I know of two models that use use the hot engine coolant to heat water (heat exchanger). Helton and Twine. I chose the Helton Hot Water Kit because the all the hose inputs and outputs are on the same side.
The goal was to have a shower where the water heater, water pump and water were all on board the vehicle. I wanted to use the system without opening the hood.
The hardest part of the install was finding a place for mounting the heat exchanger in the engine compartment that allowed convenient connection to the existing heater hoses. I finally found a great spot under the relocated window washer bottle (relocated with Slee Kit). The heat exchanger is the red device. Bolted to the inner fender:
Heater hoses and fresh water hoses routed. Connected directly to the heater valve, the flow of the coolant can be adjusted from the heater controls on the dashboard. I found about 3/4 into the red on the heater control was perfect:
The water containers are in the rear of the truck so the electric fresh water pump (Jabsco Variable Speed Water Pump) mounted under the shelf in rear cargo area (drivers side). A hole was cut in the floor to route the tube that goes to the front of the truck:
The first flow of hot water can be scalding since it's been sitting in the exchanger so I included a cold / hot water mixer anti-scald device. This also allows more control of the warm water temperature. This is plumbed like at your home, both hot and cold water flows to the valve and can be adjusted. In addition, a valve at the top to control the flow. Opened about 1/4 of the way allowed for a good shower while reducing the water usage:
Here is the system setup last month in Arizona next to Canyon de Chelley:
The input hose to the electric water pump in one of the 5 gallon water containers:
This system makes it very easy to take a shower. Just drive into camp. Put input tube into fresh water. Setup shower tent (with AstroTurf for the floor). Connect shower hose. Run engine at 1000 RPM. Enjoy hot shower
I ordered many of the plumbing parts from West Marine. Some of the needed parts:
3 Barbed Hose Reducer, 3/8" to 1/2" Part: SEAFIT 139952 - Helton uses 3/8" connectors. Needed to adapt to 1/2"
1 Barbed Nylon Hose Tee, 1/2" Part: SEAFIT 139960 - To allow cold water to mixer
Series 162 PVC Tubing, 3/8"ID Part: SHIELDS RUBBER 116-162-0386 - Water To / From Helton heat exchanger
Series 162 PVC Tubing, 1/2"ID Part: SHIELDS RUBBER 116-162-0126 - All water line to / from electric water pump
Brass Male Pipe Thread to Hose NPT 1/2 - For mixer, anti scald device connection to tubing
Brass Female Pipe Thread to Hose NPT 1/2 - For mixer, anti scald device connection to tubing
A few issues:
1. I need to add a valve to completely drain the system. If water freezes in the heat exchanger, it could cause it to crack and create a leak in the engine cooling system.
2. The tubing that was attached to the shower sprayer was not strong enough to withstand the pressure from the electric water pump. I replaced it with with 3/8" tubing from West Marine.
3. The standard hose clamps on the fresh water system under the hood, appear to loosen with the cycle of heating then cooling which causes very small leaks. Re-tightening fixes it, but I need a permanent solution.
4. I need some type of quick connect for the shower hose to the truck.
5. Need to install manual throttle.
