gray/black/fresh water tank heaters - 12v or 110v?

[jeeplj8]

looking at these for tank heaters:
2ea RV fresh gray black water holding tank heater 12v | eBay

Question 1: should I get these 12v or look for 110v model?

Question 2: how many would I need for:
-30 gallon fresh
-30 gallon black
-10 gallon gray

[mtnguy]

Any kind of heating element is going to deplete your batteries quickly if you are not hooked up to a power source. On initial thought, I thought the 12 volt heaters were not a good idea, but they may work going down the road when you are plugged into your TV. At 80 watts each, I am not sure you could run all 3 at the same time, though....they are drawing almost 7 amps each (@ 12 volts) .

[jeeplj8]

I think I would need them to run going down the road. We will be towing for about 8 hours Thanksgiving, and I expect temps to be pretty cold that night (when we will be driving.

I am not sure what the amp draw is on the TV power feed. If I recall correctly it is at max 20 amp, so it would run 2 at the same time. But then if insulated, they should not be running constant, only intermittent.

I have seen some which are dual voltage, but they are about 3x as much money.

Either way - they would only run when either I am on shor power or on the TV.

[Momma Tac]

This website may help you: UltraHeat, Inc. - FAQs
Just remember there needs to be liquid in the tanks before using the heaters, so if tanks are empty when going down the highway, heaters are not to be used.

[F and E Damp]

We have Georgetown's optional Arctic Pack (was on the rig when we bought it). Those elements are 12V and include a thermostat. Having read the "blurb" I doubt I'll ever use them. When they're turned on at the switch, the thermostats switch the elements on if the temp drops below 40F and they stay on until they reach 65F.

I honestly don't think the sewage in the black tank will freeze until the temp gets quite a ways below 32F and why would you want to "cook" it to 65? The potable water tank isn't protected.

[jeeplj8]

Originally Posted by Momma Tac

This website may help you: UltraHeat, Inc. - FAQs
Just remember there needs to be liquid in the tanks before using the heaters, so if tanks are empty when going down the highway, heaters are not to be used.

I would think it would be best to install with a rocker switch for each heater. So you could keep the fresh water tank on and not have the other tanks come on until you actually need them.