Air movement in keezer

[Catt22]

Thanks, very interesting results so far but a 20F difference?


3 things:

First, the frozen keg in the bottom is acting just like an ice pack inside a cooler, in other words, cooling the surroundings down and making a huge contribution for the stratification.

Second, do you actually have 2 identical thermometers calibrated for top and bottom? That is to make sure they agree with each other instead of over or undershooting the stratification.

Last but not least at all… Are you taking the thermometer reads outside without opening the freezer lid while their temperature probes are inside? If not, when you open that door, you are rushing in 70F room temperature air (if I recall correctly your conditions) that is making a huge difference for the stratification.

First: The kegs are no longer frozen. I turned the freezer off and let it warm up for a day. It has been running for about three days now, so I figure everything is about as stabilized it will get for the first configuration.

Second: I'm using three digital thermometer and they all agree within one degree when tested, so my confidence level is high in that regard. One is the controller and the other two are digital indoor/outdoor thermometers. The controller probe and one thermometer probe are at the bottom of the freezer. The other thermometer probe is a about two inched below the collar.

Lastly: I have not opened the freezer at all for the past four days, so there is no issue with room air rushing in. The temp differential from top to bottom fluctuates from about 17 degrees to 20 degrees over one complete cycle (on period + off period = one cycle). I just checked it right now and there's a 17 degree delta. The compressor shut off a few minutes ago.

Room temp is a very stable 72F. Controller is set at 40F w/a 3 deg differential.

I've only had the patience to time the on portion of the cycle so far and it was right at a 30 minute run time. I got tired of waiting for the off portion to end as it is really long at more than an hour. I'm not sure how much longer, but it could be much more. One very startling discovery is how little power has been used so far. The meter indicates that in 66.5 hours the freezer has used only 0.47 kwh. I don't recall what I'm paying for electricity, but I think it's about 12 cents per kwh or so. What that translates to is a cost of less than two cents per day. I find that to be unbelievably low, but considering how infrequently the compressor is cycling, I guess it's correct. I plan to run the freezer in this configuration for at least a couple of more days to see how consistent the data is before I move on to the second configuration. I will get handle on the off portion of the cycle as well. At this rate, it may take awhile to complete the tests for all four configurations, but it will get done eventually.

 

[Catt22]

Thanks, very interesting results so far but a 20F difference?

Yes, a max of 20 degrees. What does yours indicate?

 

[Clayton]

https://www.homebrewtalk.com/f51/converting-frigidaire-7-2-cu-ft-chest-freezer-162225/#post1873482

Please read one of the last paragraphs in the post, but in case you missed it:



Obviously, I'm not the only one here at HBT who thinks that putting a device that actually creates heat inside a closed, small, and insulated space (the way central heat systems are supposed to work) will warm it up and wear the compressor.

Just because the majority does something, it does not mean it is the smartest thing to do... don't take me wrong, I'm just laying down our options here... trying to have a healthy discussion and hopefully be helpful.

all commercial kegerators and coolers for that matter have fans, and for good reason the move air cools warm kegs much much faster. i have a few fans in my kezzer that i turn on when a new keg is added, but i dont run them all the time.

 

[Indyking]

Thanks, very interesting results so far but a 20F difference?

Yes, a max of 20 degrees. What does yours indicate?

Good, look like you designed it well to minimize the variables.

Most chest freezers operate in the range of 0 to 10F. My chest freezer empty set in the highest temp keeps the temperature in the bottom at around 10F as measured by an outside thermometer with a probe inside set in the bottom (never opening the lid). My point is, a 20F stratification would mean that the temp in the top of the freezer would reach 30F (10+20), which has never happened in my feezer even when full of stuff and running in highest temperature setting to conserve energy. My stuff in the top of the freezer had always kept frozen as it ever was! In other words, any chest freezer of any size running in good condition would likely never have a 20F difference between bottom and top.

Remind me how tall the collar is?

 

[Catt22]

Good, look like you designed it well to minimize the variables.

Most chest freezers operate in the range of 0 to 10F. My chest freezer empty set in the highest temp keeps the temperature in the bottom at around 10F as measured by an outside thermometer with a probe inside set in the bottom (never opening the lid). My point is, a 20F stratification would mean that the temp in the top of the freezer would reach 30F (10+20), which has never happened in my feezer even when full of stuff and running in highest temperature setting to conserve energy. My stuff in the top of the freezer had always kept frozen as it ever was! In other words, any chest freezer of any size running in good condition would likely never have a 20F difference between bottom and top.

Remind me how tall the collar is?

I have three freezers total. One is a chest freezer (serving freezer with the collar and taps). Another is an older upright freezer with the coils in the shelves that I use only for food storage and the third is a commercial freezer intended for restaurant use. Any of the three will easily maintain sub zero temperatures. I've had all of them down near 10 below just to see what they could do.

The reason you're not seeing the large temperature difference between the top and the bottom is that you don't have an uninsulated collar installed. At least I don't think you do as there would be no reason for a collar if you are using it as a food storage freezer. So, you are comparing apples to oranges as they say. The uninsulated collar is the difference and apparently it's a major difference.

The collar is made of nominal 2 X 6 pine. Actual height is about 5-1/2".

 

[BrewMoreBeers]

I agree the insulated collar is a huge difference. I timed mine pre-insulation and it cycled something like 15 min on, 30 min off. Post insulation it now runs 10 min on, 45 min off.

