My Venturi Fail

So I brewed my first batch of beer today and, thanks to these forums and all of the wonderful advice, I had a lot of confidence that I was starting out a little 'ahead of the curve'....and I am sure that sounds cocky.

Two things that I really thought were imperative to my first brew were an immersion chiller and a venturi insert on my siphon hose.

I build the immersion chiller and, besides needing to lengthen my intake and outtake ends to clear my 7 gallon brewpot, the thing worked amazingly...I had my wort chilled in about 7ish minutes.

On the other hand, my venturi insert was a tremendous bust. I cannibalized my 'L' plastic tube that came with my beginner's brew kit because I bought an autosiphon as well. The OD was perfect so I just scored around the plastic, snapped it off, sanded the edges, and created the hole. That is where I think I made my mistake. I heated up the tip of an awl and perforated the plastic tube that way, and I fear my hole is too big.

When I went to siphon/aerate my wort into my fermenting bucket, I wasn't getting a steady stream at first and it quickly stopped siphoning. I figured that the problem was with the venturi insert as the siphon from the wort to the insert was fine, but there were huge airpockets on the other side of the insert. I covered the hole with my thumb, pumped the autosiphon again, and everything flowed perfectly. So I spent a while adjusting the pressure of my thumb over the hole and created an incredibly vigorous stream of bubbles entering my tubing.....and there was still no foaming in my fermenting bucket...

Where did I go wrong?

First off, the "L" tube is a racking cane. So, if I am understanding you correctly, you cut off a section of the racking cane, punched a hole in it and then attached it to the autosiphon hoping to draw air into the stream flow to the fermenter. The only way I could see this working would be if the opening in the tubing was substantially below the lowest level of the fermenter Even then, it would probably be rather sketchy and difficult to control. Why not simply shake up the fermenter to aerate the wort and forget the venturi thing. IIRC, there's much more to designing an effective venturi device than simply punching a hole in a tube. I've never heard of the technique that you are describing. Where did you hear about it?

I have syphoning man. I can never run one out perfectly.

Do you get a full stream out of your tube with your thumb over the hole? Meaning is the fluid syphoning through the entire length of the venturi or is it just falling out (Gravity assisted out of the tube)? You may be losing syphon that way and it not be very obvious. Try to keep the tube slightly horizontal to ensure a full syphon and see if that helps any. Sorry if it doesn't.

I used to use a venturi (I've switched over to oxygen now) and it worked pretty well. IIRC, I had maybe a couple of feet or 2 1/2 feet of 3/8 tubing coming off my auto-siphon (1/2 inch). Then I had a short (about 1 1/2 inch) piece of 5/16 tubing jammed into the end of the 3/8 tubing, then another section of 3/8 tubing maybe a foot long or slightly more jammed over the other end of the 5/16 tubing. I had a 1/16 inch diameter hole in the middle of the short length of 5/16 tubing. I had enough tubing coming off the auto-siphon that I could put the venturi hole down inside the mouth of the carboy when I pumped the auto-siphon (because the wort would squirt out the hole), then after I got the siphon going, I could raise the end of the tubing up to near the mouth of the carboy to maximize splashing into the carboy. I always got a good stream of bubbles in the tubing and lots of foam in the carboy.

Catt22 said:

First off, the "L" tube is a racking cane. So, if I am understanding you correctly, you cut off a section of the racking cane, punched a hole in it and then attached it to the autosiphon hoping to draw air into the stream flow to the fermenter. The only way I could see this working would be if the opening in the tubing was substantially below the lowest level of the fermenter Even then, it would probably be rather sketchy and difficult to control. Why not simply shake up the fermenter to aerate the wort and forget the venturi thing. IIRC, there's much more to designing an effective venturi device than simply punching a hole in a tube. I've never heard of the technique that you are describing. Where did you hear about it?

Click to expand...

https://www.homebrewtalk.com/f51/cheap-easy-aeration-gadget-68218/

Not that you can tell much from this pic, but here is how I had my insert set up.

I used a portion of the racking cane (thank you for the term) and I made sure that there was at least 2 feel of tube on the fermenter end of the setup as well....

I did have my brewpot higher than my fermenter though...does that make a difference for siphoning?

Not to knock on what you are doing, but have you tried just putting your settling bucket on a table and your fermenting bucket on the floor and just opening the valve and letting is splash down? S'wat I do.

This only matters if you are using buckets though.

I did not use a settling bucket for this batch, I just whirlpooled it and let it settle in the brewpot before siphoning to the fermenting bucket.

I am just a DIY-er at heart and love working on projects, so the Venturi seemed like a no-brainer for me based on the results I was reading about.

the key to a good venturi effect is that the tiny hole has to be at a restriction point in the siphon.

If you have a 1/2" racking cane with 1/2" tubing, put a small piece of 3/8" or 1/4" cane inline where the tubing goes vertical from the pot. Put a tiny hole in the piece of cane.

The short restriction in the siphon causes the liquid to speed up and drop pressure. The drop in pressure pulls air through the small hole. If you use a piece of cane that is the same size as the cane used to siphon, you won't get the pressure drop and it won't work

Hope that helps

Hole is too big...you loose siphon by drawing in too much air. Need only a small hole (or two).

Rebuild and try with a pot of water until you get your desired results. I simply use this these days...

http://www.midwestsupplies.com/siphon-sprayer.html

Good luck.