Huge temperature stratification in Keezer despite having a fan installed?

[drgonzo2k2]

Hey, gang, I could use a little help here. Back in October I built myself a nice little 6 tap keezer. You can check out the pics and specs in my post here if you're interested. Initially everything was great with the setup, and I was a very happy home brewer, but then I noticed over the course of November, as I was filling it up with kegs (and emptying said kegs), they would go from perfect pours, to foamy pours.

I also noticed that after having a keg tapped for about a week or so I would start getting bubbles in the beer lines. At this point I've got 6 kegs in there, and they all have this problem. This leads to "stuttering" pours, and a lot of foam. I did a bit of research, and it seems this can be caused by a few things:

1) Simply over-carbing your kegs

2) A CO2 leak somewhere

3) Big temperature differences between the bottom and top of the freezer

Well, I was pretty sure #1 wasn't the issue, as I was following the 30 PSI for 24 hours, purge CO2, and set to serving temp for a couple of days that seems to work well for a lot of folks.

I was also pretty sure there wasn't a CO2 leak anywhere, as I'd gone over the whole system with leak detector spray twice already, but I gave it another shot, and sure enough, there still aren't any CO2 leaks.

So, I decided to see if I was getting temperature stratification in the keezer. Yesterday morning before work I placed a jar of water on the floor of the keezer and another on top of one of the kegs. I already keep my temperature probe immersed in a jar of water that's the same size, which sits on my keezer hump, so it's about 1/4 - 1/3 of the way up. I figured 3 jars in this configuration should allow me to measure bottom, middle, and top freezer temps. This morning before work I checked all of the temps with my Thermapen, and here's what I found:

• Bottom - 34F
• Middle - 40F (which is what I have my temp regulator set to and matched the value measured by my probe)
• Top - 47F

Just to double check everything I also did 3 small (6 oz or so) pours from a keg and measured those temps:

• Pour 1 - 45F (and mostly foamy)
• Pour 2 - 42F (not quite as foamy)
• Pour 3 - 38F (and poured perfectly)

So it would seem I've found the problem, but I'm a bit baffled. If you looked at the pictures you'll see that I have a nice sized fan in the keezer. It's this particular model if you're interested. It's a 120mm fan rated at 51CFM.

As it stands now I've got the fan mounted so it's blowing upward, my thinking being that it should suck the cold air from the bottom towards the top. From what I'm reading, at 51 CFM, it really shouldn't matter what direction it's blowing as it should circulate all of the air in the keezer no problem. Despite that I was thinking I might try reversing the fan, so it blows the warm air downward when I get home this evening, but beyond that I really have no other ideas on what to try.

Any help that anyone can offer would be greatly appreciated!

 

[drgonzo2k2]

Oh, just occurred to me that I may have put this in the wrong section. Admins, if this belongs in the DIY Kegerator/Keezer section please feel free to move!

 

[HausBrauerei_Harvey]

I cant offer any advice other than try some different mountings of the fan like you plan. I did a lot of research when building my setup and some folks built some baffel like thing from the bottom of keezer to the top near the taps and ran the last bit of line up through that, with a fan at the bottom, seemed to help combat foamy pours. perhaps try a second fan if you can fit it first.

 

[drgonzo2k2]

Hey, thanks for the response. I'd been doing a bit of Googling this morning and see that some people have used PVC to build baffles that run from the bottom of the freezer up to the top to help pull cold air up a bit.

I think I might give that a shot if reversing my fan direction doesn't have any affect, or if anyone else doesn't have any good suggestions.

The funny thing is that I actually already have a second fan installed. I ran into a bit of a moisture problem so I added a smaller fan (80mm I think) to my EVA-DRY which solved that. It sits on the hump, in front of where my jar of water containing my temp probe sits.

 

[rmarshall100]

So, you are running your fan off a separate power cord so that it runs constantly, right? If not, this is your issue: The temperature regulator unplugs the entire freezer whenever it shuts off thus allowing your keezer to stratify due to lack of air flow.

