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Get tanked! Keep hot water flowing on your homestead.

It was intrigued by Tim King's article (March/April 2011, pp 50-51) on winter water heating. We use a similar system in our home here in Vermont. We also have a Waterford Stanley cookstove which we use to heat our house and water in the winter. I originally plumbed it to be used as a preheater for the gas water heater, but I have since disconnected the water heater entirely, and the woodstove provides my family of four with all our domestic hot water during the winter. During the summer, we heat the water with solar collectors, but more on that later.

Mr. King's excellent article is under the heading "Alternative Energy." I'd like to make a point that's been made many times before, but bears repeating--the best alternative energy source is the energy you don't need to use. The extensive insulation and weather sealing we have done to our 100+ year-old 1,200 sq. ft. home allows us to heat it with about two to three cords of firewood per year, and I'm picking away at making it more efficient. The winter before we bought this house, the previous owners used 1,500 gallons of heating oil. The insulation paid for itself in one year. One of the first things I did was to remove the boiler and oil tank, and convert that comer of the basement into my office. Splitting and stacking two cords of firewood per year amounts to a hobby. I hope to live long enough that it isn't easy anymore (given the alternative), and I'm trying to set up a house that can take care of its occupants with minimal inputs.

I'm sorry that Mr. King lost his original water jacket (what Waterford calls the stainless steel box for water heating), especially because to replace it now costs about $250. For anyone else with a Stanley thinking about this, the water jacket does not actually shorten the firebox, as Mr. King thought: the heat shield at the back of the firebox is removed to install the tank (after all, you hardly need a heat shield when there's water between the fire and the back wall) and the water jacket's thickness is the same as the removed heat shield's.


I noticed that Tim's preheater tank is located quite high off the floor. While it is necessary for the hot water to rise continuously into the tank for the thermosiphon to work, it is possible to have the bottom of a tall tank near the floor, making it easier to position the tank, which can get pretty heavy. Ours is 105 gallons, so in addition to the 60 lbs. or so of empty tank, the water in it weighs about 875 lbs.


In Fig. 1, you can see that my tank sits on a two-inch insulated platform (the root cellar is under it, and I don't want the bottom of the tank chilled, or the potatoes warmed). The cold water inlet is near the bottom of the tank, and the cold water supply for the thermosiphon is connected with that inlet. The hot water from the woodstove enters the tank about 2/3 up the height of the tank. This is not maximally effective thermodynamically, but we already make more hot water than my family can use, and I have other reasons, irrelevant here, why I don't want to plumb it to the top of the tank.

In photo 1, you can see the lower (cold) and upper (hot) pipes of the thermosiphon loop. I kept the slope of the hot side pretty low: I use it as a rapid-drying laundry rod. The cold supply is sloped downwards toward the stove, but this is for draining the system easily--it is not necessary for the thermosiphon.


In photo 2, you see the hookup on the back of the stove. I use a lot of unions. I have cut into my own and other people's plumbing to fix it too many times to count--unions cost a few bucks, but the labor they save in the long run is worth it. The fitting sticking out of the brass T fitting is a temperature-pressure relief valve. If the water in the jacket starts to boil, the water is shunted through the vertical pipe to a floor drain. Without it, possible scenarios include the plumbing exploding--I strongly recommend a T-P valve here. Also note the drain in the elbow at the lowest point in the system. I felt very clever remembering to put it in, but if I had it to do again, I'd build a proper drain with a reducer T and a small 1/4 turn valve.


Photo 3 shows the other side of the wall (yes, more unions). If I want to drain the loop, ! turn off this valve (and the valve on the cold side that you can't see), open the elbow drain, and open the waste drain on the lower side of this valve. This allows air to run into the pipe so all the water drains out the elbow. The loop plus the jacket almost fills a one-gallon bucket. You can also see the tempering valve on the hot water line coming out of the tank. It's important not to try to wash your hands in 170[degrees]F water.

Photo 4 shows what makes our hot water when it's not woodstove season. The roof pitch the panels are on is only 4/12. Usually domestic hot water panels are pitched much higher, but there are two reasons for this pitch. First, because of the woodstove loop, we only want solar heat in the summer, when the sun is high. The other is that we have pretty strong winds out of the north from time to time, and I really didn't want my solar panels to be one of the things I find in the south yard after a storm, so I kept them down close to the roof. The stovepipe you see next to the collectors comes from the Stanley. The heating functions are thereby stacked: plumbing runs are kept short reducing cost, but also reducing friction, thereby increasing system efficiency. This system wasn't cheap (partly because I spec'ed a larger-than-normal tank), but it's a design proven over decades of use in northern Europe, and allows me to have year-round hot water without fossil fuel inputs.


The gas water heater has been long disconnected, and there isn't even a propane tank on the premises anymore.

The combination of these two systems provides my family with all of our domestic hot water, and I am in the process of plumbing a baseboard heater in our guest room as a heat dump for the extra hot water the system makes in the cold weather. The Stanley provides all the heat for our 1,200 sq. ft. house, so it is pretty much fired up all winter long.

Finally, the exchange rates have changed dramatically since we bought our Stanley, and it's expensive enough that I wouldn't buy it now. There are other options available--just make sure you can install a water jacket.


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Title Annotation:Alternative energy
Author:Wood, Ned
Publication:Countryside & Small Stock Journal
Geographic Code:1USA
Date:Jul 1, 2011
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