Friday, August 16, 2013


Mounted RV pump below "On Demand LP Water Heater

The self constructed Portable Hot Water Heater shown in this article produces portable pressurized hot water.  It uses all easily obtainable parts.  Great for use when camping, or in situations which local food handling codes require hot water for washing hands, etc.

After years of all types of camping, Dutch Oven Cooking functions, and other such events, I tired of the variety of ways we always attempted to make Hot Water.  I have tent camped, as well as owning a 32ft Luxury Class A motor home.   Regardless of the type, I have always cooked outside at the picnic table.  Rain or shine, it didn't matter.  But having hot dish water when preparing food, and the eventual clean-up has always been an issue.  Pots on a camp stove either take too long, were in the way, or inconvenient to dispense the hot water when your hands are dirty or covered with raw food.

Later modification.  Not shown in this original article I added a foot switch to control the pump to make the sink application hands free.  This could be altered further for a bypass to either use the foot switch or not.  The foot switch was a tool foot controller purchased at Harbor Freight for under $30.  It was to control 110V AC.  It was easy to modify and wire into my 12V DC wiring in the circuit just before the RV pump. 

I have several friends that have a commercially built table top unit that runs off batteries and small LP canisters.  I saw them struggle with their heater when they failed to heat or pump.  Many parts seem to be something special made for those units.  Not readily available for those times you are on the road and the unit fails.

So I also wanted a unit that would be easy to find parts for.

I also trimmed off part of the hand truck.  The bottom lifting platform was shortened considerably.  I had a confined space I wanted to fit this in during transport and storage.  You may be able to skip this step if size is not a factor.

Should you attempt to build one similar to the one shown here.  You will need access to an electric or gas welder, have things like a drill, hack saw, etc.  You assume all risk. You will also have to have some general plumbing and electrical wiring knowledge. 

A really high water flow through this unit will not produce really high temp water.  The heater does not have that BTU capacity.  At a medium flow it will scald your hands.  We have used the output hooked to a longer hose and used it to take very warm showers for as long as you have water to supply it.

After much research I found this instant on demand water heater sold at Camping World for around $130.  They are available on the internet also.

I combined this with a standard RV 12V on demand water pump.  This makes the unit work even it you have no pressurized water source. These pumps can also be found at Camping World and many other places.  Prices range from $50 to around $150.  I bought one for about $70. 

My only other major component was a  2 wheeled hand truck/dolly.  I found a new one at Harbor Freight for around $30.  Had I looked around I am sure I could have picked one up at a garage sale for around $5.

Most of the remaining plumbing and electrical parts I had laying around from doing remodeling jobs as side work the past couple of years.  I used mostly brass fitting to makes things last longer.  I am sure you could adapt the idea to plastic fittings.  I also already had a blue plastic Reliance brand water storage container I used for camping.  Since I knew these are easy to come by for replacements, I designed around that as well.

My 12V power source (to run the water pump) would be a portable Schumacher XP2260  Jump Start unit.  The Jump Start unit had a cigarette lighter style connector…so that is what I wired my RV Pump wire with.  As a back-up this plug allows me to also plug directly into my vehicle.  I already had the charging unit so there was no added expense..  After testing I found it was more than adequate.

The On Demand LP Hot Water Heater is powered off a 5gal Propane tank which I also had.  It also uses a D battery to power the automatic electronic igniter.

I did end up purchasing a Laundry style combo hot and cold water faucet.  Without a lot of technical detail I will let the photos speak for themselves.  The plumbing is split and provides hot and cold water. 

Later I found it convenient to add a T in the water line, with a valve, so I could drain the Water Heater coils for storage.  This avoids unnecessary work to loosen and remove a hose connection each time I needed to drain the tank for storage. Heavy duty braided burst proof hoses were used where ever possible.

I also created a siphon tube that reached to the bottom of the blue water storage tank.  That was kind of tricky.  I found this kind of restricted the water flow.  But necessary if your water tank is sitting on the ground. 

I found it easier, and creates more pressure,  to just thread a hose bib valve into the cap of the blue water storage tank and set it up on the picnic table.  But that might not always be an option.

With the tank higher than the RV pump on the assembly, the water gravity feeds down to the pump.  No siphon tube is required if you can raise the water source.  

My configuration also allows for a pressurized water source to be connected.  City or campground pressurized water you can connect up to with a hose.

At a later date we added a foot switch.  With this in the circuit, the switch basically opens or closes the power source.  This is especially handy when working with food.  The faucet valves can be left open.  In the normal position the foot switch has the power circuit in an "open" state.  No voltage.  Press the foot switch and the contacts "close" and apply power to the pump which in turn kicks on and water flows.  No need to touch the faucet with chicken juice on your hands. 

For the switch, a power tool ON/OFF foot switch was used.  Found at Harbor Freight for about $30 (Don't buy the variable speed type)  With some minor electrical skills you should be able modify and wire this in, to OPEN or CLOSE the Positive 12V DC between the voltage source and the RV Pump.

A simple toggle switch can be added to "bypass" the foot switch when normal sink valve operation is desired. 

A basic diagram is below with a rough parts list and estimated cost.  The better the scrounger you are the cheaper it will be.  Go compare one of the commercially built camping hot water heaters.  They run $300 or more.  This is comparable if you scrounge parts.....and way more functional.

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