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Electric Hot Water, is it a reasonable option?

14K views 44 replies 18 participants last post by  ray538 
#1 · (Edited)
After much consideration it may be. Two methods I've brought up in other threads seem viable at this point.

1) I had become enamored with a DIY design based around a 12V 100W heating element that would be installed in an insulated storage tank. This would be controlled by relays to heat the water any time the engine is running, and, on demand by thermostat when the House Battery Voltage was at or higher than some set point.

It would require a lot of fabrication and design for the control circuitry, the tank, the insulation, but it might make an interesting project for someone with the time and the inclination. I'm not sure I'm so inclined after considering the time this will take to build and test and fine tune.

Which leads to Door Number 2, next to where Carol Merrill is standing ...

2) Siogreen's Model I30-POU Tankless water heater. (~$200 on Amazon)


At first glance it appeared that the 3.4 KW rating put it out of the running, as that exceeded the rating of the inverter's AC output. This was pointed out in another thread some time ago where I suggested this device, and I had dismissed the idea at that time.

Further research revealed how the unit has (from their Amazon page):
Manual - 4 Power Levels

IR30 POU operates in manual mode with 4 power levels from 1 to 4.
You can adjust the current from 8-28 amps resulting in 0.85kW to 3.4kW of power so that it fits any application. (my emphasis)


End Quote


Now, this setting isn't mentioned in their manual. I have one of their units installed at home that shares the same instruction, so, have some familiarity with the controls.



I called to ask about this elusive feature and was told how the secret to changing these settings is to hold down the Up arrow (usually used to adjust output water temperature higher)* for a couple of seconds, and it switches the readout to level-setting mode where you can choose between power levels 1, 2, 3, and 4.

*Correction: After writing this up I tried to access the settings on the unit installed in the house. It is actually the Power button that must be held in order to switch modes. Then, not 4, but 8 different levels are available to select from. Though this is a higher output unit and the one for the van may only have 4 settings. Looking forward to finding out.



Which, based upon the amp range above, I'll consider to be as follows:

1 = 8A

2 = 15A

3 = 21A

4 = 28A.


At 8 Amps/120VAC it uses 960 Watts. On the 12V side this translates to 80 Amps. For 5 minutes of actual use (1/12 hr.), 6.6 Ah. The water may only be marginally warmer, but electrically it would be a very frugal way to get a warm shower.


At 15 Amps, 1800 Watts. This translates to 150 Amps at 12V, or, for 5 minutes of actual use, 12.5 Ah. Warmer and still not a huge hit on the House reserve, nor does it exceed the rating of a 2000W inverter.


At 21 Amps, 2520 Watts. Translated, 210 Amps at the battery (perhaps exceeding some batteries' delivery rating), and for 5 minutes of actual use, 17.5 Ah.


Each of the above examples are ballpark and do not factor in losses in the conversion from 12DC to 120AC.



By "actual use" this is based on taking a shower where the water will be turned on and off to conserve the water supply. A ten minute shower may have less than 5 minutes of actual hot water usage.


This is looking better and better as a source of hot water for the build. Particularly with the advantage that the Power setting can be changed when I am on Shore Power and run the unit at max. (though, frankly, if I'm on Shore power there is probably s shower nearby with unlimited hot water)


If my numbers are right, I figured this might be of interest to others, and a good idea to share this new information.
 
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#2 ·
Just completed my shower water heater. Used a fabricated 14 ga. 6 gallon SS tank that also serves as the portapotti pedistal to bring toilet up to the correct height. Installed a 120 v AC 625 watt "10 gallon" RV propane to electric conversion kit. Kit includes a thermostat. Fill the no pressure tank manually and use a DC submersible pump to get water out of the tank.

Works very well for a shower. With 61 degree water it takes 45 minutes to raise the water temperature to 90 degrees. Tank is not insulated so water only heated when shower wanted. The water is all at one temperature so no hot/cold water mixing and no plumbing.

The power can be supplied from three sources. Shore power, "shore power" from the vehicle powered inverter or power from the house inverter/battery. Engine must run for the vehicle powered inverter to be used. Using the house inverter/battery will use about 10% of the 255 amp-hr house battery. Using the house inverter/battery depends on the weather conditions to be sure I will have excess power available from the 300 watt solar panel.
 
#3 · (Edited)
  • It was reading about your costs for the custom SS tanks, your's and others' use of propane, a 20 to 45 minute wait for heated water in various systems, and the to-be-expected high consumption of battery resources that led me on this quest.

