I think the four season, three season thing can be argued about if one would want to but, as others have said. if you have a heated underbelly, it should have enough heat in there to not freeze your waterline with the furnance running. I'm not talking about camping year round in the artic! I'm talking about getting caught in a Alberta clipper in southern Texas. The water should not freeze from the pump to the inside tank. It is not rocket science here. I'm just asking Heartland to either extend there 2 inch duct, that is suppose to heat this area, farther back into the belly where more heat is needed, or to better insulate this line! The other night when it was 10 outside, it was 27 underneath, and of course the water was froze. NO matter when we kept the furnance running all the time the temperature under there never came up from 27. This clearly shows that not enough heat gets to where it should go. We are currently parked in a rv park where there are a lot of old campers and a few newer ones, but as far as we know, we were the only one with frozen water? Does that tell you something, our rv was 3 weeks old. In this forum, I have read posts about this problem that date back to 2007, and Heartland haven't changed anything. We are not talking about spending thousands of dollars here, I bet at the factory they could fix this problem in minutes, when the belly is exposed.