all you need is a tank(metal or plastic), bulkhead fitting, 12v element
ref:DC Water Heater Elements

 

I think you are overthinking this. Like Phil says, just get a tank with fittings and a 12v element. You can setup diversion a ton of different ways, but you'll still most likely pull from the battery at times to make up for the solar losses. And by adding a second pump, you'll pressurize the system. The idea of taking it outside or filling with already hot water seems like a good idea in theory, but in practice you'll probably do it a few times then never again and you'll end up with a more complex plumbing solution than needed.

For ease of install, a bosch 4 gallon is pretty simple but runs at 120v. Either take the hit on inverter losses and get hot water faster, or go with a 12v system and get hot water more than 2x longer than with the bosch and a more complex solution. There are also 2.5 gallon units as well which is more than enough for doing dishes with hot water and a hobo bath.

 

another idea
IIRC this takes the standard everyday heating element available everywhere.

• leave as is (120v element) or
• find a short 240v element and run 120v thru it (IIRC it will run at 25% of it's 240v watt rating) or
• put a 12vdc element in it

 

That Bosch (and the 4gallon Rheem) Pull 1440 Watts, so that's ~130AMPS at inverted 12v supply - more current than I want to pull off my battery and more constant use than I want on my inverter.

If I could swap out that element for a 12v 300w or 12v 600w element and rely on the thermostat to still work, I would do that with the more square/boxy Bosch heater, but unless I'm mistaken, I don't think that switch out is possible.

For clarity, since it seems like you misread my description - I was never imagining removing my hot water tank from my van, just was thinking of leaving the water inlet available in order to "spot supplement" it with an infusion of hot water from other sources.

 

You are absolutely overthinking this. My shower water system almost exactly ticks your boxes.

The Shower Water Cartridges

MrNomer and I are 100% certain that we do not want any fixed plumbing in this van. Plumbing requires maintenance. Plumbing can spring leaks that are not found until they have caused substantial dam…

msnomersvan.wordpress.com

I haven’t updated my blog, but somewhere here about late May of this year, I described bow I can also heat water on the dash in one-gallon jugs pretty much as you describe. Paint one half with flat black spray paint. I lay them on the reflective side of my windshield cover. I've seen as high as 138°.

 

That doesn't tick several of my requirements - consider my wanting to take a shower or two or have hot water for dinner dishes after a day of skiing or a fall hike.

I want a way to take a hot shower (in a real permanent shower, from a showerhead) and to have hot water for washing hands and dishes.

MsNomer - you reply to an amazing number of threads and discussions with some version of "do what I did - it's the best". This is regardless of the fact that your situation and goals might have little or no overlap with the folks to whom you offer advice. For example, the two paragraphs which begin the blog post on your "shower system" are nearly the opposite of my situation.

MrNomer and I are 100% certain that we do not want any fixed plumbing in this van. Plumbing requires maintenance. Plumbing can spring leaks that are not found until they have caused substantial damage. Plumbing would be unhappy sitting at a trailhead in freezing conditions.

Our kitchen need for water is modest—coffee pot, cooking, and a bit for cleaning. This need is easily met with refillable squarish one-gallon jugs from the dollar store.

 

Sorry I offended you. Those who know me know I am a huge proponent of everybody doing their own thing.

Funny thing is, what caught my eye was your desire to shower after a hike, which is exactly what we do almost daily all summer. Heat water on the dash, insulated box with heating element—sounds mighty familiar to me no matter what shower enclosure you have. Carry on.

 

Those who know me know I am a huge proponent of everybody doing their own thing.

TOTALLY AGREE!

 

I was not offended I just have noticed that the frequent dynamic on specialty interest forums online is for a handful of "old timers" to become self appointed all-purpose advisers despite limited relevance.

Thanks to the suggestions of @phil and @nebulight I'm reconsidering buying an off the shelf 4gal model from home depot or Lowes, plumbing it in, then trading the heat element out for a 300W or 600W 12v DC element, wired like an excess dump load to the load terminals on my MPPT solar controller, but also switchable to the house battery. It would end up costing about the same as my above simple tank with extra pump, and wouldn't allow to adding infusions of hot water, but would be quieter, probably better insulated.

Has anyone here actually switched out the heating elements on one of these 2.5-6gal tanks to the 12v aftermarket models?

There's some confusion about if a replacement needs "normal" 1"NPT threads (Missouri wind and Solar) or 1" NPSM (natl pipe straight mechanical) threads On the Dernord/Amazon models.

Another specific relevant Question: - If you've pulled off the switch between 120v AC and 12v DC, did that fry the built in thermostat? Did you buy/install a replacement limit thermostat?

 

Has anyone here actually switched out the heating elements on one of these 2.5-6gal tanks to the 12v aftermarket models?

I've just seen videos like this one,
120vac to 12vdc water heater

There's some confusion about if a replacement needs "normal" 1"NPT threads (Missouri wind and Solar) or 1" NPSM (natl pipe straight mechanical) threads On the Dernord/Amazon models.

