AO Smith ProMax Water Heater Troubleshooting

If you own an AOSmith ProMax GPST-40L Water Heater and are having problems with the way it is performing I’m sure the last thing you want to do is spend your hard earned money hiring a technician to repair it. Thanks to this constantly evolving, technology oriented world you have access to this very handy troubleshooting and repair guide. This guide covers many possible problems that could occur, such as: Temperature problems, noises, odors, leaks etc. If for any reason you feel as though you cannot safely perform these (or any other) repairs, please contact a professional technician.

PROBLEM: Water leaks.

SOLUTION: One of the causes of leaks in hot water heaters is when the hot or cold water valves, thermostat threads or other fixtures are not connected or sealed properly. You should always make sure that any threaded connections are secured and functional. Sometimes there might be leaks from other surrounding appliances or water paths so check to see if that is the case. One other cause could be condensation of the flue products, in order to correct this you should use some sort of cloth material to absorb the condensation coming from the exhaust vent (near the blower assembly).

PROBLEM: Water odors.

SOLUTION: Most of the time any odors in the water are due to high sulfate or mineral deposits in the water or increased bacteria counts. Too solve this problem it is recommended that you completely drain and flush the hot water heater and then refill it. Don’t forget to chlorinate the water as well.

PROBLEM: Vent pipe too hot.

SOLUTION: Commonly this is caused because the dilution air is too hot to mix with the flue gases or because there is not enough of it to mix with the flue gases. You should make sure that there are no obstructions internally or surrounding the air intake at the draft hood.

PROBLEM: Yellow flame

SOLUTION: The correct color of a flame for a water heater should be blue-ish, if your flame is yellow you should try cleaning the burner heads or ensure that there are no blockages in the air intake or exhaust venting in the bottom base pan.

PROBLEM: Not enough hot water

SOLUTION: First make sure the unit is plugged in and that the switch is turned to the “ON” position. If you can’t turn the unit on, make sure the electrical outlet you are using is working properly. Sometimes when the water is not heating up it could be a problem with the thermostat, in which case you will need to either check that it is wired correctly or replace the thermostat. Before you go to that extreme though, check that the temperature control knob is at the appropriate level. Another possibility is that the control harness or the blower motor might need to be replaced. Check to see if there are any leaks in the hot water connections as well as the external fixtures. Also be sure that the gas pressure is at the correct level, if it is too low it can cause the water to become cold too quickly.

PROBLEM: Reverberation or sizzling noises.

SOLUTION: Generally the reverberating type noise could possibly be caused by excess dirt at the bottom of the water heater tank. If this is the case you should try completely draining and flushing the unit and refilling it with chlorinated water. If you hear a sizzling noise it could be because of condensation dripping on the burner heads. Refer to the section on “water leaks” for instructions on how to fix the condensation.