Heating Water Backflow Devices in isolated locations for livestock tanks
I was tasked with an interesting problem. We have livestock tanks run by our water district that are in incredibly isolated locations. These water tanks fill from the bottom and are made of concrete. Replacing or modifying these tanks to comply with new state regulations pertaining to backflow and cross connection control would be extremely cost prohibitive. And the same would apply in running electricity to these sites. The backflow devices required for both the hazard level of the tanks as well as the applications (back pressure and back siphonage) would require a preventer that has to be installed above ground. We do insulate these devices and the lines feeding them with insulated boxes that provide a decent amount of protection from the wind and the cold, and everything will also have insulation directly applied to them. The problem I keep running into is the heat tape that we currently use to keep these from freezing draws quite a bit of power, and runs on AC. And as far as I know, the systems that would be able to provide the necessary power would be both large, and expensive. I am looking for a way to keep costs down as low as possible while also installing a system that doesn't require extensive maintenance. Does anyone have any idea what kind of output I would need to keep these in between 40 and 50 deg F constantly, day and night, wont drain a battery down to zero in the middle of the night and allow these rather expensive devices to freeze? Any ideas would be seriously, seriously appreciated.