This unit:

  • is tankless and heats water instantly and on demand
  • only runs for however long you have the tap open (reducing load on the battery to the minimum necessary to heat the water used)
  • installs with three wires, three screws, and two pipe fittings (no fabrication required)
  • uses from 3.3% up to 8.75% of a 200Ah battery's supply depending upon the power level setting and water temperature setting
  • is electric only, no Propane
  • has a total cost of $200.00
  • best of all, small footprint


Thanks for posting your latest upgrade to further exemplify more specifically how this device is different from what I've read about before.
 
#4 ·
Travlin', I've thought of fabbing up Orton's idea but I have way too many arns in the farr. :D Also, I've used a couple of the cheap Eccotemp (I think, from Amazon) propane tankless water heaters and was always unimpressed. The problem is the frugality with water that camping necessitates. We used one with a Sportsmobile and a 25 gallon water tank but were still taking quick showers turning the water on and off as we wash to conserve as much as possible. we found it nearly impossible to get a steady flow of hot water with the propane type. It would be scalding or freezing, usually going back and forth every few seconds. I would love to hear whether or not this electric model is a bit more 'even'. I love the idea that you can adjust it's power consumption.

Keep us posted please!
 
#7 · (Edited)
That is a good point to consider. I will provide more data, once I get that far along.

We have the IR-288 model of this same brand installed at home. 6KW at 220VAC. A little less than twice the power.

It provides hot water to either the kitchen sink OR bathroom sink OR the shower. Opening more than one exceeds the flow setting for best heating efficiency. Flow is regulated by a valve on the unit output that you adjust for water to pass through at a rate allowing it to reach the set temperature before heading downstream. I'd guess we are using it at 1 or 1.5 GPM, which is more than enough for any of our uses, as it makes very hot water at that flow rate. If more than one tap is opened the water is still hot, but now the pressure is split between faucets.

We have it set at 50 C, which is 122 F (because it only provides degrees C on the display). We had it at 60 C (140 F) and that was much too hot. I've been impressed with how well it works after dialing down the flow rate. I think this output temperature setting will help prevent the scald or freeze scenario you describe. Just set it at 100 F (37 C) and run it.

Because it is a long run from the heater to the bathroom, once the water is there I have to turn down the hot and add cold water because it is plenty hot for me. But, there's not an easy way to test it at home like you describe because of the hot water that remains in that thirty or forty foot run between heater and shower.
 
#6 ·
I already purchased an Eccotemp so will try it first. I understand that unit takes a couple minutes of running water to heat up so I plan to set up a valve circulating water back into the fresh water tank so no waste of water. Once the water flow is heated up I can have hot water at the sink for dish washing or for my wife to wash her face at night. She wants warm water or I must travel alone :)

I hope the above approach works. The advantage is no need for electricity. If it doesn't work I'll try a Bosch mini-tank water heater. It's similar to your approach (electrical heater element in the tank) but it has good insulation built in. From what I read it's very efficient insulation. I may have a switch to only turn on when driving or when there's good solar power. Once a full tank is heated up it'll likely be enough for my use for a day, or there is a 4 gallon version available.

What do you think of this option?
 
#8 · (Edited)
I was looking into that, and a few others like it, but the physical size didn't fit my layout well. After reviewing the parts diagram for it I considered how replacing the AC high wattage heating element with a 100W 12VDC element, then setting it to run whenever the engine was running, or, be switched on manually might provide something very close to item 1 in the original post, above.

The Bosch looks like a well designed unit and another builder has one in his van. There is still the aspect of planning ahead to heat the water before you need it. I'm hoping the on-demand rig will help with that.
 
#11 ·
After much consideration it may be. Two methods I've brought up in other threads seem viable at this point.

1) I had become enamored with a DIY design based around a 12V 100W heating element that would be installed in an insulated storage tank. This would be controlled by relays to heat the water any time the engine is running, and, on demand by thermostat when the House Battery Voltage was at or higher than some set point.

It would require a lot of fabrication and design for the control circuitry, the tank, the insulation, but it might make an interesting project for someone with the time and the inclination. I'm not sure I'm so inclined after considering the time this will take to build and test and fine tune.

Which leads to Door Number 2, next to where Carol Merrill is standing ...

2) Siogreen's Model I30-POU Tankless water heater. (~$200 on Amazon)

At first glance it appeared that the 3.4 KW rating put it out of the running, as that exceeded the rating of the inverter's AC output. This was pointed out in another thread some time ago where I suggested this device, and I had dismissed the idea at that time.

