Friday, February 20, 2009
Day 25 – I get a hot shower (the fastest way to a woman’s heart)
(Depending on how dirty the lady may be).
Living in an off-grid system is sometimes an exercise in evaluating your priorities. Things break. Shit happens. Someone has to have the time, spare parts, and the know-how to fix it. Much like spending a day and a half without power, 10 days without hot water made me appreciate that readily available supply in my apartment in DC. Don’t take that hot water for granted. But do you have to get taken to the cleaners? (har-har)
So, you want to get rid of that energy-gobbling dinosaur of a hot water heater? The tropics allow for different types of solar hot water to be a real possibility. At the Ag Fair Ryan Evans and I got stuck in a very nice used-car salesman-like pitch for a small passive/active solar water-heating unit. We didn’t mention to the gentleman that we already were living with a unit, so we listened politely. Some of the ideas his company is marketing were pretty clever; you can amend your old hot water heater with a new valve to control for in/outflow to the panels on the roof. This is very similar to the system we have on the bathhouse.
This indoor/outdoor setup is the place where we can go to pursue that elusive mistress, the hot shower. There is an insulated storage tank with four input/output pipes. A regular electric water heater has two: cold water in and hot water out. Our tank brings cold water in from our gravity-fed distribution system and then, if the net temperature difference between the water in the tank and the sensor on the roof is greater than a predetermined limit, the colder water is pumped out of the tank and up to the panel. This panel is a passive heater, the water sits in the series of tubes within the panel until it reaches the next predetermined temperature difference (usually about 15 degrees) at which time it is sent back into the tank to stay hot until there is a demand on the system. On a sunny day this system can replenish quickly and the insulated tank can hold quite a bit of water at a decent temperature.
There are other systems utilized on the farm. Dan Glenn uses a completely passive system at his container house on the hill. A passive solar water heater is as simple as a coiled black hose on the roof.
What are the drawbacks to this system? Primary disadvantages are that the length of the hose limits the amount of hot water significantly and the inconvenient times of day that the water is at peak temperature. The sun doesn’t get up early enough for a morning shower and later in the evening the hose isn’t insulated enough to stay warm. However, This system requires Avoiding using complicated technology is a plus because there are no pumps to break and leave us all without hot water for a week.
Marshall Bartlett, one of the other R2R students is designing a third type of hot water system for another house on the farm. I look forward to seeing how that works out. For now, I’ll cope with my cold outdoor shower and appreciate it when I get one hot.