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Making A Zero Backpressure Check Valve

I have a portion of my bypass water going to the SS heater coil in my woodstove and since it goes high above the rest of the system in order to clear a doorway I ran into some issues. All goes according to plan once I force the water up and over. However if there is a power interruption either by me or the power lines I immediately loose the prime and the coil is emptied and soon overheats and melts the pvc fittings.

So what I needed was a check valve that would not create any back pressure as you all know how precious flow is in AP and I had no idea where to find such a valve in at least 1". I thought about it for a while and came up with a nice simple and cheap solution. It has been working perfectly and next I will install one in the sump pump line as well. So here's the plan. I believe all is explained in the photos but let me know if you need help with it.

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Comment by Irvin Carrero on May 9, 2014 at 4:57pm
Sewer check valves, yep I tried a 2 inch sewage check valve. They work for Glenn's "Aqua zen Burper" airlift. I'd like to see if I could use it for a flat aquaponics roof project down here in PR. Most of our homes are flat concrete roofs.
Comment by Jim Fisk on May 5, 2014 at 7:57am

Thanks Jeremiah! I should remind anyone making this that it pays to mark the direction of flow with an arrow as a reminder before gluing it into the system. Just in case of a DUH moment

Comment by Jeremiah Robinson on May 5, 2014 at 6:58am

A thing of beauty!

Comment by Chris Carr on March 6, 2013 at 6:48am

Sorry Jim, i meant the water inlet portion of an airlift design seen here near the end of the document.

you make a great point about operating position though. A flapper is only going to work well in one position. Thanks for sharing. Really handy!

Comment by Jim Fisk on March 6, 2013 at 6:36am

Hey guys,

There is a huge difference between sealing against air versus water. I of course made this for water and it seals great but for air it will need a little more fine tuning like sanding off the seam on the ball more completely. These blue balls were 6 for a dollar at Walmart but a better higher quality ball will work better from the get go I'm sure. At the time I made the valve I still only had a concept in my head so didn't want to blow much cash on it. Turned out that I already had everything else I needed sitting right in the GH as I sell my siphons on Ebay and keep parts in stock which worked perfectly with very minor alterations. Basically just some scraping with a knife. I have flapper valves in metal but none in plastic. That could be easier of course (but less fun). Haven't looked. Most sump pump valves use a spring and of course I didn't want that. This came together in about 20 minutes, fit the pipes without any more adapters (which can cost more than the valve) and should work in any position. I have dealt with many sump check valves and have found them to be notoriously failure prone.

Comment by Chris Carr on March 6, 2013 at 1:30am

How good of a seal do you get on the ball? I like your method as it is quite flexible but some folks may find that a flapper check value would work good too if they could get one that fit the size they needed. An image search for "sewer check value" or "flapper check value" will give a good idea of what to look for at a hardware store. I know Glen Martinez used these in his initial design for airlift pumps a while back. 

Comment by Paul Letby on March 5, 2013 at 3:50pm

Looks sound to me.  Well thought out.

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