Pool home with solar panels

Extend Swim Season with a Pool Heater

The worst of the summer heat may be past us here in Florida, but that doesn’t mean we’re ready to give up on swimming just yet.

Cost comparison for pool heatersKeeping your pool covered when not in use will help maintain water warmth, but many pool homeowners opt to extend the season further with a little help from a pool heater.

Common types of pool heaters include:
• Solar Heaters – Extend your swim season
• Heat Pumps – Swim year-round
• Gas Heaters – A good solution for spas

Solar heater
This product has the most cost-effective use of energy in many climates, particularly a sunny locale like Florida. Once the initial investment is made, there is little to no operating cost.  A solar heater is an effective way to extend your swim season a couple of months in the fall and in the spring, but will likely not result in year-round swimming.

Most solar pool heating systems include the following:

  • A solar collector/panels — the device(s) through which pool water is circulated to be heated by the sun
  • A flow control valve and thermostat — automatic or manual device that diverts pool water through the solar collector

Pool water is pumped through your pool’s filter and then through the solar collector(s), where it is heated before it is returned to the pool.

Sizing a solar swimming pool heating system involves many factors, including pool size, average regional temperatures, the site’s ability to collect sunlight, whether you use a pool cover, and more.

The basic measurement, however, is that the surface area of your solar collector should equal 50%–100% of the surface area of your pool. In cooler and cloudier areas, you may need to increase the ratio between the collector area and the pool surface area. Adding collector square footage also lengthens the swimming season.

For example, a 15-by-30-foot outdoor swimming pool in Florida typically requires a collector that equals 100% of the pool’s square footage to accommodate year-round use. This equals 450 square feet of collectors. In northern California, most people use outdoor pools 6–8 months per year, so they typically size their systems at 60%–70% of the pool’s surface area.

A solar system contractor can more accurately determine your particular system requirements, but you can get an idea using this calculator.

Heat pump
This product has higher operating costs than solar heating, but can extend your swim season even longer and potentially create year-round swimming.  A heat pump doesn’t actually generate heat – instead it uses electricity to capture heat and move it from one place to another. Homeowners often use a heat pump to supplement a solar heating system.

In this schematic from the Department of Energy, you can see how a heat pump works.

How a Heat Pump Works

The heat pump uses a fan to draw in outside air and directs it across an evaporator coil. Liquid refrigerant within the evaporator coil absorbs the heat from the air and creates a gas. The warm gas in the coil then passes through the compressor. The compressor increases the heat, creating a very hot gas that then passes through the condenser. The condenser transfers the heat from the hot gas to the cooler pool water circulating through the heater. The heated water then returns to the pool. The hot gas, as it flows through the condenser coil, returns to liquid form and back to the evaporator, where the whole process begins again.

A pool heat pump works well when the outside temperature in your area remains above 45ºF, as is typical of our area through the fall and even much of the winter; however, do keep in mind that the cooler the outside air they draw in, the more energy they use.

Use this helpful calculator to determine the approximate operating cost of a pool heat pump.

Gas heater
Gas heaterA gas heater costs significantly less than a heat pump and can heat water 5-7 times faster, but the operating costs are higher.    For these reasons, a gas heater is typically only used to heat spas or very small pools.

Use this helpful calculator  to determine the appropriate size gas heater for your particular pool or spa, and ask your pool professional for more information about different models and features.

When you add a heating solution to your pool system, your swim time can be as active as ever, even when the forecast calls for cooler weather!