Yes, just don't make any demand for heat from any faucet while you have the hose disconnected. I run my HH in the cold while it's sitting next to the house, just to keep the basement warm until I winterize it. Not using any water. Tank is empty and not hooked to a hose.
In case you don't know, you can't get all of the water out of the lines and the copper coils in the HH. That's why it's a good idea to NOT just blow out the lines as a winterizing effort. HH and AH owner's pump the pink stuff into the water lines instead. That way, the liquid at the bottom of the coils will not expand under freezing temps and cause a rupture.
The best way to do that is to get a 48 in washing machine hose (the silver braided kind available in a any hardware or big box store). The fitting is an exact fit on to the inlet of your water pump. Screw the braided hose on to the water pump and stick the other end in the gallon jug of the pink stuff. Have someone inside the coach turn on each faucet (with the water pump on) and let it run until the pink stuff comes out. It critical that your helper inside run both the hot and cold at each faucet. That will make sure the pinks stuff is in the coils of the HH. You have to plan ahead for what your procedure will be as the gallon jug empties (quite rapidly). Becky and I use walkie talkies and I just yell "stop" (meaning stop the water pump) when I need to change to a new jug. For me, with the four faucets, the toilet, and the washing machine (a separate procedure...read the owner's manual), it runs to 3 gallons +. $2.58 a gallon yesterday at Wally World and you are safe.
