By Chris Normandeau
Director, FS Energy
With so much sunshine and beautiful pools everywhere, spending an afternoon at the pool comes second only to spending it at the beach. Even in the sunny warmth of Florida, water in a swimming pool
isn’t usually warm enough naturally for a lot of people to enjoy it. Solution? A pool heater. What kind of heater do you need? There are several options for your pool temperature needs, and each has its pros and cons, according to Chris Normandeau, director of FS Energy.
Common types of pool heaters include natural gas or propanefired hot water heaters, electrical resistance heaters, heat pumps that use a water or air source and solar thermal heaters.
Most of the heat that is lost from a pool, even one that sits in the Florida sun all day, is lost due to evaporation – more than 70%. “Evaporation cools a pool in the same way that a fan cools you down when you’re sweating,” Normandeau said. “As the water evaporates, heat leaves with it. Heaters have to counteract that evaporation to be effective.”
The heat loss through evaporation is faster in pools with more surface area and in pools located in windy areas such as rooftops or on the coast.
In addition to different types of heaters, there are different types of fuels for them. In terms of cost, natural gas is the least expensive, followed by electricity and propane, which are both more expensive. The expense of the fuel
is only one factor in the cost of running a pool heater; the type of heater combined with the fuel will provide your overall cost.
As mentioned above, there are a few common types of heaters to maintain your pool temperature. What are the pros and cons of each?
Gas-Fired Water Heaters
As the name implies, a gas-fired water heater burns natural gas and the flame heats the water. They are relatively simple to operate, are the most common type of pool heater and offer fastest heating time, which is important if it’s chilly out. On the flip side, they are costly to run, because although natural gas may be less expensive than electricity, they are not as efficient as other technologies when it’s warm out. If natural gas isn’t available in your area, running them on propane becomes very costly.
Electric Resistance Heating
Electric resistance heaters are the most costly option for heating a pool. They use electric currents to generate heat and are mostly used for spas and small pools. “I can’t think of an upside to using an electric resistance pool heater,” said Normandeau. “If a property is using that kind of heater, we’re happy to talk to them about more efficient options.”
“Think of a heat pump like a reverse refrigerator,” Normandeau said. “They take heat from one space and move it to another. In a refrigerator, they take the heat from the inside, and move it to the outside. With a pool, they take heat from a source and move it to the water.”
Heat pumps are inexpensive to run, but typically act more slowly to heat water than a gas-fired water heater will. There are two types of heat pumps: air source and water source. An air source heat pump (ASHP) pulls heat from the air and uses that to warm up water in the pool; however, if there’s no heat in the air, an ASHP will not work effectively because there is no heat to move.
A water source heat pump (WSHP) can be more effective than an air source one, assuming the water is the right temperature. The water typically comes from a well or a lake, or from the condenser water loop in a high-rise building. Installing a WSHP will be the more expensive of the two options if a well has to be drilled. The equipment is more expensive up front, but it can be less expensive to run over time, will have a longer life, and isn’t as vulnerable to cold temperatures. An ASHP, while less expensive initially, also comes with fans and compressors that can be noisy and has the shorter life of the two systems.
Solar thermal heaters draw heat from the sun, use it to heat storage material and heat the water from there. Although solar thermal technology is very trendy, it’s less common than any of the other types of heaters. It can be the cheapest to run because there are no fuel costs, but the system is both more complex than others and the most expensive initial investment. Solar thermal heat is obviously dependent on weather conditions, so sometimes a backup gas or electrical heater is needed as well, which is, of course, an additional expense.
When choosing the right pool heater for your property, keep the following in mind: gas-fired heating is best for pools that are on the beach or windy areas and outdoor pools in colder regions. Heat pumps or solar can be considered for other pools. Always consider overall typical climate conditions, as well as both investment and operating costs.