I have constructed a keg cabinet as part of my bar in my basement and am trying to figure out how much refrigeration I need to keep my kegs cool. The cabinet measures 27" H x 40" W x 24" D and has 1.5" of pink Styrofoam insulation board on all sides. I read Chris Bible’s article in this month’s BYO and calculated that I need about 400 BTU/Hr to keep the interior at about 35 deg F with an exterior temperature of about 75 deg F but this seems like a low number. Can anyone tell me if this value is in the right ball park? Also, I am trying to decide whether to use conventional refrigeration or thermoelectric. For conventional, I am looking at a remote condenser unit off to the side with an evaporator inside the cabinet. A thermoelectric unit could be mounted directly to the side of the cabinet. Any thoughts on pros and cons of each type of system? Can anyone suggest a unit that can provide the level of cooling that I need at the above temperatures.
I’m all for using a TEC system, but my experiences with them have been mixed. Cools well but keeping a stable temp was problematic. Zymurgy has the article about the Ghettochill 9000 with two TECS and a power supply.
Yes, I read the article in Zymurgy as well and went back and read the article on the Gettochill 5000 in last year’s gadgets issue but I didn’t see any info on how to choose a unit of the correct size. I did a little research on thermoelectric units and it looks like they become less and less efficient the larger the temperature differential you are trying to achieve. If I was interpreting the information correctly, I looked like I would need a 1500 BTU unit to pump 400 BTU/Hr at a 40 deg F differential.
Not much help with your engineering issue, but I did notice you said 35º…IMHO waaaayyyy too cold. 45 is the highest I can set my keggerator, and it would be on 50º if I could. Cold kills flavor.
I looked online and found that the R value for the foam ranges between 4 and 8 per inch of insulation so I used a value of 4.
I know that 35 is colder than I really want to keep my beer but I want some factor of safety so the unit wont have to run all the time. The cabinet is actually devided into two compartments and I want to be able to keep my lagers and lighter ales at about 40 deg in one compartment and my heavier ales at about 50 deg in the other. I plan to use thermostaticaly controlled fans to draw cold air from the colder compartment to the warmer. I just want to make sure that, if anything, I have more refrigeration than I need rather than less.
OK, so the area is 274024 = 25920 in^2 = 180 ft^2. Going with an r-value of 4.0 ft^2-°F-hr/BTU-in: (180 ft^2)(40°F)/(1.5 in)(4.0 ft^2-°F-hr/BTU-in) = 1200 BTU/hr.
Sorry. I’m new to this forum stuff so I don’t know how to quote who I’m responding to but 249 BTU/hr is the same number I got. I just thought I might me plugging in a number in with the wrong units somewhere. I bumped it up to 400 to account for leakage and so the unit wouldn’t have to run all the time. Since we’re all coming up with the same number, what I need to know now is what kind of refrigeration unit I need to provide that rate of cooling. I’ve looked at a unit designed for boats manufactured by Mermaid, the MM2 remote refrigeration unit with their 425M evaporator, but I didn’t see a BTU rating on their web page. I’ve also looked at a 1/4 HP Embraco condensing unit which is rated at 3650 BTU [u]http://www.globalindustrial.com/p/hvac/compressors-line-filter-dryers/compressors/embraco-condensing-unit[/u] but that seems like way more than I need. I also found a Dayton unit (CU102 Commercial Temperature Air Condensing Unit) [u]http://www.daytonrefrigeration.com/servlet/the-163/dayton-refrigeration%2C-refrigeration-parts%2C/Detail[/u] but again the BTU rating seems way more than I need. What I’m not sure of is how the rated capacity applies at the temperature differential that I am looking for, especially after discovering how much the TEC units drop off with temperature differential. I’m hoping someone with some refrigeration experience and/or knowledge can give me some guidance on how large a unit I need to pump 400 BTU per hour at a 40 deg F differential. I would prefer a TEC unit because of he simplicity of installation but the efficiency issue may make that unfiesable. Any guidance would be greatly appreciated.
I know people have done something similar to what you want, although on a larger scale, using a window air conditioner. That might be the cheapest and/or easiest option. Any commercial unit should be overkill for what you need.