 

[Catt22]

Update (again)

Configuration #1
No Fan/No Insulation on Collar
Set Point 40 F w/3 deg differential
Controller Probe at Bottom of Freezer
Ambient 72F
Compressor On: 30 minutes
Compressor Off: 150 minutes (2.5 hours)
Complete Cycle duration: 3 hours
Taps @: 69 F
Collar Exterior @: 69 F
Compressor cycles on for 30 minutes and off for 2.5 hours
Poured Beer Temp (actually water for the tests): 40 F
Average Temp Difference Bottom vs Top: 17 deg F

 

[Clayton]

i dont think its just the collar , it just like those open top freezers in the supper market cold does not rise. and in the chest freezer the coils go all the way up to the lip at the top

 

[BrewMoreBeers]

...cold does not rise.

It has nothing to do with "cold" moving. It has to do with heat from the room transferring through the collar and into the cooled space.

If one wants to get technical, "cold" does not exist. Rather, "cold" is perceived difference in the amount of heat in a given system. "Cold" does not radiate out of a kezzer, heat radiates into a kezzer. Hence the warmer top layer and the need to insulate the collar to limit heat transfer from the room into the kezzer.

 

[BrewMoreBeers]

Catt22... How us the test coming along.

 

[Catt22]

Catt22... How us the test coming along.

Well, I've had it running in configuration #2 for several days, but I haven't timed the cycle yet. I should be able to do it this evening. I have observed that the cycle is considerably shorter and the energy consumption is higher, but it still isn't using much power. We anticipated that though, so no surprise there. If I can get #2 done tonight, I may be able to install the insulation tomorrow. Once the insulation is installed, I will let it run for a couple of days to stabilize before timing it for #3.

 

[ckwatkins]

Catt22 any updates???

 

[Catt22]

Catt22 any updates???

A partial update at least. I still have not gotten around to insulating the collar, but with the fan running continuously and the probe in the center and on the floor of the freezer the total cycle time is about 2-1/2 hours with the compressor running for about 35 minutes and off for about 2 hours. Average power consumption over a 137 hour run was 6.65 kwh or about 14 cents per day.

I'm brewing today, but might be able to get the insulation installed in the next couple of days. I know, you've heard that before, but this time I mean it!

 

[JRems]

Sorry if this was posted earlier and I missed it, I wanted to know what these "muffin fans" are and where I can buy one locally? They look like computer fans but 110v not 12v I was looking for one for my kegerator but only saw 12v ones. Where do you guys get them?

 

[Catt22]

Sorry if this was posted earlier and I missed it, I wanted to know what these "muffin fans" are and where I can buy one locally? They look like computer fans but 110v not 12v I was looking for one for my kegerator but only saw 12v ones. Where do you guys get them?

Radio Shack has the 110v AC muffin fans. You can probably find them cheaper somewhere on line, but with shipping etc there might not be much savings to be had.

 

[SpanishCastleAle]

Maybe it's because I don't have towers but instead have Perlicks penetrating the front of the collar and my collar is insulated but it doesn't seem that I need a fan in my keezer. The kegs are always at the same temp and I never get warm or foamy pours, even in Florida summer where my garage gets pretty hot. I tuck the beer lines in between kegs so they are near the bottom.

Or maybe I'm just lazy and like things as simple as possible.

 

[Hang Glider]

In my 7cu ft GE chest freezer, the coils only go around the top few inches - and then the "cold falls" into the rest of the chamber - when the humidity/moisture is high, I was getting an ice ring around the top 4 inches but not below. When it's running, it feels very cold around those top four inches, and not so much elsewhere.
That said, even though heat rises and cold sinks, parts of my beer would occasionally freeze as well (mmmm..eisbeer!).

The fan prevents the freeze-ups, both in the beer and in the chamber.

Jrems - you can go either 110V or 12V - Mine is mounted much like Catt22 - on the lid - but I'm running an old computer fan - wired to an old cellphone charger. (thinner wires under the seal!)

 

[JRems]

Thanks, I'll check out radio shack. I would rather not do 12v I wanted to tap into the power after the temp controller so the fan only runs when the kegerator turns on. The thicker wires are no problem. The wires will run out the same hole in the back as the temp probe. I also have other holes back there for the co2 lines to enter so even if I had to add another hole it would be no problem. ( easy since no coolant lines in any of the sides or back)

 

[SpanishCastleAle]

In my 7cu ft GE chest freezer, the coils only go around the top few inches - and then the "cold falls" into the rest of the chamber - when the humidity/moisture is high, I was getting an ice ring around the top 4 inches but not below. When it's running, it feels very cold around those top four inches, and not so much elsewhere.
That said, even though heat rises and cold sinks, parts of my beer would occasionally freeze as well (mmmm..eisbeer!).

The fan prevents the freeze-ups, both in the beer and in the chamber.

Jrems - you can go either 110V or 12V - Mine is mounted much like Catt22 - on the lid - but I'm running an old computer fan - wired to an old cellphone charger. (thinner wires under the seal!)

My keezer also has the coils near the top and there is an ice ring when I run it at colder temps (like when I'm about to bottle from a keg). When I bottle I usually run it where a jar of water on the hump shows 33*-34* F and it's never frozen beer. To get rid of the ice ring I just let it warm up a bit (which I normally do after done bottling anyway) and it melts, then when I change out the next keg I use a towel and some long SS tongs to reach to the bottom and soak up the water.

 

[letzleta]

I know this is a very old thread, but I was interested in any more results Cat22 found.
1. Have you completed any other tests?
2. Do you have an opinion on fan vs no fan?
3. Do you have an opinion on temperature probe placement?

Thanks in advance.

 

[Hang Glider]

Glider here - (not Catt)

consensus is generally around fan as a necessary component to mitigate freezing the bottom of your keg

temp probe - if used as a fermenting chamber, should be taped to carboy

if only used as keezer, sitting in a container of water will minimize the effects of opening the top.