Shower hot water only- Bosch 2.5 gal electric or tiny camplux on demand ?

[Roktman]

Hey guys, so I’m putting the finishing touches on my 7 x12 cargo trailer conversion, the heater location is right next to the shower above the dedicated water tank behind tall 72 inch cabinet doors easy to get to and see, so I know the camplux on demand is for exterior use and if I go with it I’ll definitely have an exterior vent and small fan inside and mount it on a cement tile board of some kind , (also have all relevant detectors )so what do you guys know about the Bosch 2.5 gallon electric water heater? I wanna go fairly simple and inexpensive, I have 400 watts of solar and a 230 ah top of the line lithium battery (and room for more )and victron components , so what do know, thanks much

 

[llamalander]

Propane is very energy dense, so it works well for on demand heaters, if you have propane handy it will work well and quickly.
The Bosch is 1500 watts of 120v. AC, so you need an inverter to deliver that--the lithium will likely handle that output, but that's 125a of 12v. DC, so you should check what the C-value (max recommended charge/discharge rate) for your batteries is.
Another option is a "calorifier," an insulated tank with an electric element, which can draw from your solar/battery more slowly to heat a small volume to 180º or so, which you can mix-down to a comfortable temp with more cold water, probably a 25% increase over the volume of the heater. A 2-5 gallon calorifier will be plenty for a few showers with a low-flow head and the set-up doesn't require huge cables/inverters/battery banks. These are sold as marine heaters, usually designed to use engine heat, but able to use 12/120/240v electricity alone as well.

 

[Peter_n_Margaret]

I suggest that you have insufficient solar/batteries to heat shower water reliably.
Using engine surplus heat would work whilst driving or maybe electrical energy from a larger alternator, whilst driving could be OK.
Cheers,
Peter
OKA196 motorhome

 

[carterd]

A small 12v, well insulated, hot water heater may be an easier option.

12 Volt Water Boiler for Vans and Campers by EX-UP

Our 12V-6 Liter water boiler is designed to fit in motor homes, vehicles, boats (sail and power) with a standard 12 volt hook up and adjustable thermostatic control from approx. 30 ° C to 75 °C. It's equipped with overheating protection, anti-backflow (water), and electricity leakage protection...

expeditionupfitter.com

 

[andy_b]

I have that exact Bosch heater. I have 800w of solar and 600ah of lithium storage. I usually turn the heater on at home while still connected to shore power. Once hot, it doesn’t cycle that much to keep things hot. Similar to the idea of the increased efficiency of a calorifier, I have a mixing valve installed and turned the heater to max output - no idea how much of an impact it makes since we’ve never not had the valve in the system.

More important, I think that @llamalander's point regarding the max output of your battery’s BMS is important to know; mine is 200A which allows me to run both the heater and minisplit at the same time. Likewise, as @Peter_n_Margaret points out, your solar/battery system may be undersized, depending upon how you’re using the camper.

 

[Roktman]

Hey thanks for the replies guys , I’m kinda thinking going with the Bosch 2.5 gal, just turning it on high for 10 or 15 minutes once a day for a warm water shower at the end of the day wouldwork well for us I hear it’s pretty insulated, it might be less finicky than the on-demand system, that X – up water boiler sounds interesting. I’ll keep that cataloged for another time.

 

[llamalander]

Wishing it will work with your existing electrical (then buying an inverter the system can't supply), won't get you a hot shower necessarily. Check the "C"-value of your battery and the max output of the BMS... and do the math. A borderline setup will seriously cut down the lifespan of the batteries, and--of course--"burn your Jeep to the ground"
(required disclaimer for internet electrical)

 

[klahanie]

I have that exact Bosch heater.

Hey Andy, does that need an expansion tank in the water system ? or does the relief valve weep ?

I was looking at that model but the fact that it is for residential gave me pause. Do you have any concerns about using it in a mobile application ?

 

[Victorian]

Here is another boiler option that allows you to use 110V, hot air from your diesel heater, hydronic heat. https://expeditionupfitter.com/coll...0-combiboil-with-comfort-boiler-control-panel

 

[andy_b]

Hey Andy, does that need an expansion tank in the water system ? or does the relief valve weep ?

I was looking at that model but the fact that it is for residential gave me pause. Do you have any concerns about using it in a mobile application ?

No expansion tank; the relief valve hasn’t relieved itself.

