In my GT 325, the switch, labelled "Artic Pack" is on the front panel of the kitchen cabinet by the sink. I have the manufacturer's user guide for the system.
The heating elements are attached to the underside of the black and grey waste tanks. They have built-in thermostats (non-adjustable) that switch the elements ON at 40F and OFF at 65F when the system is energised. They are 12vDC elements and each draw about 7 amps.
I can't see the need to heat up my sewage to 65F, nor can I see any need to send 14 amps to a couple of small patches on the bottom of a plastic tank. Based on my recollections of high school science that discussed the effect of contaminents on freezing point, I can't see either the black or grey tanks freezing up at anything less than a prolonged 28F or lower. I also don't like the idea of those two small patches melting though the plastic tank, if it happened to be empty!
BTW, to a Brit, like me, an "Artic" is an 18-wheeler truck/trailer rig (an abbreviation of "articulated lorry"). The label installed by Georgetown should really say "Arctic".
I think, if you're a regular camper in cold climates who uses on-board potable water, maybe an element similar to frost tape, with a matching thermostat couls be attached to the freshwater tank.
My rig was optioned with this system by the original owner. I don't plan to ever switch it on.
Frank and Eileen
No longer RVers or FR owners