Pool heaters typically require the least maintenance of all pool equipment. Gas heaters can work fine without being serviced for a couple years, and electric ones can last even longer. Consult your manufacturer's manual for specific care instructions. Sometimes, calcium scales build up inside the tubes of a heater and restrict flow, preventing the water from heating adequately. If this happens, recruit the help of a professional because the heater may need to be disassembled and have its tubes cleaned out with a wire brush or acid. Hiring someone to service your pool can cost $100 or more per month, depending on the maintenance your pool requires.