Air movement in keezer

[Indyking]

to those folks, may i suggest that you always pour your brews in the dark to avoid the energy use of the light bulb (which is likely greater than the consumption of the fan) and the heat generated by the light bulb (which will undoubtedly cause your keezer to cycle more frequently).

Except we don't let the lights on 24/7... but it's OK, I'm getting fine with the cost-benefit of a small fan...

 

[Indyking]

Find a 6 to 12v DC power source and connect the power or hot wire to fan’s Red wire and a ground to Black wire. You can use the same phone chargers people use for Stir Plates and route it inside to the fan. A 6v charger would be fine because it does not need to blow a lot of air. I went with a bearing type because it last longer and temps do not affect it as much as bushing type fans.

Also, since you are not concerned with size, you could go with a 140mm fan. The bigger fan would move slightly more air on any given voltage.

Thanks, so, those computer cables that comes attached to those fans have the live wire in red and the neutral wire in black? Is that what you're saying? How about their third wire? I doubt it is a ground...

 

[devilishprune]

I think the third wire is usually an RPM speed control from the computer. You can leave that disconnected.

 

[Beer_Guy]

You can hook the wires up either way, it is just that the fan blades are more efficient if turning the correct way. The fan housing will have an arrow on the side to show wind direction.

And yes RED is hot, Black is ground or common. The third wire is a speed sensor not speed control. You do not need that ability unless you get REALLY nerdy with your setup.

[I started to get real nerdy in my write up, but hey, this forum is about beer not computer wiring.]

 

[shroomzofdoom]

[I started to get real nerdy in my write up, but hey, this forum is about beer not computer wiring.]

You can also simply modify speed with voltage input...all other factors being equal. A 12v fan with a 9v input will run roughly 3/4 speed, 6v input for 1/2 speed, etc and so on

You want to talk nerdy? Hooking up your fans to an adjustable power supply for 'fine tuning'....:rockin:

 

[TomSD]

You can also simply modify speed with voltage input...all other factors being equal. A 12v fan with a 9v input will run roughly 3/4 speed, 6v input for 1/2 speed, etc and so on

You want to talk nerdy? Hooking up your fans to an adjustable power supply for 'fine tuning'....:rockin:

The only catch to that is most motors have a starting power requirement. As long as you get over that it will operate as you describe. Fans for the most part have a damn low starting power requirement though so it shouldn't be much of an issue.

As for controlling fan speed... I use a universal power adapter that goes from 3v to 12v. I used that to play around with how much power I needed to give my bilge blower and settled on 3v.

 

[shroomzofdoom]

The only catch to that is most motors have a starting power requirement. As long as you get over that it will operate as you describe. Fans for the most part have a damn low starting power requirement though so it shouldn't be much of an issue.

As for controlling fan speed... I use a universal power adapter that goes from 3v to 12v. I used that to play around with how much power I needed to give my bilge blower and settled on 3v.

Good point, most of the 12v fans I worked with had a starting voltage of 6v.

 

[Indyking]

You can hook the wires up either way, it is just that the fan blades are more efficient if turning the correct way. The fan housing will have an arrow on the side to show wind direction.

And yes RED is hot, Black is ground or common. The third wire is a speed sensor not speed control. You do not need that ability unless you get REALLY nerdy with your setup.

[I started to get real nerdy in my write up, but hey, this forum is about beer not computer wiring.]

Awesome, tanks!

 

[Indyking]

Good point, most of the 12v fans I worked with had a starting voltage of 6v.

The only catch to that is most motors have a starting power requirement. As long as you get over that it will operate as you describe. Fans for the most part have a damn low starting power requirement though so it shouldn't be much of an issue.

As for controlling fan speed... I use a universal power adapter that goes from 3v to 12v. I used that to play around with how much power I needed to give my bilge blower and settled on 3v.

Thanks guys, but how about current (amperage)? I have a whole bunch of AC to DC transformers at home that range from 3 to 12V but the current at them (0.4-2A) are all above the rated current for the 12 mm computer fans I found so far (usually 0.15-0.3A), and I looked at a lot of them!

Is that OK to use lower voltage (I was thinking 6V) but higher amperage (like 0.4A) in a fan rated 12V/0.25A for instance? I know I can go lower for the voltage but not sure if I should match the amperage exactly or could go higher or lower???? Help please!!!!

 

[shroomzofdoom]

Thanks guys, but how about current (amperage)? I have a whole bunch of AC to DC transformers at home that range from 3 to 12V but the current at them (0.4-2A) are all above the rated current for the 12 mm computer fans I found so far (usually 0.15-0.3A), and I looked at a lot of them!

