garyemunson wrote:
I see the OP is from California...a state where many people have no need to winterize. If you don't drain the water heater down on occasion (taken care of by winterizing) like Chris said above, over time the air cushion in the top pocket of the WH gets absorbed by the water and will cause that issue when the water heats and expands with no place to go except by pushing out through a fitting. "Time2roll" mentioned an expansion tank..not really needed with an RV water heater because of the built in air pocket. Exactly why it is there.
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An expansion tank will, however, keep the pump from running every time a tap is opened.