Coffin cooling question...

[SmokingDog]

Still undecided about how to cool the coffin part of my keezer.

I've purchased a couple of fans, a 4" (with dryer hose) to draw cold air up from the bottom of the freezer and a 3" to return back into the chest.

Has anyone just cut a hole in the lid to match the inside size of the coffin? Essentially, make the chest and the coffin one cavity. Just one fan circulating the cold air all the way around.

 

[skibumdc]

Yes people have done that, but the few I saw eventually put so much insulation into the coffin area that it essentially created a small channel for beer lines and air movement.

 

[bcgpete]

it essentially created a small channel for beer lines and air movement.

This.
You want a path for the air to follow. Just having a large cavity, you will have temperature differences between the bottom of the keezer and the top of the coffin, even with fans moving air. Two holes in the coffin with a fan in one and the lines in the other force the air to circulate through the coffin, which is what you need.

 

[kegtoe]

Just curious, but what is the reasoning for cooling the coffin? I see just about everyone doing this. I have no cooling to mine and have been running it for 1.5 years.

 

[bcgpete]

Just curious, but what is the reasoning for cooling the coffin? I see just about everyone doing this. I have no cooling to mine and have been running it for 1.5 years.

You want your beer lines to be as uniform in temperature as possible. Change in temperature as the beer flows through the lines means change in pressure means change in concentration of CO2.

Generally the problem is that the coffin is warmer than the keg, so as the beer flows through the coffin it warms up, causing it to hold less CO2 in solution, in turn making your pour quite foamy.

 

[Pumpkinman906]

Just curious, but what is the reasoning for cooling the coffin? I see just about everyone doing this. I have no cooling to mine and have been running it for 1.5 years.

I see the theory in cooling the coffin, but lets think about this logically for a second. The volume of beer that is exposed to any temperature differential is
significantly smaller than the rest of the balanced run inside the fridge/keezer. Additionally, the amount of time that small proportion of product is exposed to the temperature differential is fractional. Therefore, would it not be logical to deduce that while in theory, warmer product has the capacity to hold less CO2 within than does colder product, the reality is the amount of product and the time the product is exposed to any slightly higher temperature in the coffin will have minimal, if any effect during a pour. Any product sitting in the line between pours is also minimal as compared to a full pint and is quickly displaced by the colder product of much higher volume, again, minimizing any theoretical foam issues.
In summary, if ya got foam, your system isn't balanced. It's not your beer is running through a 100 foot greenhouse that is 120 degrees...Its 8" of 1/4" line for less than a second.

 

[Markd27]

Just curious, but what is the reasoning for cooling the coffin? I see just about everyone doing this. I have no cooling to mine and have been running it for 1.5 years.

Edit: I see the point of cooling it, I just don't see the point of sealing if off separate from the rest of the keezer. Just cut the bottom open, and drop a fan in below to direct air upwards. Sealing it off, insulating it, creating an air channel and all that just always seemed counterintuitive to me.

 

[kegtoe]

yikes. if i'm only drinking 1 beer, i grab a bottle from the fridge. if i'm have a few from the keezer i pour about 2 ounces into a cup and throw that - lines and tap are now chilled and good for the night. I usually dont like the first ounce or two anyway as it may be stale

 

[JuanMoore]

I see the theory in cooling the coffin, but lets think about this logically for a second. The volume of beer that is exposed to any temperature differential is
significantly smaller than the rest of the balanced run inside the fridge/keezer. Additionally, the amount of time that small proportion of product is exposed to the temperature differential is fractional. Therefore, would it not be logical to deduce that while in theory, warmer product has the capacity to hold less CO2 within than does colder product, the reality is the amount of product and the time the product is exposed to any slightly higher temperature in the coffin will have minimal, if any effect during a pour. Any product sitting in the line between pours is also minimal as compared to a full pint and is quickly displaced by the colder product of much higher volume, again, minimizing any theoretical foam issues.
In summary, if ya got foam, your system isn't balanced. It's not your beer is running through a 100 foot greenhouse that is 120 degrees...Its 8" of 1/4" line for less than a second.

Even in a well balanced system the first several oz of the day will be foamy if the faucet and shank are significantly warmer than the beer. The thing you may be failing to take into account is the thermal mass of the shank. Cooling the coffin or tower is actually more about keeping the shank cool than the beer lines.

Many people (like kegtoe above) simply dump the first few oz down the drain at the start of every drinking session. Others take measures to keep the lines and shanks cool instead. I used to just live with a warm tower, but I have a lot of people come over wanting a sample of each beer I have on tap at any given time. After a while of pouring off a few oz from each of my faucets every time, it seemed wasteful and a bit of a PITA, so I added a fan. As always, YMMV.

 

[Kyled93]

Just so I can understand, what does this coffin look like? If it is what I am thinking why us a fan? Why not use a small bucket of water/food grade glycol , and submersible pump to recirculate around the faucet and beer line. This would seem like a simpler task than trying to run a fan and dryer vent line and the process should be more efficient . I could be wrong as what I am picturing in my head may not be what is being discussed, hence need a photo. Lol cheers.

 

[Hoppopotomus]

I agree with JuanMoore....the thermal mass of a 4 or 5 inch steel shank kept at a significantly higher temperature than the serving temperature of the beer is a big culprit of CO2 coming out of solution causing foaming issues. I have two 4" inductor fans, an intake to draw cold air up out of the freezer and an exhaust to return air back down into the freezer for re-cooling. I created a channel for the air flow within rigid foam insualtion that fills the entire cavity of the coffin, so that the air travels up through the intake (the beer lines come through the lid through a seperate port and merge into the intake channel), across the shank cavity, and back down to the freezer. With the entire cavity of the coffin filled with insulation and a small air channel, I am able to stabilize my coffin temps and keep my lines/shanks within a 5 to 8 degree differential from beer temps. I also incorporated a dual input/dual output Love controller (TSS2), so that I can control the keezer temperature and the coffin temperatures independent of one another. This was not a terribly complicated process and it does a hell of a job at keeping the lines/shanks cold. In fact, my Perlicks are frigid to the touch at all times. No foaming issues whatsoever, but I have worked a lot on balancing the system as well.

 

[JuanMoore]

Just so I can understand, what does this coffin look like? If it is what I am thinking why us a fan? Why not use a small bucket of water/food grade glycol , and submersible pump to recirculate around the faucet and beer line. This would seem like a simpler task than trying to run a fan and dryer vent line and the process should be more efficient . I could be wrong as what I am picturing in my head may not be what is being discussed, hence need a photo. Lol cheers.

Here's some examples of coffin boxes- https://www.homebrewtalk.com/f51/coffin-keezer-list-256871/

Some people do recirculate water/saltwater/glycol solutions through a cooling loop, and it's particularly common for larger commercial systems or long draw systems. IMO a muffin fan or two is a much cheaper and easier solution for smaller runs and keezer coffin boxes, and also takes up much less space. I'm not sure, but I'd imagine a muffin fan draws less than a pump, so it's likely more efficient also. For long runs or large pass-through towers with limited space for airflow, a cooling loop is probably the better choice.

 

[carlisle_bob]

Hi

If you cut a big hole in the top of the freezer / bottom of the tower you may compromise the structure a bit. A lot depends on just how things are built now. A couple of holes and fans works pretty well. Once you get the shanks / faucets down to the point humidity condenses out on them, they are not going much lower. Thermodynamics is nasty that way...

Bob