I have no specific concerns in a mobile application - could you share what yours might be? The lack of an expansion tank is an issue but space was limited; technically, the install manual made it a recommendation and so I ran with that lol.

 

[andy_b]

Yes, the install manual, I forgot to look into that

Concerns would be standing up to vibration - I once talked to a ferry crew worker who said his (primary ?) job was to walk around with a large insulated screwdriver and to check and tighten wire connections. (not apples to apples I know)

So electrical and water connections, welds etc. Also have seen a few tanks without the shrouding (case), wonder if that might be useful for inspection. It is a pressure tank so that should be good.

Not losing any sleep over it but obviously a failure could potentially be messy. Had I thought to have the space in the wet room (with a floor drain) to locate a HW tank I'd be Iess concerned.

Agreed - I imagined the relief valve venting and being very annoyed - luckily it would mostly be cosmetic. The only electrical in that space is for the heater itself.

I did think about removing the shrouding but it actually made it easier to mount so I left it on.

I agree with the idea that using domestic equipment in a mobile application opens itself to unpredictable problems - that’s one of the reasons I stayed away from a residential minisplit (although I have no factual basis for my confidence in the unit I have apart from its marketing). I had similar concerns using this domestic hot water heater but it is a fairly simple device. All of the electrical connections were made using techniques from ABYC or similar. Basically, crimped/solder connections vs straight soldering, etc. I used a lot of lever nuts in dry areas - I’m not sure that these are approved by ABYC but they tend to be in easy to find or non-critical areas.

For the water fittings, I used SharkBite wherever possible - they are the only connections I have that have never leaked. I also wrapped the SharkBite fittings in their below grade tape; this stuff is similar to self-amalgamating tape that most of us probably have in a toolkit. The big difference is it is clear. Anyhow, no leaks as far as I can see.

 

[andy_b]

Here is another boiler option that allows you to use 110V, hot air from your diesel heater, hydronic heat. https://expeditionupfitter.com/coll...0-combiboil-with-comfort-boiler-control-panel

That seems like a great solution but I would be reluctant based on my own experience with my Planar/Autoterm 2D. It has never worked right and the support from Planar/Autoterm North American (not Expedition Upfitters) has been terrible.

IMHO, the main benefit of using Planar/Autoterm was its cost advantage compared to the “name brands” and a higher perceived quality and post-purchase support compared to Amazon variants. My actual experience is that Planar/Autoterm has gotten more expensive just like everything else and as a consequence, its value has diminished when compared to name brands. Personally, I’d go super cheap and buy a lot of spares or go name brand and not have to deal with the hassles.

 

[Victorian]

That seems like a great solution but I would be reluctant based on my own experience with my Planar/Autoterm 2D. It has never worked right and the support from Planar/Autoterm North American (not Expedition Upfitters) has been terrible.

IMHO, the main benefit of using Planar/Autoterm was its cost advantage compared to the “name brands” and a higher perceived quality and post-purchase support compared to Amazon variants. My actual experience is that Planar/Autoterm has gotten more expensive just like everything else and as a consequence, its value has diminished when compared to name brands. Personally, I’d go super cheap and buy a lot of spares or go name brand and not have to deal with the hassles.

Oh no! Sorry to hear that. Is there anything I can do to help you? We sell tons of the Autoterm 2D and 4D diesel heaters and to be honest, we rarely have customers reaching out for trouble shooting. That of course doesn't mean that they are perfect or the gold standard within the diesel heater market.
In any case, let me know if there is anything I can do for you.

 

[Rebuilder]

I've installed a few of the Bosch 4 gallon water heaters in vans and they work fine with 200ah batteries (Battleborn in my case), 400 watts solar and a 2000w inverter. Something to consider is they don't have a drain so if you need to winterize it you'll need to remove it to empty it or clear it out with compressed air.

 

[Roktman]

Wishing it will work with your existing electrical (then buying an inverter the system can't supply), won't get you a hot shower necessarily. Check the "C"-value of your battery and the max output of the BMS... and do the math. A borderline setup will seriously cut down the lifespan of the batteries, and--of course--"burn your Jeep to the ground"
(required disclaimer for internet electrical)

Hey LLamalander, ??? Bosch unit 1500 watts , 10 to 15 minutes to heat water then shut off , 400 watts solar, 230 ah lithium battery ,2000 watt inverter ????? I don’t have a jeep , lol