Winterizing your cabin or RV is a tedious process. If you're not afraid of doing a little bit of plumbing, you can skip filling your water heater with antifreeze before the cold weather sets in. You don't have to remove your water heater; all you have to do is install a set of bypass valves.
Before You Start
Before heading to the home improvement center, check the size and type of pipes attached to your water heater. Make a list of the fittings and tools you will need to complete the job. Most water heater manufacturers specify that plastic fittings should not be used within 12 inches of the heating unit.
The basic plan for a bypass is to put a pipe between the hot and cold water pipes that are connected to the heater. This pipe allows water from the cold-water feed to be shunted directly to the hot-water pipe without entering the water heater. Two different types of valve setups are commonly used to direct the flow of water.
Three-way Valve Setup
Three-way valve bypass kits are commercially available for RV use. A three-way valve is installed on both the hot and cold water lines. When both valves are positioned to direct the flow of water through the bypass, the water is prevented from entering the heater from either line. Moving both valves to the normal operational mode directs water through the heater and completely stops flow through the bypass line.
If you can't find three-way valves, three regular on/off valves can perform the same function. Place one valve on the cold water line and one valve on the hot water line. Both valves should be placed between the heater and the bypass line. The third valve should be placed at the mid-point of the bypass line.
To bypass the heater, turn the valves on the hot and cold plumbing lines to the off position and open the valve on the bypass line. For normal operation, close the bypass valve and open the hot and cold valves.
Turn off the water heater before turning off the water supply. If you drain the heater's tank for the winter, turn on the water supply and run the plumbing long enough to remove all the air from the tank before restoring power or relighting the heater.