Pretty sure it's 1" NPSM, if it was NPT you wouldn't need a washer/gasket.
Anyway Richmond water heater screw in elements are 1" NPSM as per the parts catalog description.

 

I am going to have 600W of solar, and a 375AH battery bank and I am hoping to have enough hot water for dishes and a couple short showers.

I throw this immersion heater in this container with 1-2 gallons water and I have shower temp water (not super hot) in 45-60 mins. I have a three way valve before the pump so I can choose to pull water from either of my tanks. I've only tested it in the driveway and in the city so far but it seems like a workable system. I use the foam plug to save heat and keep the water from splashing out.
That heater is supposed to be 2-3000W at 220V but it works at 330-360W on 120V.

 

Another way is to use a 4 gallon marine water heater. It heats from the engine and also has a 110v element which could be substituted for the 12v element. This is what is used in the Rialta MH. By running the engine you recharge your batteries and also heat you water tank. After driving your water is at ~185-195* F, which last a long time.

 

And sometimes seeing a solution only vaguely similar to the original notion can enhance the creative production of the original notion.

I continue to post because I enjoy helping others create their own playhouses. I am fascinated by the enormous variety. I get a lot of positive feedback, but I’ve never seen another van like mine. I hope I never do.

 

You rock MsNomer.

 

Does this help ?

AquaH Marine Water Heaters | SPX FLOW

AquaH - is an innovative series of AISI 316 stainless steel water heaters, with a storage capacity of 22 up to 80 litres (5.3 to 19.3 gal.). Dual heating as standard - electrical heating and indirect heating based on a second heat source, for example the cooling system from the Marine engine or...

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500W 120v

Some inverters are 93% efficient (maybe better)

 

Please keep in mind this forum is about sharing ideas and resolving problems. A specific reply to your post only helps other who may have no idea what they are doing or need to do, to make a value judgement for themselves on what they need. Not all replys will be what interest you, nor should they be, but they may be valuable to others. Many people go way overboard when considering their needs, others are minimalists. Different approaches and methods may provide valuable information to others even tho they do not even remotely fit your needs.

i think some people need to see this again

 

<3 much love and happy, healthy new year @RV8R

 

@VanGuy

I see Pros & Cons to your idea. Like an unpressurized tank is drainable. The Con to that is the heating element (if run dry and let on by error) is quickly burnt out (at least with the ones I am aware of).

@el Jefe has been messing around with something similar & I wonder if he will chime in.

 

@VanGuy

I see Pros & Cons to your idea. Like an unpressurized tank is drainable. The Con to that is the heating element (if run dry and let on by error) is quickly burnt out (at least with the ones I am aware of).

@el Jefe has been messing around with something similar & I wonder if he will chime in.

I suppose I could chime in. This is not rocket science folks. Dump loads have been utilized as long as wind turbines, hydro generators and solar panels have been around. Pretty much mandatory with hydro and wind.

I can tell you that there are many van circumstances with 400 watts or more of panels on the lid that top up their battery bank long before the sun goes down.

Now, I am tired and the weather here @ Lake Pleasant here in Arizona and the weather is going brutally towards the freezing point.

The nice thing? I just took the top insulation panels off my two water tanks and the only thing I have to say about that is pure joy. We have no doubt that my solar dump load "messing around" will keep our sleeping quarters cozy all night. And it all starts over again as soon as the sun comes up in the morning.

Cheap too.

 

When one joins a forum and asks for help/advice one has to expect views that may or may not be welcome. This does not mean that any advice we receive should only be accepted if it meets our own preconceived ideas of "help". Sometimes it’s not only necessary but valuable to see how others see us. Whether we agree with or personally approve or disapprove of all the advice shared here it best to remember the spirit it’s given in. I see no advice shared here that was given with any ulterior motive other than to help.

 

I am way too lazy to work this hard for hot water.

If it were me and just for long weekend type trips, with the power system that you have, I might

• Buy a 30 gallon electric water heater
• Fill it at home
• Plug it in at home and heat it up
• Disconnect and pressurize it with a compressor (eliminates the need for a pump)
• Skip the whole auto water mix setup and use a few valves to mix hot / cold like we did growing up

30 gallons of hot water will probably stay warm enough for a 3 day trip.

 

I have been watching various threads for better ways to take a hot shower or heat small amounts of water. it doesn’t seem to be the easiest task. I thought missnomers approach looks like too much work to me.

I use a portable Coleman propane hot water camping heater. I installed a jack off my cold water supply tank to plug into the heater which I place on the ground behind the van. It is not a permanent system, takes a little bit of effort (2 minutes), but does supply unlimited hot water to a shower head attached to the heater. If I’m feeling modest, I hang a curtain between the two back doors to shower.

This allows me to have only one pump and one tank, but not on demand hot water. For a morning washing of the face, I throw a 12 V beverage heater into my yeti and have hot water for my face in about three minutes.

Obviously, it does not check all your boxes, but if you end up compromising, it is an alternative.