[rohrmann]

I think the check valve on the back of the water heater that is there for winterizing is the cause of the cold burst when you turn the water back on in the shower. The spring loaded valve stops any hot water to flow when the button on the shower wand is closed. The extremely slow water flow isn’t enough to keep the check valve open, so the only water flowing is the cold, until you open the valve on the wand when hot water starts flowing again. If you never had to winterize, you could just remove the check valve and probably would never have a cold burst of water again.