A couple years ago I designed and built an underhood shower for my 2nd gen 4runner. 5 years later its still working great and I thought others might be interested in how I did it.

The under hood shower works by utilizing waste heat produced by your engine to heat the shower water. The figure below has a good graphical representation of your engine’s cooling system and is based on a figure borrowed from the HowStuffWorks.com website. As shown in the figure, your engine already uses the hot radiator fluid to heat the passenger compartment. A small amount of coolant is bleed from the top of the engine, and when you turn your heater on, the heater valve (J in the figure below) opens and allows the fluid to flow through the heater core which is mounted in your dash. A fan blows air over the heater core and this hot air is what heats the passenger compartment.
It turns out that you can also use the engine coolant to heat your shower water by placing a heat exchanger in series with the heater core. The figure below shows how your vehicles existing cooling system can be used to make hot water. The engine coolant normally bleed from the top of the engine, now passes through the heat exchanger before making its way to the heater core. A 12V water pump is used to draw water from any source, pump it through the heat exchanger and out the shower head. Temperature control is achieved with engine RPM.
This system in no way affects the normal usage of your heater, unless maybe you were trying to run your heater and take a shower at the same time. In this case you probably would not get much hot air out of the heater since the radiator fluid leaving the shower heat exchanger is not very hot. When you are not using the shower, your heater will function normally since the shower heat exchanger will not be cooling the radiator fluid.

System Overview:


Design of homebuilt shell and tube heat exchanger:


Heat exchanger installed behind passenger quarter panel:


Shower set up for use:


There is much more detailed information in the attachments on my website here: http://sites.google.com/site/wastedf...ta/camp-shower

 

thats pretty slick, but im a roughneck and would never take a shower in the desert.. plus most of my wheeling trips are only a couple days so..

 

Your filter should be before your heat exchanger so you don't clog the exchanger.

You have a split before the heat exchanger and plumb it so you can adjust the temperature of the water (more hot water or more cold water from the source).
If you run the hose to the back of the truck, you could hang a loop with a curtain from your roof rack so you can have privacy while you shower.

Cool idea none the less, wicked that you actually built one.

 

So it pulls from any water source?

The creeks I'm usually around when camping are pretty green so I probably wouldn't ever use it.

But if you put a filtration system on that puppy... My girlfriend would probably love it!

 

Thats pretty neat.
And having been camping out on the dunes without a shower, i can tell you that this would be awesome.
Imagine helmet hair for 3 days :/ yuck.

 

Awesome! Great idea and great write-up, good job!

I will definitely remember this

 

Very cool.
I thought about installing one of these on my past rigs, but never got around to it.

http://www.hotcampshowers.com/vehicle_mounted_shower

 

I've had one of the R&M heat exhangers installed on my '85 for years now, very nice:
- http://www.4crawler.com/4x4/CheapTricks/Shower.shtml

Old photo of the exchanger tube under the fender:


A few years ago I hard mounted the water pump behind my front bumper and wired it to a switch under the hood. Now only takes two quick connect hoses to hook it up. I also have a valve under the hood to adjust the coolant flow into the exchanger to adjust water temps.

 

im a plumber and im gonna build one with my own disign, but im gonna put 2 quick connects under the hood and make a portable tank with a coil to heat the inside and would hold 15 gallons or so of hot water and would be controlled with a thermastat oh snap idea's a flowin

 

its as easy as this (just dont pay attention to the red box) http://www.reliant.com/en_US/Platts/art/EA23_1.gif very good idea though

 

the things we do in the name of inventing for the sake of inventing