I have a State water heater with the power vent and for some reason the blower is running continuously. Is that normal condition and if it is not how to approach the problem?
Most of the time the problem with the blower is related to the air pressure switch or vent system.
First, check the wiring of the air pressure switch that is properly connected and is not damaged.
If the wiring is OK, make sure that the sensing tube that leads to the air pressure switch, is not kinked or damaged, and is correctly attached.
If the water heater is equipped with the Intelli-Vent control, you might have to replace it, if it does not energize the blower.
Use the multi-meter and when blower is running check the resistance in ohms on the air pressure switch contacts – the contacts should close and show continuity.
Further test should be taken to see is the element defective or not. The test involves measuring the air pressure at the sensing port on the blower. If the pressure is below the activation point of the switch you should check for the restrictions in the vent, too many bends, debris and dirt…. But if it is above the activation point than the air pressure switch has to be replaced.
The air pressure switch might open if the temperature limit switch is opened (defective). The switch opens its contacts when the temperature of flue gases rises and if the contacts are open at the room temperature, the switch has to be replaced.
Next is to check the vent system that is installed per codes and manufacturer instructions, has correct vent pipe size and the length and number of bends doesn't exceed maximum allowed.
Check for the blockage in the vent pipes and remove anything that prevent normal air flow and transfer of the exhaust gases.