I will try The valves and lines for the water heater ,that go into and out of, must be opened, and the line that is inbetween those two lines has a valve in it that you cant see on mine unless you l feel for it, for it is turned away from you. That vaLVE is opened in bypass mode and closed in regular mode (not bypass mode) My lines look like the capital letter (I). and in the middle of the line that is vertical is the valve that you cant see unless you feel for it. Hope that helps you
Ron