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Old 04-18-2012, 09:40 PM   #11
krazydave
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Just a thought... The skin of the freezer needs to be able to cool down, so if you wrap it up with insulation, you may be asking for problems. You may be able to just add a small air chamber between the freezer wall and your insulation though and use a fan to exhaust the heat. I would think that should be sufficient enough to get the heat away from it.

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Old 04-18-2012, 09:42 PM   #12
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Oh, and by the way. I don't think you need a fan on both sides of your tubes. At that rate, you're sucking the cool air out of the freezer faster than it can make it.

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Old 04-18-2012, 09:51 PM   #13
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Originally Posted by krazydave View Post
Just a thought... The skin of the freezer needs to be able to cool down, so if you wrap it up with insulation, you may be asking for problems. You may be able to just add a small air chamber between the freezer wall and your insulation though and use a fan to exhaust the heat. I would think that should be sufficient enough to get the heat away from it.
Yeah, I figured that out the other day. That back has about 9 inches of space for air flow and there is about 2 inches on the side with the controllers. I'm going to add a few fans to pull out of there when the compressor is running. Would it be a good idea to have at least one fan blowing into that area as well?

I've been thinking the extra fans might be over kill too. I think the biggest issue with the left section was that the freezer skin was exposed to that chamber. Now that it is insulated there I think the fan already installed should do the trick.
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Old 04-19-2012, 01:07 AM   #14
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I don't think you necessarily need an input and output fan so long as there's at least someplace for air to enter if your fan is exhausting, or exit if your fan is sucking cool air in.
Ideals you should have one or the other on the top so that the heat doesn't just rise and get stuck there.

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Old 04-19-2012, 01:25 AM   #15
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I don't think you necessarily need an input and output fan so long as there's at least someplace for air to enter if your fan is exhausting, or exit if your fan is sucking cool air in.
Ideals you should have one or the other on the top so that the heat doesn't just rise and get stuck there.
Thanks for the advice! I'll probably get the fans wired up and installed tomorrow. I'll be sure to update the thread when it's complete.
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Old 04-19-2012, 04:41 PM   #16
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It's not clear to me how those fans are set up. You want to circulate that cold air. Pull cold air from the bottom of the fridge, push it to the bottom of the chamber you wish to cool, and pull (or let it be pushed out) the warmer air from the top of the chamber you wish to cool. If you don't do it that way, you are fighting yourself.

I can't tell, but it looks like you are just pushing cold air into the chambers w/o any path for the warm air to circulate back out? Maybe I don't understand the paths there, or which way the fans are going.

-kenc

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Old 04-19-2012, 09:46 PM   #17
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It's not clear to me how those fans are set up. You want to circulate that cold air. Pull cold air from the bottom of the fridge, push it to the bottom of the chamber you wish to cool, and pull (or let it be pushed out) the warmer air from the top of the chamber you wish to cool. If you don't do it that way, you are fighting yourself.

I can't tell, but it looks like you are just pushing cold air into the chambers w/o any path for the warm air to circulate back out? Maybe I don't understand the paths there, or which way the fans are going.

-kenc
I appreciate your input, but my thinking is a bit different. I'm bringing cool air to the upper part of the chambers where the warmest air will be located. The cool air will then drop to the bottom and warmer air will move to the top to be cooled by the fans again. There should be air movement within each individual chamber due to natural convection. That is why the tube into the top section is not flush with the surface. I was trying to get the cool air to the top so it can cool the warm air.

I think I have it dialed it in pretty well now. I just have to wait for another really hot day to be sure.
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Old 04-19-2012, 10:02 PM   #18
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I appreciate your input, but my thinking is a bit different. I'm bringing cool air to the upper part of the chambers where the warmest air will be located. The cool air will then drop to the bottom and warmer air will move to the top to be cooled by the fans again. There should be air movement within each individual chamber due to natural convection. That is why the tube into the top section is not flush with the surface. I was trying to get the cool air to the top so it can cool the warm air.

I think I have it dialed it in pretty well now. I just have to wait for another really hot day to be sure.
Well, I'm not certain it makes a lot of difference as to the cold air being injected into the bottom or the top, as the fan should get it all displaced pretty quickly anyhow. But the bigger point I was trying to make was, where is the actual circulation?

I'm just not seeing where the full cycle of air in and air out is for the chamber. Maybe I'm just missing it, but it seems like you are pushing air in - but then what? You really want a full return path - in on one end (top or bottom), out on the opposite end.

-kenc
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Old 04-19-2012, 10:19 PM   #19
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Well, I'm not certain it makes a lot of difference as to the cold air being injected into the bottom or the top, as the fan should get it all displaced pretty quickly anyhow. But the bigger point I was trying to make was, where is the actual circulation?

I'm just not seeing where the full cycle of air in and air out is for the chamber. Maybe I'm just missing it, but it seems like you are pushing air in - but then what? You really want a full return path - in on one end (top or bottom), out on the opposite end.

-kenc
The only circulation I have is from the natural convection of cool air falling and warm air rising. If I have issues down the road I'll consider adjusting my design, but it appears to be working so far. I've looked at a number of different fermentation chamber builds and didn't really notice anyone doing what you're talking about.
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Old 04-19-2012, 10:41 PM   #20
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The only circulation I have is from the natural convection of cool air falling and warm air rising. If I have issues down the road I'll consider adjusting my design, but it appears to be working so far. I've looked at a number of different fermentation chamber builds and didn't really notice anyone doing what you're talking about.
Every one I've seen has circulation paths. They might not be obvious, but they are there.

Yes, natural convection will move the air around inside the chamber, that's not the issue. What you want to accomplish is to move the cold air from the fridge over to the chamber and return the warm air from the chamber back to the fridge. You need an in and an out path to accomplish this. It's a bit like putting your mouth on a plastic soda bottle and trying to blow into it - w/o a path for the air to escape, you don't really get any air movement. But put a hole in the other end, and the air moves right through.

It might be working because you get some initial movement and air flowing through leaks and some back through the fan once the pressures equalize. But I bet it runs out of 'gas' when it's more fully loaded, or the fridge might be called on to run too much (probably not, I just don't think you'll get enough air drawn away from the fridge).


Here's a thread with links to a classic design, the baffles, fan on one side, and port on the other provide the 'flow through' circulation.

http://www.homebrewtalk.com/f39/son-...0/#post1067070

Here's a simple approach - remove (or reverse) one of those two fans. Then add the tubing from that fan (or hole) to go down to the bottom of the chamber. That will force air movement through the chamber and back to the fridge. I really do think your results will be rather marginal w/o full circulation. It looks like a really nice build, I'd just like to see you get the most out of it.

-kenc
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