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Solar Heat vs Gas Heat For Your Pool

A swimming pool is a wonderful addition to your home which will create memories and fun year after year. Yet when thinking about the purchase or ownership of a swimming pool often the most important consideration is omitted…. The addition of a pool heater.
Some think the initial cost is too much, while others think the monthly costs are too much, but lets take a closer look to see if that is really true.
First, with the average price of a simple backyard pool starting at around $40,000.00 in most areas of the country (2010 prices), the cost of a well designed heating system is just a little more than 10% of the pools initial price. Without a heater the “swim season”, (time of the year when the water is warm enough to go swimming), is about 4 – 5 months. 
If cost divided by usage is considered, then the purchase is made for a 4-5 month period of time. Now we understand there are many more reasons why the pool is a benefit year round, such as a beautiful place to entertain, and how it can be a practical extension of your home, but based only on the financial calculations it would seem the addition of a pool heater would be one smart move.
Think about it, for a 10% to 20% increase in the initial cost you can more than double the usable value of the pool easily achieving an 8 month to year round swim season. So since the economics are sound, lets take a look at some of the options.
There are several ways to heat a pool, but the three most popular are heat by natural gas, heat pump, or solar. While many believe a hybrid system consisting of both gas and solar is the best, we will save that discussion for another time and consider which of the three provides the best initial option.
For initial lowest cost, good reliability, year round capability, and the fastest capacity to heat the pool, natural gas is a clear winner. It will beat our both solar and the heat pump for speed of heating and how high it will take the water temperature. That said, t is also the most expensive to operate as you have the cost of “gas” added to the equation. This addition can be a big one adding several hundred dollars a month or more to the operating cost. While this may be feasible for an “occasional” heating, it is definitely cost prohibitive for longer heating cycles.
The “heat pump” is the next consideration. Though the heat pump is roughly twice the cost of a gas heater initially, it can easily save over 40% in the monthly operating costs due to system efficiencies. If you are considering long swim seasons for your pool, the heat pump should be a serious consideration.
The potential down sides of the heat pump are the time it takes to initially heat the pool, (no big deal really), and the fact that in most locations it will prolong, maybe even double the swim season, but rarely provide a “year round” swimming opportunity. The more specific answer to this is the outdoor temperatures. While a heat pump can operate all the way down to 40 degrees of outside temperatures, it looses efficiency at any temperature below 50 degrees. Still it will definitely prolong your season and will be less cost if amortized over a 1 to 2 year period including operating costs.
Lastly lets consider “solar” pool heating. Solar will have the highest initial cost, but this in itself can be deceiving. In most solar installations there are federal and possibly even state tax credits that apply to your system costs. These credits can be significant and once applied will reduce the initial cost below the cost of a heat pump in some situations.
Then there is the HUGE benefit, and that is “free” energy from the sun, available every day the sun shines. When properly sized, (we recommend pool surface area x .8 = solar area min.), you can get up to 8 or 9 month swim seasons with no energy cost at all. Once you factor the energy savings into the equation combined with the tax credits, the system will almost always pay for itself in less than 2 years, most certainly less than 5.
Of course there is the same downsides with solar as there are with heat pumps and that is they are highly effective in about the same temperature ranges. Once the average temperature drops below 50 degrees efficiency drops off as well. Below 40degrees they are not working very effectively at all.
One largely overlooked benefit of the solar is their ability to also “cool” the pool. While this might not be a requirement in some parts of the country, in desert climates like out in Arizona, Nevada, and parts of Southern California, pools can actually get to be too hot. In this case the solar can be run at night instead of in the day. While running at night the heat from the pool is passed through the “radiator” of the solar collectors where the heat radiates back into the black nighttime sky.
Once considered, these factors will help you make the right choice for you. The best thing to understand is this… no matter what you decide, adding a heater to your pool is a huge benefit in that it enables you to double the use of your pool, and that sounds like a great idea… doesn’t it!
Author, Rex Richard, is a world famous pool and solar contractor who now provides education programs to the pool and spa industries