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  1. #1
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    Default DIY Water Distilling

    Motivation

    This thread is an adjunct of the Running cooler with more power using WMI thread. See Running cooler with more power using WMI: https://www.4x4community.co.za/forum...36#post4621036

    One could use tap water in their Water-Methanol Injection (WMI) mix, but you must be prepared to annually remove and soak with a calcium removing formula such as CLR® or vinegar. I prefer using distilled water as Cape Town water is high in calcium carbonate.

    Buying distilled water increases the cost of WMI and the purchased plastic bottles add to the environmental problem. One can buy an active / commercial distiller for DIY, but these can be expensive to purchase and are power hungry. There are some vague references to passive solar distillers on the web. The following is a much more complete, local build passive solar distiller using local materials (my design).

    Materials
    one sheet of exterior grade plywood, minimum 12mm thickness
    waterproof, UV resistant, caulk x 2 tubes (minimum)
    black paint
    assortment of pipes for sawing to length and in half along the length – stiff, but not brittle, larger diameter is better
    sheet of plate glass – 1270 x width (outside of frame to outside)
    brass screws (just short of double the plywood thickness)
    black plastic sheeting
    contact glue
    roll of weather stripping (width to match thickness of plywood; to provide a seal between the glass and frame)

    Tools
    saw (wood, circular saw and jigsaw or band / scroll saw)
    pencil or caulk line with dispenser
    screw driver (head to match screw heads)
    caulk gun, see pic
    Attached Images Attached Images  
    Last edited by Butch Dassie; 2021/04/14 at 08:51 PM.
    Renault Duster 4WD Gen1: No Meow, GC = 254mm, WD = 820mm

  2. #2
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    Default Re: DIY Water Distilling

    The basic idea is to point a pane of glass (90 degrees) at the sun with black channels underneath full of water (the softer the better, ex. rainwater). However, the sun moves across the sky at different angles during the seasons. Cape Town is a further 10 degrees south of the Tropic of Capricorn. So, at the winter solstice to point perpendicular to the sun, you would need to aim your still at 32.5 degrees. However, at the summer solstice, this angle would need to be 79.5 degrees. In-between at 56 degrees is the equinox, which the sun passes through twice a year. Thus, getting as close to your local equinox is optimal.
    Attached Images Attached Images  
    Renault Duster 4WD Gen1: No Meow, GC = 254mm, WD = 820mm

  3. #3
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    Default Re: DIY Water Distilling

    The front of each half pipe is slightly lower than the back side to allow filling from the top, which overflows to the rain gutter / half pipes below. However, there is a gap between the bottom half pipe and glass evaporator to allow any excess un-distilled water to escape and not contaminate the distilled water.
    Attached Images Attached Images  
    Renault Duster 4WD Gen1: No Meow, GC = 254mm, WD = 820mm

  4. #4
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    Default Re: DIY Water Distilling

    The bottom of the glass sits in a ¾ lengthwise cut pipe. The outside top side is caulked, but the inside gap allows the condensation to drip into the ¾ cut pipe. A collector pipe is connected to one side of the ¾ cut pipe leading downhill to a collector bottle.
    Attached Images Attached Images  
    Renault Duster 4WD Gen1: No Meow, GC = 254mm, WD = 820mm

  5. #5
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    Default Re: DIY Water Distilling

    This is the pattern that I used. I didn't quite match the 56 degrees, but 54 degrees allowed better use of the available plywood dimensions. Note the back and front state maximum width of 83.34. You can make yours narrower, like I did. What I did was to look at my pipe rack. I was looking for the optimal pipe length or multiple thereof to best use all of my leftover pipes. For me, this was 54 cm. So, if yours is 83.34 cm wide, you'll be able to generate more distilled water that I will. I'm hoping for two litres per day in summer and one litre in winter.

    Assembly Method 1 – drill and screw pre-cut pipes to the middle support

    Assembly Method 2 – assemble all wood components and then cut the pipe as the centre may bulge. Cutting the pipe lengths after the wood components are assembled makes a lot of sense and saves some caulk where the wood bulges out slightly.

    Assembly Method 3

    Marking the support for cutting away where the half pipes will lie requires some thought. If you progress from the bottom with the largest pipe towards the smallest pipe at the top, each change in pipe size will require a set-back from the glass. It might be best to mix the pipe sizes to prevent from getting too far back. However, you do want the water placed at the top to cascade down when over-filled like the champagne tower.
    Attached Images Attached Images  
    Renault Duster 4WD Gen1: No Meow, GC = 254mm, WD = 820mm

  6. #6
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    Default Re: DIY Water Distilling

    Thus, you need to tilt the front of the half pipe to be lower than the back. You can place a straight edge along the top (open “C”) and measure both sides to the base of the support wherein the shortest to the base will be at the front of the still. When you change pipe size, measure the perpendicular distance from the front edge of the pipe to the front slope where the glass would have set. Draw a parallel line up at this distance. When setting the next same sized pipe above the new size of pipe, note the distance between where the two fronts touch the line. The next pipe above should be at the same distance above the one lower. This helps ensure all pipes are tilted the same, but also greatly helps with the aesthetics.

    Offsets back to larger sized pipe
    pic one

    Still
    cut plywood
    pic two
    pipes ready to halve
    pic three
    half cut pipes
    pic four
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    Renault Duster 4WD Gen1: No Meow, GC = 254mm, WD = 820mm

  7. #7
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    Default Re: DIY Water Distilling

    Gutter at bottom, longer one to carry glass plate
    pic one
    showing internal supports don't allow overflow to enter the distilled pipe
    pics two to four
    Now with experience, the larger pipes are easier to set-up closer to the glass front and higher up the support (more pipes), but are more difficult to caulk and paint underneath. The flexible pipes should be avoided as they twisted and bent at different angles. Really brittle plastic pipes should also be avoided.
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    Renault Duster 4WD Gen1: No Meow, GC = 254mm, WD = 820mm

  8. #8
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    Default Re: DIY Water Distilling

    The most difficult part will be the sealing for water leaks. I had a roll of vinyl laying about and used some to seal the back of the pipes so that there weren't any gaps between the pipes. This would catch any spilt water and channel it to a lower pipe.
    pic one
    I had some leftover black Plascon Velvaglo paint (ha – I still have some leftover Velvaglo).
    pic two
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    Renault Duster 4WD Gen1: No Meow, GC = 254mm, WD = 820mm

  9. #9
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    Default Re: DIY Water Distilling

    Next project will be to add a float valve to automatically fill the upper pipe. For now, I transfer buckets of harvested rain water.

    Maintenance

    Besides ensuring the integrity of the caulked joins and black paint, you'll need to clean the exterior glass surface, especially after a howling South-Easter. Also check for and remove algal growth on the black pipes.
    Renault Duster 4WD Gen1: No Meow, GC = 254mm, WD = 820mm

  10. #10
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    Default Re: DIY Water Distilling

    I found that the gap between the collecting pipe at the bottom holding the glass and the last half pipe, which allows any overfilling with rain water in the above half pipes to escape, was allowing cold air to enter the bottom chilling the lower glass area. Thus, the lower glass area was not as efficient in evaporating the water in the lower half pipes. I stuffed old rags up to the height of the lowest half pipe, but below the slit between glass and collecting pipe. This stopped the cold air from entering while still allowing an overflow to not enter the distilled water area.

    I also applied foam strips on the side of the still where the glass plate touches just to seal any very warm air leaks. Now the full glass plate is covered with condensation generating one and a half litres of distilled water a day in late winter / early spring.
    Renault Duster 4WD Gen1: No Meow, GC = 254mm, WD = 820mm

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