Water Heater

[Doncamper]

Hi
WE have an 09 3400 Montana 5th wheel and really love it.
One problem...our water heater makes a loud humming noise when the hot water is turned on. It does it on the gas or electric setting.
Would appreciate any suggestions
Thank you

[Slufoot733]

Be sure the valves in the input and output lines are FULLY OPEN, and the by-pass valve is FULLY CLOSED. If a valve is partially open the water can make a loud noise while passing through the valve. That's all I can think of at the moment.

[carlson]

Suggestion,
Is the sound coming from under the kitchen counter.
IF so it is the water line check valve, if you look and you should see a copper piece of plumbing that the plastic hose attaches to in the hot water heater.
It is the check valve.
Yes sometimes the bypass valves are not all the way open, but most of the time it is check valve.
E. Sven

[Doncamper]

Thank you we will give both these a try