air driven auto top-off. construction and tweaking log

[kwirky]

Originally Posted by Railskinner

just curious at to the set up u have for a air driven top up. would be gr8 to see some pictures as well fo your set up. I'm in the mids of getting a top up system going. getting tired of the daily water /jug 1 gallon . top up

It'd be hard to get pictures, since it's under the tank now, and quite crammed to get a good picture, but it's very simple to explain.

You have a large jug, glass would be better, but plastic would do. I used one of these:


they're available at ukranian tire for $10. a glass bottle would be better, and I'll explain why in a bit.

I cut the air plug off, and crammed the same tubing used in RO/DI setups. I then cut a hole JUST snug enough to cram another tube in. One tube goes to the bottom, and that's where the water comes out. The other tube just goes in a bit, and that's where the air goes in.
The existing hole on the jug is the right size for the tubing. the hole I drilled I had to ensure was air tight. I was too lazy to go a step further and seal the holes with any kind of silicone or anything. It worked as is.

I unscrewed the cap where the faucet is, and unscrewed the faucet, then wrapped the faucet's threading in teflon tape to further make the jug air tight. The jug must be as air tight as possible for it to work.

Fill with water, recap. I filled it with kalkwasser mix, since there's no pump the kalkwasser is running through to clog. Even better than a peristalic pump

Then you attach an air pump to the air inlet (the pipe that only goes in a bit), and the pipe that reaches the bottom goes to the sump. ****You MUST have a check valve on the pump, especially if it's a plastic jug, since when the pump stops, the pressure WILL cause the water to go up the airline and into the pump if you don't have a checkvalve**** The water output going to the sump must not end up at a level below the water line inside the jug, or else you'll have a siphon happen, and the jug will just be emptied when the air pump stops.

Plug in your air pump to see the wate rise up the output tube, then slowly trickle out of the tubing. Cut the power to the air pump, and you'll see it stop in about 30 seconds. I run it with a little air pump rated for a 5 gallon aquarium. It pumps 1.8 gallons in 10 minutes. You can test your own setup to see how fast it pumps the water.

You can run it on a timer, and tweak your timings according to when you want it topped off, and how much. Or use a float switch, or both for added backup.

about the glass bottle:
the plastic bottle expands and contracts according to the air pressure, causing a delay in the start/stop of the system. A glass bottle wouldn't do this, giving immediate response to the starting/stopping of the system, making a float switch even more attractive.