I have an Outback travel trailer by Keystone (model 21RS). I'm trying to winterize it and the manual says to turn the water heater by-pass valve to the by-pass position, located near the water heater incoming lines. I don't know where the incoming lines are, though I have located the access panel where the water heater is located -- but I don't see anything resembling a valve to turn or shut off. Does anyone know where this by-pass valve is? I tried calling someone at Outback and they claimed it was under the kitchen sink. However, I saw no such valve there either. Thanks for any help or suggestions.