Faucet, Pump, or...

[MarcusDS]

I've read a lot here about using direct connection to a faucet for cooling condensers, or using a pump from a sink/bucket. Has anyone tried a Venturi?

There are some commercial venturi fittings available, but all the ones I could find were way too large for this or not made to be used as a pump. As an example, search for Lasco Venturi Tee on the web. From an article (http://randystacye.com/diy_venturi.htm) on aquarium protein skimmers, I saw a homemade venturi using a piece of 3/4 PVC filled with Sani-Tred "Quick Patch", then drilled to form a venturi (step drill bit forms the sloping inner diameter). They drilled both sides and inserted a small tube in the side for suction (for aeration, I believe. See below image, left side). A small modification would make this an efficient venturi pump for use in a bucket or sink. Disclaimer: I didn't make or test this, but the design is used in large scale water removal and dredging. A little PaintShop magic (like Photoshop, but cheaper) and the venturi pump in the right side below is born. Water flow is from left to right in both pictures.

aeration venturi to venturi pump

The original is designed to pull a little air into a large water stream. We need to drop the feed water diameter down enough that you don't use as much tap water, and open up the suction to pull more 'tank' water into the smaller stream. To do this add a fitting to drop the input to 1/4", then fill the 3/4" part with the Quick Patch. Once cured, drill with a straight bit all the way through, using the input fitting as a guide. Pick a bit size that barely fits through the 1/4" fitting. Then use a step drill bit from the other side to create the venturi's sloping walls. Using a drill press, drill at an angle, as indicated, just through to the middle. I've only drawn two holes, but 4 would work better (all at the same place horizontally, offset 90 degrees around the pipe). The angle isn't critical - anything 30-45 degrees from straight in should work fine (Technically, anything from perpendicular over will work, but a little angle increases efficiency. See image for angle direction). For 4 holes, I would try a 5/32" or 3/16" drill bit. 1/8" might be too restrictive. More than 4 holes or larger than 3/16" might weaken the Quick Patch where they overlap in the middle.

The idea is to use a lot less tap water than the direct faucet connection to feed your condenser, saving money and water. Attach the 1/4" side to your tap, the other side to your condenser, and drop the venturi fitting into a half full sink. When water pressure is applied, the fast moving water exiting the 1/4" hole will suck water from the sink through the small side holes and 'pump' it through the condenser. I'm honestly not sure how this will work if you drop the diameter back down to 1/4" after the fitting. The back pressure may kill the venturi effect entirely. Ideally, you'd use a 1/4" pipe to make the venturi, and drill both sides with the slope like the original, but I don't know where you'd find a step drill bit long and thin enough to do the job.

If you do try this, keep an eye on the sink! It won't fill up as fast as an open faucet would, but it will still fill up. If you don't have an overflow hole (many don't these days), you'll need to let water out occasionally. But if it works, you won't need a separate pump, and you save water. Make sure you test ANY venturi before connecting it to your system. A well designed venturi pump can move a surprising amount of water.

[Dnderhead]

cooling a still takes so little water its not necessary or wanted.

[Prairiepiss]

How would you be saving? You would still need to fill the sink from the tap. Then drain the sink when done.

A drum or even a bucket with a electric pump would be better. So you could reuse the water. But I dint think your venturi pump will have the head lift needed to supply many of the stills. The head pressure would be too high. And it would just fill the container.