How important is it to have a heated under belly (enclosed underside) if you're camping in cool ( freezing a couple of times a year) weather. As long as there is heat in the TT will that suffice to keep inside lines from freezing? I realize that the water coming in may freeze outside of the TT. Your opinion?
The heated undercarriage is for the holding tanks. It helps keep them from freezing in cold weather. I would not want my tanks freezing and/or bursting then having to clean up the mess plus put out the money for new tanks. We will not have a unit that does not have heated tanks, will not take the chance for even a couple of times out. JMHO
Usually, if temps get down to low 30's, high 20's at night, it won't be below freezing long enough to freeze tanks and lines. If you have a low of 28 degrees, the actual temp. isn't that low for very long. It takes awhile at that temp. to freeze things. Other factors such as wind chill can enter the equasion. While you are camped with the heat on is one thing. Think about towing over a mountain pass with exposed water lines where you may have the heat off in the trailer, you have significant wind chill from your towing speed, if nothning else and possible, below freezing temps. Even then, a few hours many not freeze things to the breaking point but a long trip could create problems. Your hot water heater is exposed. Do you leave it on? If it was full of hot water, it is pretty well insulated but it is outside the trailer so, even if you have heat on inside, it is not protected. Even with heat in the trailer, the wind will negate its benefit for exposed water lines below the floor. I guess, bottom line, temps. below freezing won't hurt you, short term, it's how long they are below freezing that you have to consider. A few hours, usually not a big deal. If it doesn't get above freezing for most of the day, you are probably going to have problems with exposed tanks and lines.