Is that OK to use lower voltage (I was thinking 6V) but higher amperage (like 0.4A) in a fan rated 12V/0.25A for instance? I know I can go lower for the voltage but not sure if I should match the amperage exactly or could go higher or lower???? Help please!!!!

Lower voltage of power supply=ok. Fan will just run at lower speed. (see starting voltage exception above)
Higher amperage of power supply=ok. Fan will only draw what it needs from the power supply. Don't go lower amperage on power supply or it could heat up.

.4A power supply+.25A fan should be just fine.

(however, standard disclaimers apply...dont electrocute yourself...I am not an electrician...YMMV, etc)

 

[Indyking]

Lower voltage of power supply=ok. Fan will just run at lower speed. (see starting voltage exception above)
Higher amperage of power supply=ok. Fan will only draw what it needs from the power supply. Don't go lower amperage on power supply or it could heat up.

.4A power supply+.25A fan should be just fine.

(however, standard disclaimers apply...dont electrocute yourself...I am not an electrician...YMMV, etc)

Thank you...

About the disclamer... it's not likely a 6V DC source could cause any damage but you never know...

 

[Catt22]

Update on the fan vs no fan with and without the collar insulated. Well, I have four kegs in the freezer filled completely with water only. I did some preliminary testing to sort of figure out where to place the controller probe and what differential to use on the controller. The placement of the probe makes a big difference. I found that with the probe mounted in the air near the top, there was a huge temperature difference between the top and the bottom of the freezer. So much so, that the temps would way undershoot at the bottom to as low as 22 F with the controller set at 40F using a 3 deg differential. I've since moved the controller probe to the very bottom and ran it that way for another 24 hours to let things stabilize. With the probe at the bottom the undershoot is much less severe at only about 10 degrees or so, but there's a 20 deg F difference from the top to the bottom. The compressor is running much less and using a lot less power without the fan running, but that was expected. It's not a small difference.

 

[BrewMoreBeers]

Update on the fan vs no fan with and without the collar insulated. Well, I have four kegs in the freezer filled completely with water only. I did some preliminary testing to sort of figure out where to place the controller probe and what differential to use on the controller. The placement of the probe makes a big difference. I found that with the probe mounted in the air near the top, there was a huge temperature difference between the top and the bottom of the freezer. So much so, that the temps would way undershoot at the bottom to as low as 22 F with the controller set at 40F using a 3 deg differential. I've since moved the controller probe to the very bottom and ran it that way for another 24 hours to let things stabilize. With the probe at the bottom the undershoot is much less severe at only about 10 degrees or so, but there's a 20 deg F difference from the top to the bottom. The compressor is running much less and using a lot less power without the fan running, but that was expected. It's not a small difference.

Did you have a fan in it?

 

[Catt22]

Did you have a fan in it?

No, initially I simply turned the fan off. The controller probe was mounted in the air stream of the fan close to the top of the freezer (probe maybe six inches below the lid). The differential was set at 5 degrees which is what I had been running it at for a long time. I ran it this way for about 24 hours or so. I think the lower part of the kegs must have frozen or partially frozen. The problem was that the bottom of the freezer got very cold while the top remained much warmer. With the probe at the top, the compressor cycle would start even though the bottom of the freezer was still well below 32 F. That's when I realized that having the probe near the top without the fan running was not going to work at all. I moved the probe to the very bottom of the freezer thinking that will be the coldest area and this would prevent the severe undershooting. It has been more than 24 hours and the freezer has not cycled even a single time. The temp near the bottom has remained quite cold at 35-38. It's rising, but very slowly. I think that the kegs were more frozen than I realized and it's simply taking a long time for them to thaw and for everything to equalize. I will leave it in this configuration until I can get it to cycle in a steady pattern. I did reduce the differential setting to 3 degrees, down from the previous 5. The analog controllers have a fixed differential of 3 deg IIRC, so i thought that would be a reasonable setting for the tests. So, I'm still fooling with the variables to figure out the best way to run the tests. This is not as simple as I thought it would be. The temperature difference from top to bottom has remained at about 20 deg F for the past 24 hours (58 F @ top, 38 F @ bottom). Set point is 40F.

 

[BrewMoreBeers]

i am glad to see you set the differential to 3 degrees. I was going to comment that setting it at 5 was probably contributing to the over shoot on the cooling side... setting it at 38 degrees with a 5 degree differential mean the space heats up to 43 degrees then the compressor kicks on the chills it to 33 degrees - a very long drop. Since it is dropping so far, the unit is getting really cold and when the compressor turns off at 33 the unit is likely to continue to drop for several degrees more.

