It's really simple. The copper tubing you see sticking out the ends is your clean water intake and output. One end you would hook a garden hose to with hose clamps to an attwood submersible non priming 12v pump. available at RV places. They are pretty cheap. The other copper tube is attached to a shower head or whatever via garden hose. Usually routed back to the firewall and up the hood. Open your hood and its pointing out and at you. The barbs hook inline with your 5/8" heater hose. They are plumbed into the tank which heats the water going through the copper tubing. You can have hot showers until you run out of gas. Some people have put valves inline with the garden hose to regulate flow and therefore adjust the temp but I don't think its necessary.
Here's your parts list:
garden hose, number of feet?
4 5/8" hose clampsattwood pump part no. V1250 submersible bilge pump. No priming necessary. As far as wiring the pump you would need to take a power and ground up to the battery. I've seen people use lamp cords. Simple. Attach to battery with alligator clips.
That's about it.
