Ken-
As Cookie said the drains have been deleted from current models, due to prior freezing problems.
The "old" low drains had open/close valves sticking out the bottom of the enclosed cover, so owners could access the valves for operation. This allowed the outside cold air a place to easily reach the lines and this was the first place to freeze. Kind of a "catch-22" situation.
Heartland removed the valves due to freezing, so now there is no "easy" draining method just for the lines. Like Mike said, remove the water heater rod and let the heater tank drain.
Of course the fresh water tank needs to be drained and there is still a low drain valve and when it's opened the fresh tank will be cleared. (On mine it's directly next to the sewer tank connection under the body of the unit.
BUT........ the cold & hot water lines probably still have water in them, and yes, those could freeze if left there in cold weather, and yes are at risk of breaking. If left long enough, in cold enough weather, I would imagine all the plumbing system, including fittings, etc., are at risk.
If I'm leaving the trailer for a few days, and it's going to be freezing weather, I drain the fresh water tank, drain the water heater, and put compressed air through the hot/cold water lines to blow them out. I have a fitting that screws into the fresh city hook-up (the other end of the fitting has a fitting to match my compressor line), open all the water facet valves inside the trailer, and push out the water with about 50 psi of air.
Hope this helps,
Chris