I think the smaller differential will help give you flatter temperature fluctuations.

i am surprised that the temperature difference is that great between the top and bottom of the space. How much mass do you have in the freezer? These units are designed to function best when they are mostly full. If you have a lot of dead space (i would include "empty" head space in a keg as dead space) that can also contribute to the wider temperature fluctuations due to their being less thermal mass to moderate the temperature.

when i first bought by 15 cubic foot freeze and converted it i only had one full keg and the unit ran a lot. When i added about 4 cases of full bottle and a five gallon bucket of water the extra thermal mass helped keep the temperature more stable and led to less cycling of the compressor once everything reach equilibrium.

 

[Catt22]

I was going to comment that setting it at 5 was probably contributing to the over shoot on the cooling side... setting it at 38 degrees with a 5 degree differential mean the space heats up to 43 degrees then the compressor kicks on the chills it to 33 degrees

i am surprised that the temperature difference is that great between the top and bottom of the space. How much mass do you have in the freezer? These units are designed to function best when they are mostly full. If you have a lot of dead space (i would include "empty" head space in a keg as dead space) that can also contribute to the wider temperature fluctuations due to their being less thermal mass to moderate the temperature.

I have the controller set point at 40F. The compressor starts when it hits 40F and shuts of at 36.9 F with the 3 deg differential. Your controller must be different than mine if it would permit a rise to 5 deg above your set point AND cool to 5 deg below the set point. With a set point of 38 and a 5 deg differential, mine would turn on at 38F and off at 32.9F. It would never get up to 43F as you say yours does.

Yes, the 3 deg differential greatly reduced the undershoot. The freezer cycled this morning for the first time in more than 24 hours, so I guess the frozen kegs have thawed out. there is still roughly a 20 deg temp difference from top to bottom. It's staying steady near 58F at the top and 35-38 at the bottom. This is a 7.5 cu ft freezer with a 2 X 6 uninsulated collar. I have four kegs filled with water to the 5 gallon level, so there is minimal head space and about the normal open space inside the freezer. I'm trying to approximate what happens under more or less normal conditions.

If the freezer cycles with any regularity today, I may be able to log some reliable data for this configuration soon.

 

[BrewMoreBeers]

This is a 7.5 cu ft freezer with a 2 X 6 uninsulated collar.

I made huge efficiency gains when I adda 1.5 inches of ridged foam to the inside of my collar. This will likely save you more energy than tweaking the controller or probe placement. This will also help solve you 20 temperature difference from the top to the bottom. Wood is a very poor insulator.

That said, I appreciate you attention to detail on this project.

 

[Catt22]

I made huge efficiency gains when I adda 1.5 inches of ridged foam to the inside of my collar. This will likely save you more energy than tweaking the controller or probe placement. This will also help solve you 20 temperature difference from the top to the bottom. Wood is a very poor insulator.

That said, I appreciate you attention to detail on this project.

I'm not convinced that insulation alone will mitigate the 20 degree difference in temps from top to bottom, but we shall soon find out. Insulating the collar is on the agenda as a part of this test series. The four configurations will be:

1. Without fan & No Collar Insulation
2. With Fan & No Collar Insulation
3. Without Fan & With Collar Insulation
4. With Fan & With Collar Insulation

The constants will be:

1. 40 F set point
2. 3 deg differential
3. Compressor on at set point and off at set point minus the differential

I'm planning to keep the controller probe at the bottom of the freezer for all tests. This is not how I usually have it positioned, but due to the temperature stratification issue without the fan, I think it's the best location for these test runs.

 

[Beer_Guy]

The temp difference will be less simply because the air at the top will warm up slower.

There will still be stratification, just not as drastic. Every time the unit comes on the walls get cold. The air next to them falls and mixes in warmer air. As time goes by the air up top gets warmer. The quicker this happens the warmer the stratified air up top gets before the probe below senses the need to come on.

 

[Indyking]

I'm not convinced that insulation alone will mitigate the 20 degree difference in temps from top to bottom, but we shall soon find out. Insulating the collar is on the agenda as a part of this test series. The four configurations will be:

1. Without fan & No Collar Insulation
2. With Fan & No Collar Insulation
3. Without Fan & With Collar Insulation
4. With Fan & With Collar Insulation

The constants will be:

1. 40 F set point
2. 3 deg differential
3. Compressor on at set point and off at set point minus the differential

I'm planning to keep the controller probe at the bottom of the freezer for all tests. This is not how I usually have it positioned, but due to the temperature stratification issue without the fan, I think it's the best location for these test runs.

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.

 

[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.