Back in MD we used our ACE in sub freezing temps often - mainly prepping to leave for warmer weather. But we always had to endure the gauntlet of coming and going in very cold temps. Like 10 degrees. I refused to run the unit winterized as it really bothered me to defeat the purpose of owning a MH in the first place. A self contained house on wheels. As long as the heat is running I never had an issue with pipes or tanks freezing. The real issue for us was the water pump as it sits in an outside bin that has no heat and is un-insulated. The quick and easy fix was a small space heater but a light bulb will do the trick as well. You only need to keep it above 32. As others have said, most modern RV's heat the pipes and tanks via the ductwork. Blow the water out of the outside shower and take the handle off. That one got me every time. Other than that, I never had a pipe or tank freeze.