Further research revealed how the unit has (from their Amazon page):
Manual - 4 Power Levels

IR30 POU operates in manual mode with 4 power levels from 1 to 4.
You can adjust the current from 8-28 amps resulting in 0.85kW to 3.4kW of power so that it fits any application. (my emphasis)


End Quote


Now, this setting isn't mentioned in their manual. I have one of their units installed at home that shares the same instruction, so, have some familiarity with the controls.



I called to ask about this elusive feature and was told how the secret to changing these settings is to hold down the Up arrow (usually used to adjust output water temperature higher)* for a couple of seconds, and it switches the readout to level-setting mode where you can choose between power levels 1, 2, 3, and 4.

*Correction: After writing this up I tried to access the settings on the unit installed in the house. It is actually the Power button that must be held in order to switch modes. Then, not 4, but 8 different levels are available to select from. Though this is a higher output unit and the one for the van may only have 4 settings. Looking forward to finding out.



At 8 Amps/120VAC it uses 960 Watts. On the 12V side this translates to 80 Amps. For 5 minutes of actual use (1/12 hr.), 6.6 Ah. The water may only be marginally warmer, but electrically it would be a very frugal way to get a warm shower.


At 15 Amps, 1800 Watts. This translates to 150 Amps at 12V, or, for 5 minutes of actual use, 12.5 Ah. Warmer and still not a huge hit on the House reserve, nor does it exceed the rating of a 2000W inverter.


At 21 Amps, 2520 Watts. Translated, 210 Amps at the battery (perhaps exceeding some batteries' delivery rating), and for 5 minutes of actual use, 17.5 Ah.


Each of the above examples are ballpark and do not factor in losses in the conversion from 12DC to 120AC.



By "actual use" this is based on taking a shower where the water will be turned on and off to conserve the water supply. A ten minute shower may have less than 5 minutes of actual hot water usage.


This is looking better and better as a source of hot water for the build. Particularly with the advantage that the Power setting can be changed when I am on Shore Power and run the unit at max. (though, frankly, if I'm on Shore power there is probably s shower nearby with unlimited hot water)


If my numbers are right, I figured this might be of interest to others, and a good idea to share this new information.
I have the 4 Gallon Bosch Mini-Tank Water Heater in our van. It has work well as designed but required a lot of power (1300w) when running . The unit has good insulation but water temp decrease with time like any other tank heater. I would think the on-demand unit would be more efficient since it only heat the water when needed.

I did look into on-demand water heater unit when building my water system. All the power specs were so high that my 2000w inverter would not be able to run it. I did not know that the on-demand unit has lower power settings. That is very good to know. Thanks.

Let us know if the water temp would be hot enough for a shower at the lowest setting (800w) at say 3g/min water flow. If the output water temp is about 105F, I would definitely swap out my Bosch for this on-demand heater in a heart beat. My house batteries will be able to run this unit at anytime.
 
#12 ·
Let us know if the water temp would be hot enough for a shower at the lowest setting (800w) at say 3g/min water flow.
My first thought on reading this thread is that the lowest setting would not be sufficient, but that's a guess cuz I haven't done the math. However, it does not require 3g/min flow to take a shower, so a lower rate might work. It'll be interesting to see how this works out.

86Scotty said:
Also, I've used a couple of the cheap Eccotemp (I think, from Amazon) propane tankless water heaters and was always unimpressed. The problem is the frugality with water that camping necessitates. We used one with a Sportsmobile and a 25 gallon water tank but were still taking quick showers turning the water on and off as we wash to conserve as much as possible. we found it nearly impossible to get a steady flow of hot water with the propane type. It would be scalding or freezing, usually going back and forth every few seconds.
I've had similar experience. My solution was to circulate water from a tank through the Eccotemp and back to the tank, then shower with hot water from the tank.

Travlin said:
After reviewing the parts diagram for it I considered how replacing the AC high wattage heating element with a 100W 12VDC element, then setting it to run whenever the engine was running, or, be switched on manually might provide something very close to item 1 in the original post, above.
There are elements of higher wattage than 100W. I have a 300W 12V element in my DIY water heater and I've seen still higher wattage elements available (450W, if I remember correctly). Just FYI.
 
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#14 ·
Regarding flow rates and expected temperatures for those curious about the SioGreen Infrared Tankless Heater, this map and charts might be useful.

This is based upon average groundwater temperatures and operating at 3.4kW. Apply the chart to van use based on expected water source temperature at the heater's Inlet.



