A guide to the different types of pool heaters:

Gas and propane pool heaters

• Most common and work most rapidly.
• Natural gas if you have it, or propane tanks mounted above or below ground.

Gas heaters

Now boast of up to 90% efficiency ratings, and consume only as much gas as you allow. A gas pool heater is thermostat controlled, so you can set it and forget it. It will also have an on/off switch, pressure switch, gas valve and high limit switches in its safety circuitry. Heaters must be installed and vented properly or hazards could result.

Heat pumps and solar heaters are cheaper to maintain and are gaining in popularity. About 20% of pool heaters installed are now solar.

Heat Pump

Extracts "free heat" from the surrounding air. This is accomplished through a refrigerant vapor compression cycle that transfers heat from one source to another. It can be compared to a household air conditioning system "in reverse". Heat pumps are a clean, economical way the captures "free heat" from the ambient air. A heat pump draws the natural warmth from the air and uses it to maintain a comfortable temperature. Heat pumps are commonly used from Florida to Canada and very efficient down to 50 degrees Fahrenheit to allow your swimming pool to remain operational when night-time temperatures approach this range.

Millions worldwide have been enjoying solar heated swimming pools for over two decades. You will probably find that you will pay much less for a solar heater for your above ground or small in ground pool than for any other type of heater. While the first solar systems for larger in ground pools may equal or somewhat exceed those of other heaters, they return the cost difference in fuel savings in the first year or two.

Solar Pool Heating System

Uses your existing pool pump to circulate water through the many small passages of the solar collector, where it is warmed by the sun. This heated water then flows directly back to your pool through your regular pool plumbing. This simple cycle continues until your pool reaches your desired temperature. You can cool an overheated swimming pool in warmer months by simply running the pool pump at night.

Solar Cover or Blanket

Made from thin plastic formed with air pockets so it can float on the surface. A solar cover cannot heat a pool. It is not totally transparent to sunlight so it blocks out much of the sun's energy that would otherwise heat the pool. However, it prevents evaporation from the water surface, slowing down cooling of the water at night and in bad weather. Use of a pool cover is recommended at night on above ground pools with a solar heater. A solar cover or blanket will help a pool retain heat, but a solar system actually adds heat to raise the temperature of your pool water. If you have a larger solar heater on an in ground pool you can use a cover at night near the beginning and end of the season when the nights are long and cool.

-- Tips courtesy of HomeAdvisor.com