Barnwood Keezer

[rwc_617]

@d_rock, the area of a circle is pi*D^2/4, so your 4-in-diam input fan has an inlet area of 12.57 sq-in, but your four 1-in-diam exit holes only have a combined exit area of 3.14 sq-in. A computer fan can probably not generate the pressure needed to create an exit velocity four times that of the inlet velocity (conservation of mass for incompressible flow) so you are probably not moving very much air. Recommend you enlarge your exit holes to 2-in-diam to match the input area of the fan.

 

[d_rock]

Why not try to layer a couple more layers of foam around the coffin to see what that will do to ur temps? I like ur setup.

I didn't add foam to the front of the coffin around the taps simply because of space. I bought the thicker foam and it would block airflow from the fan to the faucet shanks. There is foam on the back panel that comes off the coffin, and all joints are caulked. The fan is always on, so my layman's reasoning says that airflow is more important than temperature retention in the coffin itself.

@d_rock, the area of a circle is pi*D^2/4, so your 4-in-diam input fan has an inlet area of 12.57 sq-in, but your four 1-in-diam exit holes only have a combined exit area of 3.14 sq-in. A computer fan can probably not generate the pressure needed to create an exit velocity four times that of the inlet velocity (conservation of mass for incompressible flow) so you are probably not moving very much air. Recommend you enlarge your exit holes to 2-in-diam to match the input area of the fan.

I do appreciate your calculations on my behalf, but consider this:

The intake hole under the fan is slightly smaller than the diameter of the fan, say 3" (I can guarantee my jigsaw cut circle is not perfect ). So the inlet area of a 3" hole would be around 7 sq in. That measurement doesn't take into account the surface area of the fan/motor/chassis blocking airflow in, however. The fan motor itself (center of the fan blade assembly) is around 1" in diameter (.79sq in), not to mention the chassis braces that cross the fan opening, so with the motor and chassis we'll consider approximately 1sq in of area to block airflow- that would make the actual inlet area around 6sq in. The four 1" holes have approx. 3.14sq in inlet area.

You are right that my in/out balance is off, but after looking at it like this, it's less than 2x rather than 4x. I may add two more 1" holes, but it's all together now and I'm seeing about a 8-9 degree differential between the coffin and keezer. Seems like that's about the best that people are getting with separate coffin boxes, so I'm good with that. No issues with foaming and my taps are cold enough to condensate when I pour, but not so cold that they sweat at other times. I think it's a good balance.

I am considering rebuilding my lid/coffin altogether, to make sort of a collar/coffin combo. It would allow a keg on the hump, while still having a 6-8" lower ledge on the front of the lid for a drip tray and faucet overhang.

@DurtyDawg - Sorry to hijack your thread! Your keezer was one of the main examples that really got me set on the coffin keezer option. Great design.

 

[MusicalBrewer]

@MusicalBrewer - Here's my final setup. Nothing fancy at all, I put a 4" PC fan in the tower pulling up, and another 4" fan in the floor of the keezer (I used long screws as posts to keep it 2" off the floor). With just the coffin fan, it kept temps 10-12 deg higher than the freezer temp. I decided to add the second fan in the freezer floor and it seemed to help, it dropped the coffin temp by 2 degrees. Now I'm seeing just under a 10 degree differential between coffin/freezer on average. I'm using Perlick 650SS and 10' of beer line, so any foaming issue is pretty much negated by the equipment, but the cold lines are going to keep that beer in the line fresh.

I plan to make a new keg floor/PVC duct system eventually that will better circulate air in the keezer, and hopefully reduce some condensation issues I'm having.

Hey d-rock, thanks for the update. I'm surprised there is that much temperature differential. It looks like the coffin is fairly small.

There was another thread titled "keezer insulation" (sorry, don't know how to post a link). In it there was a recommendation to use Armaflex 1/2" foam sheet insulation. Apparently this type of insulation is far better at keeping the cold in. I haven't got any yet, but want to give it a try.

I had a pvc floor system in a previous keezer--it was awesome. I didn't put a collar on so I don't have room for it in my current one...otherwise I would do it again. I'll bet when you get that done it will bring the temperature differential down!

 

[DurtyDawg]

Check the R-value of the insulation. The higher the R-value means better insulation value. Ridged foam is usually better in tight applications. Make sure ur joints are caulked very good to stop air loss.

 

[jbb3]

And once you get all your rigid foam insulation installed, I found this stuff is great for sealing things up and adding a few more Rs.