Recently I found that when I turned on the electric for my hot water heater in my 2006 Itasca Sunova Class A 26P, the pressure relief valve was leaking, dripping. I found that basically this is normal when the water first heats up. Over time it will stop. It’s the water expanding and the pressure properly being handled by the valve. So simply check back in an hour or so and if it has stopped, no problem.
This should stop however, after it has stabilized. If not its a good idea to carefully, snap the metal lever to let some pressure out and possibly dislodge any debris that might have caused this to continue beyond normal operating procedure.
If it continues to leak then its an easy replacement and not costly. The valve is under $15 at a Lowes, HomeDepot or any hardware store. Be sure you match the pressure relief and BTU rating of old valve and MAKE SURE that the new one has the same length of thermal element that fits into the tank if it is a top mounted valve. Of course, turn off all power to the heater, close rig water inlet valve, allow the tank to cool down and drain before removing the old valve.