I have a 2013 Eagle 31.5 RLTS, & have one vent in the living area, one in the kitchen area, one in the bathroom & one in the bedroom. My 5th wheel is supposed to have the Climate Shield ultimate weather protection that is supposed to protect from 0 deg. F up to 100 deg. F, & also says the underbelly is fully enclosed and heated!!! I can access the back of my water heater where the bypass is but will have to check with a tech to find out how to access the back of the furnace to check if the underbelly is actually has a duct near the holding tanks. Also remember that if in freezing weather, you'll need to use your fresh water tank even if at an R.V. park cause some actually turn off there water so there not damaged from freezing and if they are insulated well you would need to have a heated water supply hose to hook up to your R.V. or you'll find out like I did that the water supply hose and my inline filter froze up, lol!!! It was in Elko, Nv. and didn't think it was supposed to get that cold overnight on our overnight stop on the way to Ca.
THE INFORMATION QUOTED HERE BELOW IS DIRECTLY FROM THE JAYCO EAGLE TRAILER & FIFTH WHEEL 2013 SALES BROCHURE:
Ultimate Weather Protection
Extend your camping season. Offering weather protection against extreme temperatures(as low as 0 deg. F or as high as 100 deg. F), the Jayco Climate Shield combines the industry's most-protected underbelly with the class's highest-BTU output furnace. The enclosed underbelly, tucked and foamed inside the I-beam rails, features blown heat for the ultimate four-season camping experience. Testing cannot account for natural elements, such as wind or moisture. In actual use, unit may not perform as well. In addition, outside components are subject to freezing and require steps to properly insulate. Jayco's warranty does not cover damage caused by freezing.