 

[ScrewyBrewer]

From the picture in your build thread the beer lines seem to extend down to the bottom of the keezer, I have similar setup as well but no foaming issues. Which temperature controller are you using, and have you tried set-and-forget carbonating your beer with the cO2 at 10-12psi? I did replace a ball-lock beer connector once because of a foaming issue, after trying just about everything else, and that actually solved the issue for me.

 

[drgonzo2k2]

So, you are running your fan off a separate power cord so that it runs constantly, right? If not, this is your issue: The temperature regulator unplugs the entire freezer whenever it shuts off thus allowing your keezer to stratify due to lack of air flow.

Yep, the fans (both of them) are running constantly, not controlled by the temperature regulator.

From the picture in your build thread the beer lines seem to extend down to the bottom of the keezer, I have similar setup as well but no foaming issues. Which temperature controller are you using, and have you tried set-and-forget carbonating your beer with the cO2 at 10-12psi? I did replace a ball-lock beer connector once because of a foaming issue, after trying just about everything else, and that actually solved the issue for me.

No, the beer lines are coiled on top of each keg. I'm using the ITC-308 controller, and it seems to be dead-on accurate according to my Thermapen.

I've not tired the "set it and forget it" method as overcarbonated kegs don't seem to be the problem here. If the kegs were overcarbonated, wouldn't every pour be foamy? In my particular instance the first pour is very foamy, 2nd pour a little foamy, and 3rd pour is perfect, which to me would indicate the kegs are properly carbonated but there's a temperature problem.

 

[ScrewyBrewer]

@drgonzo2k2 do you have the ITC-308 controller's temperature probe submerged in liquid inside the keezer, or is it reading the ambient air temperature? Have you tried putting the coiled beer lines on or near the colder floor area of the keezer?

 

[drgonzo2k2]

@drgonzo2k2 do you have the ITC-308 controller's temperature probe submerged in liquid inside the keezer, or is it reading the ambient air temperature? Have you tried putting the coiled beer line on the floor of the keezer?

It's submerged in liquid.

 

[doug293cz]

Is there space between kegs, and between kegs and keezer walls? If not, then airflow around the kegs and in the space below the top of the kegs will be little to none. You need some spaces in order for the air to circulate, even with a fan.

Brew on

 

[drgonzo2k2]

Is there space between kegs, and between kegs and keezer walls? If not, then airflow around the kegs and in the space below the top of the kegs will be little to none. You need some spaces in order for the air to circulate, even with a fan.

Brew on

Well, that's a good question. Things are in there pretty tight, and I am maxing out the capacity of the freezer according to this post.

I've got 6-ball lock kegs, and as you can see from that diagram, it's a tight fit, but they do fit, and there's just a bit of space around them (my configuration matches that of the Min. Collar - 8 7/8" drawing from there).

As it stands now though, I've blown through 2 of the 6 kegs that I started with, so it's down to 4, and thus more free room in the freezer, and I'm still having this issue.

 

[flars]

Try moving the jar your temp controller probe is in off the compressor hump. This may be a warm area from the heat produced by the compressor. Hang the jar halfway down the side of a keg.

 

[drgonzo2k2]

Try moving the jar your temp controller probe is in off the compressor hump. This may be a warm area from the heat produced by the compressor. Hang the jar halfway down the side of a keg.

Thanks, but I actually thought that might be an issue. Well, actually I thought it might be the opposite problem, that the glass jar was sitting right on top of a coolant line, so it got really cold before the rest of the freezer had a chance to cool down. Due to that I went ahead and set it on top of my EVA-DRY so it was not sitting directly on the hump when I took the measurements in my first post.

As it stands now my two ideas are to reverse the fan so it's blowing the warm air down (as opposed to trying to blow cold air up), and if that doesn't work trying to attach some sort of baffle to it so it can more easily suck cold air up from the bottom of the freezer.

 

[drgonzo2k2]

Thought I'd keep this thread updated in case anyone was following along. I've been struggling with this since my post last week. I tried pointing my single 120mm fan down instead of up. I removed my 80mm fan from my EVA-DRY, set it up in the opposite corner of the 120mm fan and then tried various combinations of one fan pointing up while the other pointed down, the opposite of that, one pointing up while the other was blowing horizontal across the kegs and shanks, and so on.

