Just bought a 2018 3160EL. Heartland website says I have one gray water tank but there are to two gray water dump handles in my UDC. There are two separate 1 1/2 inch pipes feeding the 3" main pipe so you would think there are two tanks. I ran anti freeze in the kitchen sink and the shower. When I pull the lower gray water handle in the UDC nothing comes out so it makes me question if there are two tanks or is the valve broke. Any insight on this would be appreciated.