My 5er has a residential refrigerator and it's a 4 season, full time living unit, and sells with that advertisement. After last winter, realizing how much heat from the furnace pumped into the underbelly, I know why it can withstand temps down to zero.
However, in all their attempts to protect all the water lines ... um ... they missed one. It's the small line that runs to the refrigerator for the ice maker. It's actually in the slide, and about 2 feet of it is 100% exposed, no insulation, no nothing. Even if the ice maker in the refrigerator is turned off, and the rest of the camper is running water, that 1 and 1/2 to 2 foot of exposed line will still have water in it, and freeze, possibly break, and have no easy way to shut off forward of that exposed area.
May be advertised a 4 season 5er, but it's really not. Sorry Keystone, you missed it on this one by 2 feet! I winterize anyway with pink stuff.
