Air movement in keezer

[surreal_trip]

Needed or not? I'm wondering how you gents have gotten the breeze a movin inside your kegerators and keezers... Their's a lot of ideas out there! Lets hear yours!

 

[TomSD]

I noticed a pretty big difference between using one and not. Less compressor time and evener temps.

I use a bilge blower to push the hot air down into the bottom. I also had to lift my kegs off the floor since they were packed so tight there was no circulation.

 

[devilishprune]

I have a simpler setup than that.

Just a computer fan connected to a wall wart blowing warm air down to mix things up. Temperatures are much more even this way, and it keeps my keg on the bottom from freezing.

 

[Catt22]

IMO, definitely needed. I'm using a 110 v AC muffin fan to circulate the air in my converted freezer. I also have fans installed in my fermentation chambers for the same purpose:

Keeps the beer lines and taps cold and the beer at a uniform temperature. I have the temp controller probe mounted in the air stream from the fan and the fan runs continuously. Works very well for me. No more partially frozen kegs or warm, foamy initial pours.

 

[chumprock]

I started to put together some pvc to make something to move my air around in there, and never got around to it and then re-purposed the PVC. I guess I dont notice any existing problems with the amount my compressor runs (hardly ever), or any issues with too cold/warm. I just thought I had to do it because I had read about it here..

I think this goes along with every other aspect of this hobby, you can make it as easy or as complicated as you want, and you'll still have a finished product.

 

[billtzk]

I put a 110 v muffin fan in my keezer, on standoffs under the lid just like the one Cat22 did, except that I wired it into the existing wiring in the lid. It runs continuously and keeps temps even all over the keezer.

 

[92greenyj]

I didn't put one in mine and i've never really noticed any adverse effects from not having one. I also don't think i really have enough room to allow for even air flow between my kegs anyway. they are packed in there pretty tight

 

[shroomzofdoom]

I've noticed some anecdotal observations in my keez both with and without a fan. I have a coffin and a 2x8 insulated collar so air movement is essential.

With no fans or underpowered fans, the compressor would go out about 6-8 times a day for about 1-2 hours each. It now goes on about 10 times a day, but for about 30 minutes each. I would assume this means less stratification and less work by the compressor to remove warmth. This should translate to a slightly lower operating cost.

I have some info on cooling in my sig line as I learned a lot about cooling when trying to do my coffin.

 

[chumprock]

Yeah, I should note that I use towers and not a collar. I could see how cooling loss could be a bigger deal with that.

I dont think my compressor comes on more than 3-4 times a day, and never for more than a few minutes.

 

[Catt22]

With no fans or underpowered fans, the compressor would go out about 6-8 times a day for about 1-2 hours each. It now goes on about 10 times a day, but for about 30 minutes each. I would assume this means less stratification and less work by the compressor to remove warmth. This should translate to a slightly lower operating cost.

My experience with using a fan in a converted freezer has been just the opposite with the compressor running more frequently. I think this is a result of the circulating air cooling the lid, collar and taps and a lot of heat is infiltrating at those points. Without the fan, the cold air tends to pool in the lower portion of the freezer. I have not insulated the 2 x 6 collar, but I plan to do so soon and I think that will help considerably. I've timed the cycles with the fan installed, but not without the fan running. I'll do some more timed testing and report the results.

The planned test runs will be:

1. With fan running continuously and no insulation on the collar
2. Without fan running and no insulation on the collar
3. With fan running continuously and with insulated collar
4. Without fan running and with insulated collar

I'll log the ambient room temperature and the duration of the compressor on/off periods. I haven't decided on what type of insulation to use, but it will probably be the rigid foam stuff.

IMO, with the fan the cooling is much more uniform, but at the expense of the compressor running more and using more power.

 

[Indyking]

The planned test runs will be:

1. With fan running continuously and no insulation on the collar
2. Without fan running and no insulation on the collar
3. With fan running continuously and with insulated collar
4. Without fan running and with insulated collar

I'll log the ambient room temperature and the duration of the compressor on/off periods. I haven't decided on what type of insulation to use, but it will probably be the rigid foam stuff.

IMO, with the fan the cooling is much more uniform, but at the expense of the compressor running more and using more power.

