I know my Seneca did not come with anything heated, and remote temp sensors ("tempminder") revealed that temps in the water areas are only 5 degrees higher than ambient with the furnace running. Usually, when you put heat tape on water lines you wrap them in insulation. If you can see the water lines in any bay, look at them and see if it looks like they are wrapped. Also, you would think this accessory would have a switch. If your not sure, as I wasn't at first, may be best to winterize and then take measurements of temps in different areas to ensure survivability in the cold weather. Also, the heat tape I installed also heats the water in the line, so you could try and feel the cold water and see if it feels icy cold or slightly warm.
Ryan, Maria, and Riley & Myla (Golden Retrievers)
2018 Jayco Seneca 37TS