In the spring as we were finishing up the truck, we had some specific dates that we wanted to hit for starting our summer travels. The prime window of travel in the far north is pretty narrow, and we wanted to make sure we got there as soon as some of the river crossings opened. As our departure time approached, we had made it pretty much through our entire truck to-do list, but we decided to defer installing the hot water heater until we got back. Surprising as it might seem, we did the whole 5 month trip without a hot water heater and really didn’t miss it. We found that because we stored our water inside the habitat that it was always in the 70-75 degree F range which was quite comfortable for washing hands, face, and dishes. For showering, we would heat a specific amount of water in a kettle on our alcohol stove. We had a digital thermometer and we would heat the water to 107 degrees F. It actually worked perfectly; the water temperature was great and it really helped us ration water as we knew exactly how much we were showering with.
Now that we are back, we are finishing the hot water installation. There is a large area for the hot water heater reserved underneath the forward dinette bench behind the shower wall. From the beginning, we only planned to plumb hot water to the shower as the kitchen seemed fine with room temperature water.
Originally, we planned on installing a sailboat calorifier that would take hot coolant water from the engine and circulate it through a heat exchanger in the calorifier’s insulated tank. We liked that it would heat the water while we were driving using waste heat and that we could use our engine pre-heater to heat the water when not driving. Some of the downsides to the calorifier option is that the calorifier that we have is really larger than we would ever need; it is 5.8 gallons. Also, it has some system complexity by tying the engine coolant system to the habitat hot water system.
On the trip we were really pleased with how our solar and lithium battery combination performed. Even when the weather was cloudy for several days in a row, we used a lot of power extensively in the evening, and we had the truck in a dark ferry hold, the lowest we ever got the batteries was 88% charge state. This lead us to start thinking about using some of the battery and solar capacity to run an electric hot water heater. There are several nice, small 12-volt electric hot water heaters available now. Even at full power they only draw 200-300 watts, so with full sun on our 600 watt solar array, they wouldn’t even put a dent in the battery capacity. They are smaller, though, at only 1.5-1.6 gallons, but in a way that is nice because it would heat quickly.
So we are in comparison mode and looking at the pros and cons of the systems. Both would be great for different reasons.