gravel. Ideally, choose a sunny location with low wind, and no overhanging eaves or trees. There should be clear space of 24” on three sides, for service access and for unrestricted air flow. Pool heat pumps are installed outdoors, with clear space above to prevent recycling of discharge air.
Plumbing: Once the unit is placed, it can be plumbed, or connected into the circulation system. This is accomplish by cutting the return pipe after the pool filter, but before any installed chlorinator. Connect the heat pump into the pool plumbing by gluing PVC pipe into the In and Out unions located on the unit. For high flow systems, check the flow rate maximum for your pool heat pump, and install an external bypass if necessary, to reduce the water flow in and out of the heater.
Power: Pool heat pumps use very little wattage, but they require a large amperage circuit breaker of 30-60 amps, depending on the size of the heat pump. An electrician is recommended for most pool heat pump installations, to properly connect power and to ground and bond the unit according to local codes. For many inground pools with a 100 amp service, there is sufficient amperage available to add a breaker to the sub-panel circuit breaker box at the pool equipment pad. In other cases, additional power may have to be brought to the equipment pad from the main panel circuit breaker box.
Pool Heat Pump Maintenance
One of the best things about a pool heat pump is how little maintenance is required. No sticky gas valves or rusty pilots, or any of the other frequent gas pool heater repairs. Pool heat pumps can last 10 years without a single problem, and many pool heat pumps remain in service for 20 years with only minor service. HVAC technicians, familiar with working on home air conditioners, will feel right at home working on a pool heat pump, since they use the same principles as heat pump air conditioners, only they operate in reverse, heating the refrigerant, rather than cooling the liquid.
Pool Heat Pump Sizing
Pool heat pumps range in size from 50K BTU’s to over 150K BTU’s – the size that will work best for you depends on the size of your pool, whether or not you cover the pool, how windy the pool area is, and how hot you want to keep the pool water. Generally speaking, 50-100K heaters are best on aboveground pools or very small inground pools. Medium to large inground pools should look at units that have 100-150 BTU’s of output. The larger the unit, the faster it will heat, and the greater temperature rise it can achieve.
Pool Heat Pump Features
There are some specific features offered on the more expensive pool heat pumps, which improve efficiency, convenience or durability. Some pool heat pump features include:
- Key-Pad Lock-Out for controls
- Self-Diagnostics and error codes
- Scroll compressor
- Titanium heat exchangers
- Automatic defrost of coil