Any damage to Water heater in the attic, if main water to the house is shut off for a month when owner on vacation, please? Thank you in advance for your help.
There should be no damage, but of course this would be non-freezing conditions. What setting would you leave the heater on? If electric, I would say switch off power to the heater. If gas, switch to vacation/pilot setting or even turn gas off at the heater.
Upon return I would turn the heater to hot (140 F) and let it come to temperature, then run hot through all delivery points.