Originally Posted by klpoppe
Mine empties when I open the low point drain valves to drain the water lines. Make sure you open all of the faucets when doing this. Also open the pressure relief valve to prevent a vacuum in the tank which will keep it from draining.
Once you open all the faucets (hot and cold) and turn off the pump, the water heater will drain.
However, the plug, I believe is lower in the tank than the cold water inlet.
Any particular reason for draining the system between trips? Because once you open the water system to atmosphere, you will HAVE to re-sanitize and refill for every trip.