That would be a fantastic experiment. It would be better if you keep the room temperature steady to minimize the influencing variables. If the freezer is in the garage and it can't be moved inside, I'm afraid that temperature oscillation in the garage will have a considerable impact in your results, you will need a huge sampling to compensate that.

I do believe, regardless of presence or absence of collar insulation, that a continuously running fan will always cause the condenser to go off more often.

I think having a fan “always on” is a mistake. If the fan can be wired to the "switch on" source (in the thermostat or controller) and be triggered only when the compressor is running, that would likely reduce the frequency of the compressor being triggered and would still provide the benefits of circulating air inside, which is to keep the lines cool and beer temps more uniform inside the kegs.

 

[shroomzofdoom]

It's a worthy experiment and I think it would be great if it could be scientifically done. As mentioned, my experience is anecdotal. I work from home, about 10 feet from the keez and it's pretty loud when it cycles. For a few days, I jotted down the stats and realized that with a fan, the compressor runs more frequently but for noticably less duration each cycle.

To envision this as similar to a room with a window AC. If you turn the AC on and off during the day, it's much more inefficient than if you let it run all day, providing for minimal cooling inputs during the day. In the on/off cyclce it then has to remove heat from the walls, bedding, etc (dead spots) and work harder when it cycles.

In a keez (esp with a coffin/collar design) those dead spots can get very warm with no air movement. With my setup, turning the fan off is simply not an option. When I do, all the cold air sinks, and warm air rises. The coffin temps go to 50 degrees in minutes with no air recirc.

I applaud the effort to study it. But in my keez the fan will always be on--regardless of the results

 

[Catt22]

That would be a fantastic experiment. It would be better if you keep the room temperature steady to minimize the influencing variables. If the freezer is in the garage and it can't be moved inside, I'm afraid that temperature oscillation in the garage will have a considerable impact in your results, you will need a huge sampling to compensate that.

I do believe, regardless of presence or absence of collar insulation, that a continuously running fan will always cause the condenser to go off more often.

I think having a fan “always on” is a mistake. If the fan can be wired to the "switch on" source (in the thermostat or controller) and be triggered only when the compressor is running, that would likely reduce the frequency of the compressor being triggered and would still provide the benefits of circulating air inside, which is to keep the lines cool and beer temps more uniform inside the kegs.

My serving freezer is in my kitchen and at this time of the year the room temperature is very stable at about 72F. I have a digital indoor/outdoor thermometer sitting right on top of the Johnson controller.

I disagree that having the fan running continuously is a mistake. Granted, I'm convinced that the compressor will run more this way, but the freezer temps will be more uniform. I have two reasons for running the fan continuously. First, the controller sensor is mounted direcetly in the fan air stream. I figure this will provide the fastest response time. Secondly, I want the air temp to be as uniform as possible continuously. As I mentioned previously, IMO this configuration provides better temperature control, but at the expense of more wear and tear on the compressor and increased power consumption. It's definitely a trade off and how best to set it up would depend on whether your priority is the best temperature control or the least power consumption/wear and tear on the compressor etc. I sort of choose a compromise with the fan running continuously, but with the controller differential set to 5 F thinking that a wider differential results in less wear and tear. There are a number of variables and I'm not at all sure of whether it is better to run the compressor longer and at less frequent intervals or to have it run for shorter durations but more frequently. I do know that it's not good to short cycle the compressor, but where the break even point might be I have no clue. Maybe a refrigeration specialist or an engineer versed in this stuff could help out here. I will run the tests as scientifically as I can.

 

[shroomzofdoom]

Where are our HVAC and/or process control guys to settle this?
(Probably all lurking on the electric brewery forum...LOL)

My argument would be that even though the compressor cycles more often with a fan, this air movement makes this more efficient operation...thus shorter compressor cycles.

It may not be cheaper to run as any electric motor requires a lot more power at startup than at continuous operation, but compressor activity is I think the biggest power draw here.

Still, I simply can't run my keez with the fan off, coffin temps go to high and foam ensues...so the point is moot for me.

