Air movement in keezer

[Catt22]

I guess it would be good put some numbers to prove facts we already know.

And what facts would those be?

 

[shroomzofdoom]

I think that this is mostly B.S. The probe in the water will delay the controller response when it turns the compressor on, but it will also cause it to run longer before shutting it off as there will also be lag in the opposite direction. I don't often open my freezer and then it's usually just to swap out kegs, so this is a very minor issue for me.

I like the idea of placing the controller thermistor into the air loop (right in front of the fan)... This is very similar to what RIMS brewers do with their probe and results in more frequent cycle times--- but smaller inputs, greater efficiency, and more responsive feedback loop. Hence, it's popularity in RIMS.

Since temp controllers are designed to reduce cycling that could harm the compressor (3-5 minute delay), this is also not an issue to be concerned with. If the compressor cycles too often, you can just dial down the temp response and it will process fewer cycles as a function of time.

To me, placing a probe in water is akin to placing a probe before the coil in a RIMS...you are obviating an entire aspect of the feedback loop and delaying the response time for shutoff. Just as RIMS brewers would overshoot their mash temp, a keezer with this configuration would overshoot it's cool cycle. I think this can be negated to some degree by running a slightly higher temp.

Hmmm....if we only had some way of keeping the air volume at a more consistent temperature. Perhaps if we moved the air volume around a bit. Where would one find such a device?

 

[Catt22]

I like the idea of placing the controller thermistor into the air loop (right in front of the fan)... This is very similar to what RIMS brewers do with their probe and results in more frequent cycle times--- but smaller inputs, greater efficiency, and more responsive feedback loop. Hence, it's popularity in RIMS.

Since temp controllers are designed to reduce cycling that could harm the compressor (3-5 minute delay), this is also not an issue to be concerned with. If the compressor cycles too often, you can just dial down the temp response and it will process fewer cycles as a function of time.

To me, placing a probe in water is akin to placing a probe before the coil in a RIMS...you are obviating an entire aspect of the feedback loop and delaying the response time for shutoff. Just as RIMS brewers would overshoot their mash temp, a keezer with this configuration would overshoot it's cool cycle. I think this can be negated to some degree by running a slightly higher temp.

Hmmm....if we only had some way of keeping the air volume at a more consistent temperature. Perhaps if we moved the air volume around a bit. Where would one find such a device?

Spot on IMO. I run a RIMS with the controller probe in the heated wort stream for just the reason you mentioned. Fast response times are the objective. That gives you the real time information you need. The controllers provide the desired options on what you do with that information as you can control the setpoint and the differential. IMO, this is a better way to go than dampening the input sensor by whatever means.

 

[Indyking]

And what facts would those be?

I think most of us agree and/or have observed that the continuously running fan will cause the compressor to be triggered more often, nevertheless I look forward for your experiment because it actually put real numbers to empirical observations. Let me know if you need help with the statistics, I know a little.

Whether or not the compressor runs for shorter or longer periods of time with or without the fan only matters for overall electricity usage, but it does not make any difference for compressor wear. As you have pointed out, most of the compressor wear happens during triggering, so the frequency of engagement is more important than duration of running as far as compressor wear is concerned.

 

[Catt22]

I think most of us agree and/or have observed that the continuously running fan will cause the compressor to be triggered more often, nevertheless I look forward for your experiment because it actually put real numbers to empirical observations. Let me know if you need help with the statistics, I know a little.

Whether or not the compressor runs for shorter or longer periods of time with or without the fan only matters for overall electricity usage, but it does not make any difference for compressor wear. As you have pointed out, most of the compressor wear happens during triggering, so the frequency of engagement is more important than duration of running as far as compressor wear is concerned.

Right, there's no question about the fan running continuously causing the compressor to run more often and increasing energy consumption. That's a no-brainer and was never argued otherwise.

Regarding compressor wear, shorter cycles result in more frequent start ups and a shorter compressor life. Your statements in this regard seem to be in direct opposition to each other. First you say that the cycle durations don't affect the compressor wear, then you follow that up by saying that it does. Can't have it both ways, that's for sure.

 

[Indyking]

Right, there's no question about the fan running continuously causing the compressor to run more often and increasing energy consumption. That's a no-brainer and was never argued otherwise.

Regarding compressor wear, shorter cycles result in more frequent start ups and a shorter compressor life. Your statements in this regard seem to be in direct opposition to each other. First you say that the cycle durations don't affect the compressor wear, then you follow that up by saying that it does. Can't have it both ways, that's for sure.

OK, maybe I wasn't clear. If it is clear that the compressor will run more often with the fan (I guess we agree on that), that means more start ups and more wear and tear for the compressor. The duration of running cycles won't necessarily be shorter as it depends on air displacement caused by the fan. I would not be surprised if the fan results not only in more often cycles but also longer duration for each cycle, for example (just hypothetically to make a point):

With fan: 10 start ups a day, 30 minutes each
No fan: 8 Start ups a day, 20 minutes each

Do you want bet? Just kidding... But even if the cycles are of longer duration, the use of the fan will reduce the life of the compressor as you know.

 

[Beer_Guy]

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

…
... the electrical energy given to the fan is dissipated as heat inside the kegerator...

Obviously, I'm not the only one here at HBT who thinks that putting a device that actually creates heat inside…will warm it up …

I use one of the 120mm Quiet fans. Less noise and heat, but still enough air movement to do the job.

The idea of a fan inside is to keep the temps even top to bottom. If the fan is not on unless the compressor is on, the warmer air will rise until it fills the top down to the thermostat.

A test could be done by placing your fan inside an empty cooler with a temp probe to find out just how much heat it is putting off. Some of the high air flow ones might get pretty hot. I would bet the 120mm Quiet fans put off VERY little heat.

Plus, where the fan is aimed can reduce the air flow rate needed and improve the effect.

 

[Indyking]

I use one of the 120mm Quiet fans. Less noise and heat, but still enough air movement to do the job.

The idea of a fan inside is to keep the temps even top to bottom. If the fan is not on unless the compressor is on, the warmer air will rise until it fills the top down to the thermostat.

A test could be done by placing your fan inside an empty cooler with a temp probe to find out just how much heat it is putting off. Some of the high air flow ones might get pretty hot. I would bet the 120mm Quiet fans put off VERY little heat.

Plus, where the fan is aimed can reduce the air flow rate needed and improve the effect.

That's a good idea, I think you are talking abot these types of fan:

http://www.amazon.com/dp/B001BMGRMG/?tag=skimlinks_replacement-20

I wonder, how do you power the fan since these usually have those 4 or 3 pin connectors made for computers.

 

[Beer_Guy]

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.

 

[BrewMoreBeers]

It appears that some folks are very concerned with the energy efficiency of running a low voltage computer fan constantly...

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).

I say let the fan rip constantly. With my fan my keezer cycles half as often (temp probe hangs 6 inches down from the lid) and runs for half the time. But, my true cycle/run time savings came from adding insulation to my collar. This is where you will have your big conservation win. Keep you collar air tight and insulate it.

 

[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.