No matter what I did I couldn't really improve over the original situation, and in some cases it just made it worse. Some combinations would get both the temperature probe (middle of keezer) and top of the keezer to be the same at 41*F; however, that would result in the bottom of the keezer being 32*F, so that was a bit scary, and the beer was just as foamy as ever.

From reading older threads on here, it seems like 2 things could help here:

1) Raising the kegs so they're off the floor of the keezer a bit so the air can move around down there

2) Adding a PVC baffle to one (or both) of my fans with some holes drilled in the bottom to serve as an uptake to pull the cold air up from the bottom to the top

Since I had an extra shelf from the stand up freezer that I use as my beer cellar (kept at 53*F) that I'm not using, and that was the correct width to fit, I just used that and took a hacksaw to trim it to length. I just put that in under the kegs on the floor, and we'll see how it goes. Right now there are 2 kegs on it, and it's holding up pretty well, but to hold 4 I think I'll need to add another support of some sort in the middle to keep it from bowing in. I'm sure I've got something out in the garage that'll work.

I figure I'll give that a go at first since it's free, see how it goes, and then either add in the extra support and/or a baffle to the fans. Right now I've got one blowing down and the other up, and I'll check the temps again tomorrow morning before work.

 

[NeoBrew]

Try putting the circulation fan in the BOTTOM of the freezer pointing up. I didn't go back and look at your pictures, but I assume you are using a computer fan. They don't have much power to suck up into them. I found that putting it down into the cold and blowing up made a huge difference. My best success was putting it down at the bottom below the tap shanks and making sure they were getting bathed in cold air.

Ultimately what matters is that the beer is cold all the way from the bottom of the keg to the tap. So coiling the lines in the bottom of the keezer is going to help.

Eventually I made a ducted contraption that locates the fan at the bottom with the outlet at the top. I put this "tower" just next to the shanks. It's made a big difference in the quality of my pours.

The other thing I've noticed is that balance in the pressure is critical. If I set my pressure up a few psi I get way more foaming than if I keep it at my normal 12-13.

 

[drgonzo2k2]

Hey, thanks, I appreciate your help! I'm not using computer fans, but to be honest, I'm not sure how powerful they are compared to those. They directly plug into AC. Here is the 120mm and here is the 80mm.

I haven't tried putting the fans on the bottom, but I was a little nervous in case of moisture, but I guess since I've got a shelf down there now, unless it floods that shouldn't be an issue. I'll give that a shot next after seeing the results from adding the shelf.

 

[drgonzo2k2]

Keeping this thread updates as it seems I am finally making some progress here!

When I started, measuring the temp of jars of water placed at three different levels in my keezer yielded three very different measurements:

• Bottom - 34F
• Middle - 40F (which is what I have my temp regulator set to and matched the value measured by my probe)
• Top - 47F

Installing the wire shelf on the floor of the keezer, to lift the kegs up, as I mentioned in my last post did have an impact, which resulted in:

• Bottom - 33F
• Middle - 40F (which is what I have my temp regulator set to and matched the value measured by my probe)
• Top - 43F

So that basically shifted it from a 13* difference to only a 10* which is better, but I was still getting foamy pours, and I wasn't happy with the bottom of the keezer at 33*.

So, as NeoBrew suggested, I took one of my fans and placed it in the bottom of the keezer on the shelf so it was blowing cold air up. I left the second fan in the opposite corner blowing down.

This morning I checked and was happy to see:

• Bottom - 36.7F
• Middle - 40.1F (which is what I have my temp regulator set to and matched the value measured by my probe)
• Top - 38.7F

That was at 5 am this morning, so I didn't pour off a pint for quality control; however, checking the beer lines I saw only a couple of very small bubbles in any of them (some had none) whereas previously they were all just full of bubbles. Definitely looking forward to getting home tonight and pouring a beer!

