How do I drain my water heater? Does the low end drain being opened drain the water heater too or is there something else I need to do to drain it to winterize it
Depending on the make of water heater, to drain the water heater tank you must remove the "drain plug" or the "drain plug with anode rod attached" which is accessed by opening, or removing, the water heater cover on the outside of the RV.
You should have an Atwood water heater. There's a plastic plug near the bottom of the heater that has to be removed to drain the heater. The original ones had a 7/8" hex head. The new replacements have a 15/16" hex head.
A note of caution: If the plug needs to be replaced (they do wear out) be sure to replace it with the same plastic plug. They're available at almost any RV dealer and sometimes even Wal-Mart.
The Atwood water heater tank is aluminum, not steel like the Dometic brand. If you use a brass or steel plug it can have a galvanic reaction with the tank and corrode into place.