What good is a pool if it is too cold to swim in? And there's no sense in having a spa if the water can't be raised to a therapeutic level that reduces the day's stress and eases muscle tension.
A heater is essential if you have a spa and can be necessary if you live in a cool climate where pool water may need an occasional boost. A heater, in combination with other devices such as a pool cover, can extend the swim season by several weeks or even months.
Pool heater maintenance varies depending upon the type of system that you have. A gas heater contains burners that should be vacuumed at least once each year to remove spider webs and other debris that can clog the burner ports. After you vacuum the burners, you should check for gas leaks at all connections.
To check for gas leaks, make a solution of liquid dish soap and water in a spray bottle (one tablespoon in a cup of warm water). Spray the soapy solution onto the pipe joints and look for little bubbles to become big ones. If you see big bubbles, turn off the gas and call your local utility company or a qualified plumbing contractor. Do not use the heater until the gas leak has been repaired.
Electric heaters contain heating elements (such as those on your stovetop) that can become covered with scale (mineral deposits). Often, scale can be stripped from an element by removing it and cleaning it using a wire brush. Some elements are so far gone that replacement is the only alternative. Bring the old element to your pool and spa supply store for an identical match.
To change an electric element, first turn off the power to the heater to avoid injury. Next, open a drain plug to remove excess water, remove the old element, and install the replacement. Make sure that the system is full of water and the pump is operating before powering up the heater to avoid damaging the new element.
When purchasing a replacement element, buy an extra to have on hand should one go out when you least expect it -- such as during a backyard party. The water won't have a chance to cool off, and you'll be a real hero.