Road shower water heating

mep1811

mep1811

Gentleman Adventurer
Just got married and to help my wife to enjoy camping I purchased a Road Shower. I like that it is a no set up shower system. I know the heating ability is limited to hot summer days.

I have been figuring out how to best heat the water in less than optimal conditions. One idea was to pour boiling hot water into the tank just prior to the shower. I don't think that would work well.

My second idea is to use my Zodi how water heater to circulate the water and heat it. The issue with that is both intake and output hoses would have to use the same fill opening and the same water would be heated and not circulating very well. I guess after time all the water would be heated up. I could try to use one of the outlets as the water intake but the pump would not fit.

If the Road Shower had two fill openings then I think the Zodi would work better. Or fill the tank with the Zodi from a water can and pump the hot water into the tank.

My last idea is using a 12VDC submersible heating element . Ideally an element could be an integral part of the shower but I would put it into the fill opening. I know this would take some time to heat all the water but could be put in when stopped and have a shower ready afterwards.

I've experimented with a bug sprayer shower using a similar element. It heated two gallons of water to scalding in a few minutes.

I'm interested if anyone else has approached this with any success. Thanks


https://www.amazon.com/Watt-Submersible-Water-Heater-Element/dp/B00KLKGJ1I
 

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Herbie

Herbie

Rendezvous Conspirator
I don't think the math is going to work out on the heating element.

See here for the source on my formulae, so you can check my work, but:

Formula for heating water inside tank:
Gallon Per Hour (Electric) = (KW x 3413) divided by (temp. rise x 8.25)

You're proposing a 300W heating element (.3 kilowatt). To raise your water from 70° to 110° (nominal daytime ambient temp to hot shower") is a 40° rise.

So:

.3KW x 3413 = 1023.9
40 degree temperature rise x 8.25 = 330

1023.9/330 = 3.103

So that element can heat 3.1 gallons of water per hour. That's purely electric input, and does not account for cooling due to radiation/conduction/convection of heat back out of the tank since the Road Shower is not insulated.

The Road Shower is 4 gallons, so right there you're already kind of in a losing battle, as you'd have to run the heater for more than an hour (fighting losses along the way) to get that 40° rise.

Secondarily, your 300W heating element, at a nominal 12V, will demand 25A continuously. We could be generous and say you're running closer to 12.75v, but that's still a current of 23.5 Amps. Ignoring the heat loss above, you'd need to run for 1.28 hours to raise 4 gallons by 40 degrees, so you're talking about (1.28 x 23.5) ~= 30 Amp-Hours, at a bare minimum.

Realistically, unless you have a phenomenally large battery bank, your operating voltage will start to drop as you pull those heavy amps, so expect to see a big fall-off in the heat-output of the element towards the end. The voltage will trend down below 12v under such a big load, so you'll be generating less heat, which means you'll need to run even longer to raise the temperature of the whole 4 gallons to the target temp.

So, I guess you could build such a system - with a dedicated 100AH or so deep cell battery, LARGE cables, breakers, etc. Presuming you started on a not-too-cold day, and had an about an hour and twenty minutes to wait, you could just about get a single hot shower out of it. Your battery would be 60% depleted of it's usable charge (remember that discharging below 50% capacity radically shortens a battery's life, so a 100AH battery is good for repeated 50AH discharges only).

If it were me, I'd try to find a way to use the Zodi in a way that worked better for the experience. Recirculate into a jerry can or bucket, and use an inexpensive 12V water pump to run the shower.
 
C

CampStewart

Observer
Since it is going to be attached to a vehicle I would strongly look at a heat exchanger using your engine coolant to heat the water. There are a number of buildups on this website. I am most impressed by the writeup I read where the guy used a mixing valve to control the water temperature.
 
Coachgeo

Coachgeo

Explorer
hmmm..... why a shower?

Seriously..... that is soooooooo old school

actually... am serious.. they don't shower in space..... they don't shower in Re-Hab centers..... and they don't shower in Hospitals.. Yet all the folk in these places.... are washed clean daily.... They use No Rinse cleaning solutions.

A nice warmed solution of No-Rinse washing liquid and be done with it. Put it on your wash cloth (or adult wipe) and clean off. Your done. If your extra grimy in some spots start with a 2-5?% solution of rubbing alcohol. A shower's purpose is only too rinse off the dirt/grim/germs/oils lifted to top by soap which is a surfactant (bring to top) solution. That you must rinse away.

No Rinse wash liquids ... does not require a rinse.... it only needs a wipe off to remove the dirt/grim/germs/oils https://www.amazon.com/Clean-Life-P...0SOOICO?tag=pda0d8-20&camp=1789&creative=9325 Gallon of this concentrate as your main wash solution can last you a few years if you only camp total few months each year. You can use your water for drinking and cooking. You might use 1% of your past water use for body washing to mix with this concentrate. They make no rinse soaps for hair too. Makes my sensitive bald ******** head itch too much though....

So... warm space, warmed No Rinse body wash, and your golden
 
Coachgeo

Coachgeo

Explorer
CampStewart said:
Since it is going to be attached to a vehicle I would strongly look at a heat exchanger using your engine coolant to heat the water. There are a number of buildups on this website. I am most impressed by the writeup I read where the guy used a mixing valve to control the water temperature.
Click to expand...

got a link or some ideas for good search terms to help find this on this board? When using ( water, "heat exchanger" "mixing valve") I get couple pages of results.
 
Semi-Hex

Semi-Hex

Enfant Terrible
We've had our for four years now and couldn't be happier. We seldom have to add hot water from the stove but I have to tell you, that if you are sweaty from a hike there is nothing better than a quick rinse. The bugs are fewer if you don't have that grungy smell either.
 
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