 

[Indyking]

Right, only a refrigeration engineer or experienced technician could settle this argument, but my observations from other blogs about refrigeration set-ups for camping or RVs suggest that running a fan continuously, even a small computer fan, inside a sealed compartment like a chest freezer is a bad idea. An internal fan will struggle to suck air from every corner and dead space that is not sealed, bringing in heat. In addition, the little motor gets warm trying to find enough air to function and releases heat too. In fact, the reason why the compressor is working more is because it needs more working power to compensate for the heat brought in by the fan. Yes, a continuously running fan will surely keep air well distributed all the time and steady temps for lines and keg, but heck, it will also short your compressor life significantly and considerably increase your energy waste. The benefit of air distribution with a fan inside a freezer is only efficient when the fan is allowed to work for limited periods of time and from what I learned, it can actually be very beneficial in that way.

I think other people here have hooked their internal computer fans to the controller or thermostat for better efficiency.

 

[shroomzofdoom]

Right, only a refrigeration engineer or experienced technician could settle this argument, but my observations from other blogs about refrigeration set-ups for camping or RVs suggest that running a fan continuously, even a small computer fan, inside a sealed compartment like a chest freezer is a bad idea. An internal fan will struggle to suck air from every corner and dead space that is not sealed, bringing in heat. In addition, the little motor gets warm trying to find enough air to function and releases heat too. In fact, the reason why the compressor is working more is because it needs more working power to compensate for the heat brought in by the fan. Yes, a continuously running fan will surely keep air well distributed all the time and steady temps for lines and keg, but heck, it will also short your compressor life significantly and considerably increase your energy waste. The benefit of air distribution with a fan inside a freezer is only efficient when the fan is allowed to work for limited periods of time and from what I learned, it can actually be very beneficial in that way.

I think other people here have hooked their internal computer fans to the controller or thermostat for better efficiency.

I am sorry but I have to ask...do you have a keezer and are speaking from experience, or are you referring to hearsay from other forums? I read dozens of keezer threads here, and I don't know of any that successfully have their fan cycling on and off. If I am mistaken, please find us some examples from HBT.

I don't mean to sound like a tool, but only real world experience or actual scientific analysis is going to answer this type of question...anything else is just fud.

 

[TomSD]

Sucking air from... huh? It is circulating the air that is already there. The intent is to keep the warm air in the top/collar circulating with the colder air in the bottom. There is no strain to find air or suction from any gaps in your insulation. It is moving the air around inside it is not displacing air.

 

[Catt22]

My argument would be that even though the compressor cycles more often with a fan, this air movement makes this more efficient operation...thus shorter compressor cycles.

It may not be cheaper to run as any electric motor requires a lot more power at startup than at continuous operation, but compressor activity is I think the biggest power draw here.

Still, I simply can't run my keez with the fan off, coffin temps go to high and foam ensues...so the point is moot for me.

IIRC, most of the wear on the compressor happens at start up, so more frequent cycling probably shortens the life of the freezer somewhat. My taps get too warm in hot weather without the fan running continuously.

 

[Catt22]

Right, only a refrigeration engineer or experienced technician could settle this argument, but my observations from other blogs about refrigeration set-ups for camping or RVs suggest that running a fan continuously, even a small computer fan, inside a sealed compartment like a chest freezer is a bad idea. An internal fan will struggle to suck air from every corner and dead space that is not sealed, bringing in heat. In addition, the little motor gets warm trying to find enough air to function and releases heat too. In fact, the reason why the compressor is working more is because it needs more working power to compensate for the heat brought in by the fan. Yes, a continuously running fan will surely keep air well distributed all the time and steady temps for lines and keg, but heck, it will also short your compressor life significantly and considerably increase your energy waste. The benefit of air distribution with a fan inside a freezer is only efficient when the fan is allowed to work for limited periods of time and from what I learned, it can actually be very beneficial in that way.

I think other people here have hooked their internal computer fans to the controller or thermostat for better efficiency.

The fan I use doesn't seem to struggle at all. It certainly must generate some heat, but I think only a very trivial amount. I agree that running a fan continuously is inherently less efficient, but efficiency for me is secondary to uniform temperature in the freezer. I think I said that earlier. It's a trade off and in my case a compromise to some degree.