US MAP SIZING GUIDE FOR IR TANKLESS IR30 POU 120v



  1. Find your region color where you live and the cold water temperature inlet.
  2. Check the maximum flow rate output GPM (Gallon Per Minute) in the right table base on your region color.
  3. Use the Flow Rates Table below and check whether the outlet GPM in range with your fixture, or you need next size model.
  4. The outlet GPM calibrated base on set point range from 100ºF-107ºF / 38ºC-41ºC

Temperature Rise:
30ºF - 0.8 GPM
40ºF - 0.7 GPM
50ºF - 0.6 GPM​
 
#16 ·
@Travlin. Quartz tubes may not like vibration, bouncing down the road. Just don't know until you have it running for a while.
Base plate with vibration damners may help, but just not sure until tested. McMaster Vibration Mounts.

I'm looking at cheap water tanks based on a dune buggy aluminum gas tank.

https://shop.spunaluminumgastanks.com/8x33-End-Fill-725-Gallon-R833E.htm 7.27 gallon 8" x 33" $145.

316 area code, Kansas. They have optional flanges, fittings. I was thinking weld on two bungs (fill & button suction)
and fit a heating element into the cap fitting. $250 solution. Ya, it is aluminum. But for as often as I need it, it would be
tempting for the price.

For "camp showers" I like to rinse fast. Lather up then rinse again. I miss my shaved head as I could do all that with
less than a gallon of water.

Sink water will be from a 5-gallon jug inside the van (so no need to heat the water). Oh, I hate cold water for doing
dishes, but don't plan on using a lot of water to do them. Lots of people, then three pot dishwashing makes more sense.
https://blog.scoutingmagazine.org/2017/03/30/how-to-wash-dishes-at-campsite/
 
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#18 ·
[MENTION=61610]
and fit a heating element into the cap fitting.
Think the heating element needs to be close to the bottom of the tank so it is always covered with water.

I do not shower in the van like I do at home. The van shower enclosure does not have a door or a shower curtain. Door in not practical and a shower curtain would blow in the wind with windows open. The shower enclosure space is used for multiple purposes. At bottom is a shower pan and the portapotti. Above the portapotti is a hinged removable shelf that has two storage containers on it. Above the storage containers is a second hinged removable shelf. Upper shelf is at sink counter height to more than double my counter space. At the top are 3 removable towel rods.

To use the portapotti the two storage containers are removed and both shelves pivoted so they are back against back wall of the shower enclosure. To use the shower the two containers are removed, the two shelves removed and the 3 towel rods are removed.

Showering is not like a shower at home. Put towel down in front of the shower and first kneel down with head in shower to do the hair. Next stand in shower to do the rest of the body. Do not use a spray nozzle but instead use a full flow nozzle with on/off switch. Using full flow almost eliminates any over spray out of the shower. Odd procedure but you do get clean.
 
#20 · (Edited)
In our Sprinter, we have an Isotemp SLIM 4 gal marine water heater which uses the engine coolant loop to heat potable water while we drive. Takes about 20 minutes driving to make HOT water which will still be warm 6 hours later. Important feature is mixing valve since engine coolant can raise tank temp to over 200F. It does also have 750 watt element but we rarely need it. Mostly use that to keep water from freezing when parked at home on cold nights. We have a purge valve that lets water flow from the hot line near the faucet back to the tank. This way we don't waste water waiting for the hot to arrive. The heater is under the hood (wouldn't fit a Transit) so quite far from point of use. I will be looking at doing something similar on the Transit.

Now let's talk heated floors...
 
#24 ·
The cold water stays at the bottom of the tank while the hot water is at the top. Very little mixing occurs just as in your home water heater. As the water is heated it rises to the top which is where the output gets its water from.
In a 4 gallon tank you'll use it faster but it should be sufficient to wash with.
 
#26 ·
You might consider getting a 120v water hater tank and simply replacing the heating element with a 12v one. Will save you a lot of work. That’s what I did. While I never permanently hooks up the electrical, I got one with a heat exchanger and mostly use my running Engin to warm things up. It warms up in less than 10 minutes of motor operation and gets too hot!
 
#27 · (Edited)
I considered doing that, but couldn't find a place in my floor plan to put it. As this unit takes up minimal space, is already installed, and has been tested to confirm functionality, I won't be changing my mind at this point. :D



The instant-on aspect was a large part of the attraction for me. No need to wait, no running the engine, nor heating more water than I actually need. There is no insulated tank dedicated to hot water leaving more space to use for general storage. With on-demand I get exactly the amount of heated water needed, no more, no less, with no penalty in time, space, or excess energy usage.

It will require some awareness in operation. I have it set up with switched power, so when I want hot water I first turn on the Inverter, then turn on a dual light switch that both removes power from nearby outlets and provides power to the water heater to isolate the load. Also, the power level on the unit must be set to one appropriate for the inverter, though this should only need to be done once. It may take a little more presence of mind in operation.

