DC Electric Water Heater with Heat Exchanger

charlesrg

Member
I'm wondering if anyone found a system with heat exchange and coil while the coil runs at 24V DC.
I'm picturing running the water heater straight from the 24V Battery bank instead of having to turn on the inverter.

I researched on the brands bellow and all have only 110V/220V heat elements:
  • Webasto
  • Torrid
  • Whale
  • Kuuma
  • ITR Heat
  • ISOTherm
  • Truma
The only one I found to have 24V DC element is the Elgena but only at 400Watts (https://www.elgena.de/products/nautic-therm?variant=14802382851)

With around 1000 watts element I could have a small tank that and be able to shower in not so cold days without having to turn on the diesel coolant heater.

I understand I will need a heavy gauge wire to the heater, however I feel that is better than having the inverter as a dependency.
 

LandCruiserPhil

Expedition Leader
Have you considered an engine coolant heat exchanger with electric back up. I have found it very nice to have hot water just by driving and Elgena makes one.

I wanted something smaller than the Elgena and something I have quick access in the USA to all the parts if needed. My 1gal 12volt 200 watts water heater will heat water at 1.5° degrees per minute per gal.
Pictured my prototype 1 gal water heater.

1604099160746.png
 

john61ct

Adventurer
Do not bother trying to heat water using stored electricity, consumes **way** too much power for off grid

And low voltages means tiny watts, it will take many hours to heat even a low volume of water.

even if running directly off a genset, it's super inefficient compared to using propane, or directly burning the fuel your vehicle uses.

If running a water cooled engine, use a heat exchanger (calorifier) off the coolant loop while driving.

If you get a **lot** of solar up on your roof, so much that you generate a lot of "free excess" power that would otherwise get wasted,

just as with running aircon,

it is "possible" to heat water that way

but that rarely is the case from a practical POV.

However, putting a black metal or plastic container of water out in the sun works very well, aka at its simplest google "solar shower bag"

 
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Peter_n_Margaret

Adventurer
You could power a 1,000W+ 110/220v immersion heater from an inverter anytime while the engine is running.
Inverters are cheap and AC heaters are cheap and readily available.
We can often run a 240V/1,000W immersion element from our 1,300W inverter powered by solar and batteries when camped up when the sun shines.
Cheers,
Peter
OKA196 motorhome
 

RAM5500 CAMPERTHING

OG Portal Member #183
You could power a 1,000W+ 110/220v immersion heater from an inverter anytime while the engine is running.
Inverters are cheap and AC heaters are cheap and readily available.
We can often run a 240V/1,000W immersion element from our 1,300W inverter powered by solar and batteries when camped up when the sun shines.
Cheers,
Peter
OKA196 motorhome
Not Possible! Some guy above says so! :p

But yes, I am doing the same! :)
 

burleyman

Member
I use a Camco 120vac 1000 watt heating element with an attached power cord occasionally, immersed in water-filled plastic containers. Don't do this. Use at your own risk. Danger of electrocution. Always in water before powering up. Different wattages available at 120vac. Used in many RVs.


1000 watts equals less than 10 amps at 120vac from inverter or shore power. Battery/inverter means approaching 100 amps DC from battery power. 10X.

For 12v DC, 3D printer heaters provide decent wattage for size. I have a few of these. Heats up coffee quickly. Both 12 and 24vdc available.

 

charlesrg

Member
Have you considered an engine coolant heat exchanger with electric back up. I have found it very nice to have hot water just by driving and Elgena makes one.

I wanted something smaller than the Elgena and something I have quick access in the USA to all the parts if needed. My 1gal 12volt 200 watts water heater will heat water at 1.5° degrees per minute per gal.
Pictured my prototype 1 gal water heater.

View attachment 621776
How's your prototype going ? I've been debating also creating one, principle is pretty simple, another method would be to just replace the element to 12V or 24V.
Do you thin you will need to add an anode to yours ?
 

charlesrg

Member
Elgena makes a Dual Element heater, 12V/24V + 220V + Heat exchanger. However their AC element is 220V only and I needed 120V.

The reason that I want to do 24V + Heat exchanger is so I can just maintain the hot water with a heat element after the engine heated it.
24V so I don't need the inverter running. My offgrid build has most of it's components running natively at 24V, inverter can stay off most of the time.
 

charlesrg

Member
I reached to Elgena, if I can run their Dual element at 110V that will be awesome.
400W @24V DC
500W @120AC
+ Engine Heat exchange.
 

LandCruiserPhil

Expedition Leader
How's your prototype going ? I've been debating also creating one, principle is pretty simple, another method would be to just replace the element to 12V or 24V.
Do you thin you will need to add an anode to yours ?
Performance-wise its a working unit and 1 gal of 190° water goes a long way. The mounting and me taking the time to finalize details is all needed. Testing shows ~1.5° per minute - Take 70° ambient water and in 20 minutes you have 100° using ~15 amps. It will be 100% SS so Im not sure if an anode will be required? If one uses a prefilter or RO water I would not think an anode would be required. To my knowledge, Elgena does not have an anode.
 

john61ct

Adventurer
For 12v DC, 3D printer heaters provide decent wattage for size. I have a few of these. Heats up coffee quickly. Both 12 and 24vdc available.
Note the 12-24Vdc seem to max out well below 100W

take a long time to heat up shower water at that power rate
 
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