Converting Class B to 4 Seasons

With a Class B a lot depends on the design and placement of the plumbing. Most Class Bs are not designed to allow for tank heaters, etc. The easiest thing to do is be prepared to winterize as soon as you get a weather report of freezing temps where you are heading or where you happen to be on a winter trip. You can still travel in your Class B in the winter in freezing temperatures and no water in your plumbing. Drink bottled water, wash using bottled water and a basin fit into the sink that will get dumped at a restroom, and flush using antifreeze poured from the bottle or put into your fresh tank and flushed through the pipes as usual. Your grey tank will remain empty and your black tank will only have waste and antifreeze inside. Even with $3 a bottle antifreeze this is not cheap to do, but it will save your pipes from damage. Once you head back south where the temperatures are well above freezing you just de-winterize and flush the plumbing.

My Roadtrek has both an exterior and an interior fresh tank and is supposed to be able to go to 14dF using the interior tank only - but that is with interior heat maintaining "room temperature" 24/7 - and the waste tanks also need antifreeze in them to keep them from freezing. It is not really practical.