The implementation of these cost effective systems enhances the enjoyment of a swimming pool and adds value to the home. A cold swimming pool is unused, and offers no return on investment. 

Proper sizing and installation, in addition to a quality product are primary concerns when considering using this form of solar energy.

Reprint of pool heating article.

David Boehmer is a State Certified Solar Water Heating Contractor working with Florida Solar Energy Systems in Sanford, the area's leader in terms of number of heated pool systems installed. Here, in an article prepared for House & Home, he discusses the choices and opportunities to increase the water temperature of your pool during these cooler months ahead, and explores the merits of gas, electricity, heat pumps and solar systems.

By David R. Boehmer

You've finally built that swimming pool you' ve always wanted and – unless you happen to be in the four month summers season between late May and mid-September – there it sits.

Although Central Florida has warm and sunny days almost all year, cool nights during the springs and fall months generally drive the temperature of an un- heated screened swimming pool down to 65-70 degrees Fahrenheit, which is too cold for most folks. Screened pools drop to the low sixties during the winter months, so low that your pool doesn't have enough time to get back even to the mid-seventies during the beautiful Florida days we often enjoy in between winter cold fronts. And many dual income couples who have to swim during the evening can't even use their pool comfortably during the summer. Sound familiar?

OK. You've decided you need a swimming pool heating system. Before getting into equipment and c, your first step is to examine you pool use. Why did you buy your pool'! Backyard recreation for the kids'! Do you need to swim for a therapeutic purpose? (If so, the cost of a heating system can be a tax deductible medical expense.) Are you and your spouse only able to use the pool during the evening because of dual careers? And a realistic question: If you use your pool only occasionally now even during warm weather, would you really use it more if it were heated?

How many months are you able to swim comfortably now, and how many more would you like to add to your swim season? Who uses the pool most'! We all know that children are less sensitive to cold water than adults, and women generally prefer warmer temperatures than men.

There are four major ways to raise the temperature of your pool: pool covers, natural or propane gas heating, electric heat pump and solar heating. Each has strengths and drawbacks and the best choice for you depends on your unique needs.

POOL COVERS

Most swimming pool heat loss occurs at the surface. The least expensive way to maintain a warmer pool is by keeping a cover on the pool during the nighttime hours, when surface evaporation would otherwise cool the pool down. The cover stops this nighttime evaporative would otherwise cool the pool down. The cover stops this nighttime evaporative heat loss and enables the pool to stay at a higher temperature. Pool covers are not difficult to use and can easily add two months to your comfortable swim season.

Pool covers cost between $85 and $150 for most residential pools. In fact, all of the other pool heating methods discussed in this article should only he used in conjunction with a pool cover. Not to do so would be like running your house air conditioner during August with the doors and windows open. The system will still work, but the operating cost will be as much as three times higher.

GAS HEATING

The advantages of gas are low initial cost ($800 to $1500) installed including a propane storage tank, for a typical residential pool the ability to maintain a desired temperature during almost any weather conditions, and very fast recovery (the period of time needed to bring the pool up to temperature.) The principal drawback is operating cost. For a typical heating season propane costs to maintain a 15X30 Central Florida screened pool at 80 degrees Fahrenheit are about$1,200 when a pool cover is used and can exceed $3,000 with no pool cover in use. While many pool owners now consider gas prohibitively expensive, you may want to consider it as a winter supplement to another, more cost effective form of heating if you need to swim for medical reasons.

ELECTRIC HEAT PUMP

Electric swimming pool heat pumps take heat out of the outside air and put it into the pool, generally producing three to five units of usable heat energy for every unit of electricity consumed. As a result, heat pump operating costs are about half of that for a gas heating system – about $540 with a pool cover for the same pool scenario described in the gas heating example and about $1,800 with no pool cover in use.

While a better deal than gas, these operating costs may not be acceptable to budget -minded pool owners when combined with an initial investment of $2,500 to $5,500. And if you go the heat pump route, make sure you get a big enough unit at the lower end of the price range only to learn that it may not maintain a typical residential pool at 80 degrees during much of the winter heating season.

Why don't smaller heat pumps do well in extremely cold weather? Colder weather requires the machines to run longer – as much as 24 hours in the case of a 60-80,000 Btu/Hr. machine during a winter cold front. Although manufacturer hourly heat output ratings multiplied by the longer running hours might suggest that the smaller machine can do the job, a heat pump does not produce heat at anywhere near its rated efficiency when it is forced to run during much of the colder nighttime hours (below 50 degrees.) So if you have a pool surface area of 300 to 600 square feet and want year-round swimming at 80 degrees or better with a heat pump, install a 90,000-118,000 Btu/Hr. model.

SOLAR POOL HEATING SYSTEMS

In these systems, pool water circulates through a large heat exchange surface, usually located on your roof, and absorbs the sun's energy. The principle is similar to the way your car radiator works, only these solar heat exchangers collect heat instead of radiating it. Most solar "collectors" are flat black panels manufactured from high technology plastics which have been designed to resist weather and ultraviolet radiation.

The major advantage of these systems is that because sunshine is free, they have no operating cost. Another plus for environmentally concerned pool owners is that solar energy is renewable and non-polluting. The major disadvantage is that solar does not provide heat on demand. In other words, the solar system can only put into the pool the heat which is available from the sun on any given day. You cannot make more solar energy the way you might burn more gas or use more electricity to maintain your pool heating system used in conjunction with a pool cover can more than double your comfortable swim season, from four months to nine or ten months every year.

So why, you ask, doesn't every pool have a solar heating system? Solar pool heating systems do require an initial investment of $3,000 to $5,000 for a typical 300 to 400 square foot surface area residential al pool with no special installation requirements...but a properly sized system with a life span of 15-20 years can pay for itself with energy savings in 2-to-3 years.

While there are only small differences in the heating performance (Btu per square foot of solar panel) for most of the solar pool heating panels on the market today, a variety of factors can cause significant price variations. One is that solar systems which face south require fewer panels then systems which face east or west. Another factor is desired swimming season. When comfortable swimming is desired during the colder winter months, more panels must be added to the system in order to collect the additional heat needed each day to offset colder air temperatures and reduced solar energy available. Different mounting methods, warranties, esthetic touches, and electronic control systems are other options to be aware of.

Because solar heating technology can be confusing to the average pool owner, it is advisable to contact a state certified solar contractor when you look into solar heating.