I think my next step is to add the supports to the wire shelf as it is bowing a bit with just the 2 kegs there now, and I'd like to make sure there's a good couple of inches of air space down there even when completely full. Then I probably just need to play around with the location of my jar containing my temperature probe. Right now it's off to the right side, on top of the hump, and the fan blowing down is definitely hitting it with the warmer air from above. I'm guessing that's why it is at 40 while the jar above it is a bit cooler. The freezer probably needs to work a bit harder to keep it at 40 than the rest of the freezer as it's in a warm zone, so it gets to 40, but the rest of the freezer overshoots a bit.

Either way this seems to be light years ahead of where I was this time last week, and I'll keep plugging away until I get it dialed in perfectly!

 

[doug293cz]

Sounds like you're getting it under control.

Brew on

 

[HausBrauerei_Harvey]

nice, I wonder if lifting the kegs isn't really needed, as it seems the fan placement did alot to help out. Now you have me wanting to get my system dialed in a bit better as well!

 

[drgonzo2k2]

To be honest I probably wouldn't be comfortable with the fan where it is if it wasn't on top of that shelf. The shelf raises the kegs up off the floor about 2" or so, which puts the fan safely out of harms way should moisture start to collect down there. I think having the shelf down there helps, as when it is loaded up with 6 kegs, there's not a whole lot of room, so anywhere that air can circulate is probably good.

Last night when I got home I forced myself to have pours from 3 different kegs for QC purposes and all 3 of them were very acceptable. Just a tad bit more foam initially then I'd like, but honestly I might just be hyper-critical at this point.

I was pretty happy this morning when I got up and measured temps to see:

• Bottom - 37.3F
• Middle - 40.1F
• Top - 38.3F

 

[doug293cz]

I think the shelf is definitely helping. Allows air flow to go under the kegs, but more importantly up between the kegs, even if they are packed tightly together. Thus you can get bottom to top airflow throughout the entire volume of the keezer.

Brew on

 

[drgonzo2k2]

So I made the final adjustments on Saturday to add some supports under the shelf so it doesn't bow in at all under the weight of the kegs, and I moved my 2nd fan to also be on the bottom of the freezer blowing up. So now there's a wire shelf that lifts all the kegs up off the floor by about 2" and 2 fans in opposite corners both blowing cold air up.

The first thing I noticed after a few hours like this was that all of the taps were cold to the touch again like they were when I first setup the keezer and it was empty. I left it in this arrangement over the weekend and noticed that the quality of the pours continued to approve. I'm happy to report that last night I got multiple perfect pours across a few different kegs over the course of the evening with none of the sputtering or overly foamy pours from before. A visual inspection of all the liquid lines revealed no bubbles in any of them.

So this morning I checked the temps in the 3 jars and found:

• Bottom - 39.1F
• Middle - 40.2F
• Top - 41.1F

So now only a 2 degree difference from the top to bottom, cold shanks and faucets, and perfect pours all around!

 

[doug293cz]

I'd call that a rousing success! Thanks for reporting on your journey. Now I know what to do inside my keezer when I get around to building it.

Brew on

 

[scaglikm]

Reviving an old thread here. I am having similar issues in my keezer. If you are still around care to share the type of wire shelf you are using?

 

[drgonzo2k2]

Reviving an old thread here. I am having similar issues in my keezer. If you are still around care to share the type of wire shelf you are using?

Sorry for the delayed response, but better late than never! I'm using an extra shelf from an old refrigerator. I had to use a hacksaw to trim it down to size a bit, but after that it worked great.

Also, I'm happy to say that 5+ years later the old kegerator is still working A-OK!

 

[scaglikm]

Sorry for the delayed response, but better late than never! I'm using an extra shelf from an old refrigerator. I had to use a hacksaw to trim it down to size a bit, but after that it worked great.

Also, I'm happy to say that 5+ years later the old kegerator is still working A-OK!

Thanks! I ended up buying a high powered computer fan and that has done the trick. I might help out my neighbor with this though. Gave him my old slow fan and old keezer when I upgraded.