Re: electronically controlled heated holding tanks
Look underneaeth your RV to see if you can see any of your holding tanks. If all you can see is a sheet of material that insulates your underbelly from the road and the outside elements, your tanks are considered to be enclosed. As far as the switch that seems to turn on your heating, it sounds like 12V or 115V electric heating. If that is the case, I would be leery of leaving your RV in very cold weather without being hooked up to shore power. If it's 12V the batteries would discharge rapidly, and if it's 115V you wouldn't have any electric heat. You need to check with a Flagstaff dealer to find out exactly how your heat is supplied to your holding tanks.
Like I said in my original reply if your tanks are heated by the propane furnace they will have heat supplied to them even if its not freezing outside, but cold enough inside to need your furnace on. I personally use a small 1500 watt electric space heater to take the chill off when its not below freezing outside. They work fairly well. I use a Patton heater made by Holmes. I like it because if it gets knocked over or falls it will turn off. Wal-Mart carries them for around $20. The only negative I know of for using an electric heater is that some RV parks will charge you extra if they know you are using an additional electric heater in cold weather.