The most common problems with a swimming pool heater include failing to turn on, turning off before the water reaches the desired temperature, and making loud noises when turned on. Some common problems are caused by a dirty filter or debris inside the machine.
Swimming pool heaters that do not turn on may have corroded electrical terminals, a malfunctioning safety switch, or a malfunctioning high limit switch. Electrical components, such as the safety switch, are tested with a voltage meter to determine whether the component is operating properly.
If the swimming pool heater turns on but doesn't heat the pool adequately, check the timer to ensure it is set properly. Other problems that can cause the swimming pool heater to heat inadequately include a dirty filter, debris inside the valves and a malfunctioning thermostat. Swimming pool heaters that are too small for the pool also fail to heat the water and should be replaced with a properly sized heater to correct the problem.
When debris enters the heater's hoses or filter, the heater can make loud noises while in use. A faulty pressure switch can also cause loud operation. To remedy this problem, back-flush the filter to remove the debris, or contact a professional repair company for assistance.