 

[Indyking]

I am sorry but I have to ask...do you have a keezer and are speaking from experience, or are you referring to hearsay from other forums? I read dozens of keezer threads here, and I don't know of any that successfully have their fan cycling on and off. If I am mistaken, please find us some examples from HBT.

I don't mean to sound like a tool, but only real world experience or actual scientific analysis is going to answer this type of question...anything else is just fud.

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:

The Love controller provides switched power on the green wire which is connected by a yellow wire nut to the compressor and to the last prong on the wall bug. This allows the fan to run when the compressor runs, and stop when the compressor stops. I like this rather than having it run all the time because the electrical energy given to the fan is dissipated as heat inside the kegerator, making it less efficient.

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.

 

[shroomzofdoom]

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

He may have a good looking keez, but both Love and Johnson advise keeping their probes out of water. Sometimes, things works in spite of their design...not because of it.

If we are using fans to break up stratification...Then why allow the keezer to become stratified at all? In other words, why cycle the fan OFF when the compressor is OFF? To save from heat buildup? I just don't think it's a concern in a forty degree space with gallons of cold beer, metal, etc.

 

[Indyking]

He may have a good looking keez, but both Love and Johnson advise keeping their probes out of water. Sometimes, things works in spite of their design...not because of it.

If we are using fans to break up stratification...Then why allow the keezer to become stratified at all? In other words, why cycle the fan OFF when the compressor is OFF? To save from heat buildup? I just don't think it's a concern in a forty degree space with gallons of cold beer, metal, etc.

The subject of probe in the water is also debatable... manufacturers recommend to leave them out of water to simply avoid damage, but on that respect, I actually know from experience that the Love prove will not damage if kept under water. Just like there is no question a fan inside a freezer will generate unwanted heat that needs more compressor work to be compensated, a probe outside water will capture greater temperature fluctuations when exposed to outside air (when door is opened) and make your keezer work more to compensate.

Sometimes I even question what the usefulness of a fan for air distribution inside a keezer is at all, since none of the folks at my LHBS actually have a fan in theirs. They claim the room inside is crowed enough with kegs, bottles, tanks, and lines that there isn't really much space for air circulation. None of them have ever had any issue with frozen lines or warm pockets of beer but they do a very good job insulating their collars.

 

[Hang Glider]

The subject of probe in the water is also debatable... manufacturers recommend to leave them out of water to simply avoid damage, but on that respect, I actually know from experience that the Love prove will not damage if kept under water...

SOME Love probes maybe. Mine died after a few months - I got an error code, I called Dwyer - they said "Probe Error."
So now I slide them into a sleeve of hobby-shop brass, epoxy the ends, and I'm golden.

 

[Indyking]

SOME Love probes maybe. Mine died after a few months - I got an error code, I called Dwyer - they said "Probe Error."
So now I slide them into a sleeve of hobby-shop brass, epoxy the ends, and I'm golden.

I guess people I know and myself have had better luck...

 

[Catt22]

If we are using fans to break up stratification...Then why allow the keezer to become stratified at all? In other words, why cycle the fan OFF when the compressor is OFF? To save from heat buildup? I just don't think it's a concern in a forty degree space with gallons of cold beer, metal, etc.

I agree. Seems counterproductive to set it up to increase the temperature stratification when the desired effect is just the opposite. The heat generated by a muffin fan is negligible IMO. Mine doesn't even get warm to the touch when run outside of the freezer. Sure, it's an electric motor and it will generate some heat, but we're talking about a very, very tiny amount of heat. Relative to the heat infiltrating a freezer it's not even worth considering and I doubt you would be able to even measure the difference without some highly sophisticated test equipment.

IMO, putting a temp probe in a container of water is not the way to go. All it will do is increase the controller response time and widen the temperature swings. You could do the same by simply setting the controller differential higher.

I picked up the insulation for the collar today. I bought the 3/4" polystyrene foam without the foil backing. It should help immensely with the heat gain through the collar. It may be several days before I can get the testing done, but stay tuned for further developments.

 

[billtzk]

My love probe is in water. ( Hmmm) I didn't know that wasn't recommended by Dwyer. I may encase it in something to protect it like Hang Glider did. Before I put it in water, the temperature swings occurred more rapidly causing the compressor to cycle more frequently.

