There are many reasons why a pool heater won't start. A common cause is a faulty pressure switch; this switch serves as a safety feature that's built into pool heating systems that start the heating process. You can also troubleshoot a pool heater that won't start by checking your water level and filtration system for blockages. It takes 15 minutes to troubleshoot a pool's heater.
- Check the skimmer baskets for obstructions and debris
Look for blockages in the pool's skimmer baskets. Free the stuck skimmer doors, and empty the strainer buckets.
- Add water to the pool
If a vortex can form in the skimmer basket, the pool's water level is too low. Fill the pool with enough water to keep system pressure stable, and stop fluctuations in water pressure that disengage the switch.
- Clean your filter
A dirty filter blocks flow, resulting in low water pressure. If the difference between the filter's intake and outlet pressure gauges is greater than 8.5, backwash or clean the filter according to the manufacturer's directions.
- Set the thermostat to a temperature higher than the current temperature of the pool
Pool water temperature fluctuates. Make sure that the thermostat is set to a temperature that is higher than the water in the pool.