There should be a switch on the control panel, likely near the door for operation on either electric or LP
(unless of course it's not duel function)
If it doesn't seem right....
like not hot water
or a little shot of hot then cold.....
then your bypass valving might not be set right
(you'll see some valves and some tubing..... water in the heater, water out of the heater, and a short tube with a vlave in the middle that connects the inlet and outlet. The connection should be closed, the others open)
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