Glassbird -- you got lots of good suggestions; however, no one showed you a diagram of what you are conceptually trying to do, & what exactly are you bypassing. Here is a conceptual drawing that shows you what you are trying to accomplish.
The whole concept is to By-pass the water heater so that when you winterize you aren't pumping 6 gallons of RV antifreeze into the water heater tank. So you have a cold water line going into one end of the water heater tank and you have a hot water line coming out of the water heater tank. So to complete a by-pass installation you need to install a valve in the cold water line going into the tank to close off that potential flow. Then you need to install a valve in the hot water line to close off that potential. When those two valves are open your water heating system is operating normally. When you close both those valves your water heater tank is now isolated -- no potential flow into it, no potential flow out.
Now comes the By pass piece. Close to those two valves on the intake and output of the water heater you are going to have to install a line that connects the cold water input to the hot water output. In the middle of that by-pass line you need another valve.
So with the cold water input and hot water output valves closed, you would open the valve in the bypass line you just installed. You can see that any cold water flow going to the water heater is stopped and that cold water flows directly into the hot water output. When you are winterizing, the antifreeze you syphon into the cold water line now bypasses the hot water tank and only flows into and through pex tubing. None gets into the hot water heater.
Part of winterizing is to take the plug out of the hot water heater tank so that the 6 gallons of water drains out.
Normal Operation -- Cold Water Input Valve to heater OPEN Hot Water Output Valve OPEN Water Heater Bypass valve CLOSED
Winterizing Operation -- Cold Water Input Valve CLOSED Hot Water Output Valve CLOSED Water Heater Bypass Valve OPEN
You can see this clearly in the two schematics I attached.
Ed & Bev Felker
Retired USAF Col and retired Nurse
Traveling with Lily & Bella ('Teddy Bear' breed)
2015 Vegas 24.1 (E-350)