Originally Posted by Dcomf
The main idea was borrowed from here:
Most of it is outlined there and they show the exchanger mounted in different vehicles. I made my own heat exchanger from 3" copper pipe and copper refrigerator coil much like the heaton exchanger. If you build your own they show the internals of their exchanger to give you an idea how it's done. It is mounted and plumbed into your coolant lines going to the heater core. It is efficient enough that there is usually no need for a second pass through to get water at shower temp. The pump is a small Flojet 1.1 gpm RV pump with a shutoff of 35psi that feeds into the exchanger. Pump was around $35. Use simple garden hose for gazinta and gozoutta water lines and find a place to mount everything.
Here’s an idea that anyone can use. That is, if you don’t have an automatic transmission.
About 10 years ago, I replaced my radiator in my ’86 CJ-7 from a 2 core to a 3 core. The radiator is the same for an auto or standard tranny.
As I was installing the radiator, I noticed on the bottom of it were the attachments for the auto tranny cooler. Since I had a standard, the fittings were capped off.
So I took off the caps and fitted one with a brass quick connect for the output and the other I connected a low flow RV water pump. I put the quick connect before the pump for the input. When I tried the pump on the output side, the heat tended to make the pump stop working properly. You can experiment with that and let me know.
I also used a low flow shower head. It won’t have the pressure you’re used to at home, but keeping the flow slow helped the water get warm. I put in a valve on the output side to control the temp. The faster the water came out, the cooler it was. So, it was a simple but effective temp control.
So, with a water source and the engine running, it wasn’t a bad little shower.