For me, it is a good fit. YMMV
 
#28 ·
A simple solution for a 3 gallon Navy shower with warm water:

https://sprinter-source.com/forum/showpost.php?p=718054&postcount=159

My original shower water heater was a 6 gallon tank with the water heated with a propane to electric RV conversion kit. That works but a Sprinter owner suggested using a Monoprice Sous Vide 750 watt cooking water heating unit. Seen them on sale for $44.00.

The Sous Vide machine heats 3 gallons of water from 65 degrees to 95 degrees in about 20 minutes and uses about 20 amp-hrs of battery capacity. Unit is portable with heated water in a 14 quart Igloo cooler. When not heating water the Igloo cooler is my wastebasket. A couple hundred dollars for the parts.

This link shows the original shower heater and the new replacement:

https://www.ortontransit.info/shower-water
 
#29 · (Edited)
The Sous Vide machine heats 3 gallons of water from 65 degrees to 95 degrees in about 20 minutes and uses about 20 amp-hrs of battery capacity. Unit is portable with heated water in a 14 quart Igloo cooler. When not heating water the Igloo cooler is my wastebasket. A couple hundred dollars for the parts.
Good to know there is an alternative for those looking for a solution that takes longer to produce heated water, will always use the same Ah regardless of the amount of heated water actually needed, occupies a greater amount of limited space in a van, is portable rather than fixed installation, and will cost about the same. ;)
 
#30 ·
Portable and modular is GOOD.

Setting up a shower tent for extended stays is preferable to taking up space inside the van, which is already smaller than a prison cell.
 
#31 · (Edited)
Agreed!

The shower on my rig will be outside, between the open back doors, further reducing the use of inside space. A "shower tent" is planned that will enclose the area between the doors creating a shower stall, and will fold flat and store easily when not in use. It will also provide privacy and open for pass-through access. I'm considering a fold-down step/shower platform that would attach to the hitch, or a small folding deck to set on the ground.

The plumbing runs along the wall and the faucet has a 1/4 turn quick disconnect coiled hose with a garden-type sprayer. Being attached to a van is portable enough for my needs.

The 15' coiled hose/sprayer is stored when not deployed.

Here's the faucet and hose assembly.


This shows the faucet's footprint without the hose.
 
#34 ·
That is about 5Ah, correct? Very good efficiency! On par with the initial test I ran on the on-demand system.

That test produced about 4 gallons of ~100 degree F water and used around 15Ah. In practical use I expect that 1-2 gallons will be closer to what is actually used. If so, it may get by with 6 or 8 Ah/shower.
 
#33 ·
Travlin; that's my shower, too. I have a pole that I put between the two open rear doors that holds a shower curtain. I have a small slat platform I stand on so my feet don't get muddy. My "heater" is a Roadshower-1 at the moment, mounted vertically just inside the rear driver door, on my murphybed frame. I've considered using a 500w silicone heating blanket to warm it but haven't pursued it. I really like the portable instant hot water heaters with built in pump from Coleman and Mt Heater. A little 1lb propane cylinder is good for at least 4-5 decent length showers, and the water supply is anything you can put the intake hose into. Totally portable and free-standing.
 
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#37 ·
Navy Showers have been mentioned, but since the interior of a van is smaller than a prison cell, don't forget about Prison Showers; showering with your underwear on. I recommend running shorts with liners, they dry fast and allow you to get in there and wash stuff off, and don't look like underwear.

For people hosing off outside the back of their van who don't have a shower curtain.
 
#39 ·
For what it’s worth, I throw up a portable shower tent on my roof rack for quick Roadshower showers. Setups takes less than a minute. I get quite a bit of space. Room to leave my clothes. No mud. “Outside” of the van.

Not discrete, but so overly so that you feel confident in just owning it. I’ve tried showering in between the rear doors using a curtain, and it felt like a huge step backwards (for me, personally). Made me feel timid and apologetic, like I was breaking some rule.

I also intend to do a secondary hot water setup inside the van, but haven’t decided on the best course.


Sent from my iPhone using Tapatalk
 
#41 ·
#43 · (Edited)
I couldn't get the forum to accept the text without turning it into an embedded video link that didn't work. So I put quotes around it to kill the automatic function hoping some folks would figure out it out. How did you do it? I couldn't get it to work any which way. I finally copied your link back into the original post. Kinda took the laugh out of the post.
 
#44 ·
Yeah the forum is trying to help but mostly messes you up with links. The 'Share' arrow below the Youtube window shows a link that I copied and pasted. :D
 
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