Snow capable precipitation collector
I’m sort of gearing up for a complete tinyhouse support system rough design, and I figure maybe I’ll break the subsystems down into separate posts. So this isn’t anything much, but here it is.
Here’s a design for collecting and melting snow for use as clean water. The energy to melt the snow is provided by waste heat from the house, and if needed solar thermal panels. About 5.5 kWh for 60 liters per day of water.
If it rains during winter that could be a problem, that water might be wasted, as the diverter might not function or the pipe could get clogged with slush. So room for improvement there.
You could change the way the tube is done, the reason it connects at the bottom of the box rather than the top is so that relatively little heat is lost, but maybe it would be better to put it so it connects at the top of the tank instead, actually, so no terminations are needed below the waterline inside the tank.
After a snowfall, you open the lid and brush the snow into the box, probably with a pole-like implement kept for the purpose or by going under the tarp and pushing it in. I posted before about the possibility of using water to wash the snow into the tank, and I think that would be fine, but decided to keep the system itself less complex, at the cost of user effort, since you can do the snow brushing into the box at your leisure.
Rainwater diversion is accomplished by taking a bucket, tilting it at an angle, resting on a pivot, and a sort of trough to direct water into it. When the bucket is empty, the trough is under the spout from which the rainwater comes, directing water into the bucket. As it fills up, the bucket tips, removing the trough, so water falls into the tube and thence into the box.
There is an insulated cap under the trough, attached to it, which blocks the pipe when the bucket is in divert mode. That reduces the amount of heat that would be lost in the winter, though you could just switch it twice a year or something.
then there is a small hole in the bucket so the water can drain out over a few hours.
The surface is anything sufficiently strong, and it should be UV resistant, which is a problem. A tarp like this one seems like it might be good. With one side aluminized like that I bet it would last a while, but I couldn’t find any good information on how long a tarp lasts. Greenhouse plastic is fairly cheap but would only last 3-4 years, apparently. Presumably the tarp would quite a bit longer than that then, and it’s a little cheaper too, because it does not need to be able to transmit light, so the light can be blocked right at the surface with the aluminized layer.
Might be better to get one without any flame retardants added, though. That would be a legitimate concern here, especially because any UV degradation that did occur would release such chemicals from the plastic. The usual practice of discarding the first several liters to come off the collection surface helps of course, but I don’t think it would be practical with snow, whether you wash it off the surface with water or not. Activated carbon may remove any harmful substances, but you’d have to check, which might be hard given how mfgrs tend not to share what the tarp contains.
Maybe 1/8 inch plywood would be a reasonable price. 1/4 inch is $14 a sheet, so if it was half that… What else is there that is cheap by the square meter, known to be nontoxic, and UV resistant? Thin aluminum sheet metal might be cheap. The commodity price of aluminum is about $1.2 per pound so if it is half a millimeter thick that would be pretty cheap, I think it has a density of 2.7 or so, so that would be less than 500 grams per sq meter and should only be a few bucks. Can’t find anywhere with it at this price though.
I’m thinking there would be another, smaller one for water that was actually for drinking and cooking, or it could be integrated with this one, with aluminum or another known non-toxic but more expensive material used as the collector surface.
Or maybe you could have the surface automatically roll up when not in use, eliminating the sun exposure so you could just use known non toxic polyethylene sheet….
I wonder if you could use mylar, aluminized side towards the sun so it shades the plastic, and then shape it for as a giant reflector for various purposes.