Disconnect the power to the Hayward pool heater and allow the unit to cool completely.
Remove the water inlet connections and allow the water lines to drain.
Pull the heater forward slightly until all water has drained out of the unit.
Open the front access panel on the heater and examine the heat exchanger for soot using a flashlight if necessary. Contact Hayward for a replacement heat exchanger if there is soot or corrosion on the heat exchanger.
Allow the unit to dry completely and use a chemical testing strip on pool water to check for a chemical imbalance before restoring power.
Tighten any loose connections between the heat exchanger and the pressure switch and replace any damaged or broken gaskets.
Restore power to the pool heater.