[rheavn]

Here are a a couple tips I got from Newell service if any one is changing out the AquaHot temperature gauge sensor.

You can't use sealer on the sensor threads as the sensor gets its ground through the threads.

Also prior to removing the old sensor: let the unit cool to room temperature. Take the radiator cap off to relieve any pressure. Put the radiator cap back on--this causes a suction. Now remove & quickly reinstall the new sensor. They said using this procedure will allow very little coolant to leak out and only a couple paper towels under will absorb it.