But I'm still experimenting to find the best setup. My controller hysteresis is set to 3 degrees. I think that setting it to 5 degrees would reduce compressor cycling frequency but cause the compressor to run longer. That might actually be more desirable from both an energy consumption perspective and compressor service life. I don't like the idea of my beer temperature changing that much though.

I have not yet insulated my collar. I really like the hangar bolts that Quaffer used to hang his manifolds. He's got a few other good ideas in that thread too.

 

[Indyking]

My love probe is in water. ( Hmmm) I didn't know that wasn't recommended by Dwyer. I may encase it in something to protect it like Hang Glider did. Before I put it in water, the temperature swings occurred more rapidly causing the compressor to cycle more frequently.

But I'm still experimenting to find the best setup. My controller hysteresis is set to 3 degrees. I think that setting it to 5 degrees would reduce compressor cycling frequency but cause the compressor to run longer. That might actually be more desirable from both an energy consumption perspective and compressor service life. I don't like the idea of my beer temperature changing that much though.

I have not yet insulated my collar. I really like the hangar bolts that Quaffer used to hang his manifolds. He's got a few other good ideas in that thread too.

The folks in my LHBS all use their Love thermistor probes inside water, for years now and never had any problems. Like you said, it avoid temperatures swings since the hot air coming in when you open the keezer door don't affect the water temperature much. That saves you compressor work, i.e. less energy waste and more life time for the compressor.

 

[Indyking]

I agree. Seems counterproductive to set it up to increase the temperature stratification when the desired effect is just the opposite. The heat generated by a muffin fan is negligible IMO. Mine doesn't even get warm to the touch when run outside of the freezer. Sure, it's an electric motor and it will generate some heat, but we're talking about a very, very tiny amount of heat. Relative to the heat infiltrating a freezer it's not even worth considering and I doubt you would be able to even measure the difference without some highly sophisticated test equipment.

IMO, putting a temp probe in a container of water is not the way to go. All it will do is increase the controller response time and widen the temperature swings. You could do the same by simply setting the controller differential higher.

I picked up the insulation for the collar today. I bought the 3/4" polystyrene foam without the foil backing. It should help immensely with the heat gain through the collar. It may be several days before I can get the testing done, but stay tuned for further developments.

So, how do you plan to measure air distribution or temperature distribution throughout different parts of the keezer in your experiment? Isn't the whole point of having a fan running continuously about improving air distribution and assure even distribution of temperature for lines and keg at the expense of more compressor work? I mean, just measuring how many times or duration of compressor cycles with or without the fan is not going to tell much, am I wrong? I guess it would be good put some numbers to prove facts we already know.

 

[Catt22]

Like you said, it avoid temperatures swings since the hot air coming in when you open the keezer door don't affect the water temperature much. That saves you compressor work, i.e. less energy waste and more life time for the compressor.

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.

 

[Catt22]

So, how do you plan to measure air distribution or temperature distribution throughout different parts of the keezer in your experiment? Isn't the whole point of having a fan running continuously about improving air distribution and assure even distribution of temperature for lines and keg at the expense of more compressor work? I mean, just measuring how many times or duration of compressor cycles with or without the fan is not going to tell much, am I wrong? I guess it would be good put some numbers to prove facts we already know.

I don't plan to measure the temperature of the air distribution at all right now. The controller probe is mounted near the top lip of the freezer wall, in the center and in the air stream of the fan (when the fan is in operation, that is). It will be in the same position for all tests. Instead, I will measure the temperature of beer poured from four kegs through four different taps.

I will be logging the cycle times and the duration of the on/off periods. This will yield the percent run time per cycle. Additionally, I will have a kill-a-watt meter hooked up and this will record the watt hour power consumption per cycle. I will run the tests at least 24 hours apart to allow time for the temps to equalize for the various configurations. Obviously, this testing won't be applicable to other setups as such things as where the probe is placed, the size of the freezer, how many kegs and how full they are will influence the data. The main objective is to see how the fan affects the cycle times and power consumption and the same for insulating the collar. I'm not out to prove anything one way or the other as I really don't give a damn how anyone else sets up their system. I'm doing it out more out of curiosity than anything else. Some may find the information useful and others may not. Either way is just fine with me.