DC Heating Element for Attwood EH 11?

[CapnCrunch]

Does anyone know if there is a 12v DC heater element available for an Atwood EH11-sm water heater? Or is it possible to just use the 110v one the
at came with the unit?

TIA
Gary

[GordMay]

1. Yes, and 2. No.

To calculate the wattage required to heat water in a tank:
Watts = 3.1 x Gallons x ΔT (in °F) ÷ Heat-Up Time (in hrs)
Hence, to heat 6 gallons of water 45°F (from 75° to 120°F), in 1 hour:
Watts = (3.1 x 6 x 45) ÷ 1
= 837 Watts (≈ 67 Amps @ 12.5 Volts for 1 hour) (or 837 W/Hr)

1a. You can get dual voltage/dual wattage [500W/120V & 300W/12V] elements.
➥ https://www.jgordonco.com/product-de...?cpm=854&cat=2

1b. You can also get 12 Volt elements.
➥ https://www.dernord.com/products/12v...ith-1-inch-npt


2. A typical 1500 Watt 120 Volt water heater element is ±9.6 Ohms [cool]
Powered at 12 Volt [DC] the 9.6 Ω element will only produce about 15 Watts of heating. [W = V² ÷ R]

[SailingHarmonie]

While it is POSSIBLE to use the 110V element,b it will not hurt anything, but it will not supply any useful heat, or even serve as a useful power sink for a dump controller.

An 800 Watt element designed for 110V will pas a current of about 7.3 Amps, and have a resistance of about 15 Ohms.

Connecting a 12 Volt supply to a 15 Ohm resistance will pass 0.8 Amps, for a grand total of about... 10 Watts. Totally worthless for just about ANY reason you might want to connect it.

Very few boats have enough 12V DC power to actually heat water in a useful fashion. Does this really fit into your power budget???