Yuri Brewclost -> KegerAC Will the compressor fail?

[GuateBrewer]

So I have been shopping around for a decent chest freezer or large fridge to get a decent sized Kegerator unit.

I am thinking I would want 6 taps 4 for beer, plus coke and mineral water.

People here in Guatemala do not like to spend money on electricity so there is nothing big enough to suit my needs locally.

So I was thinking to build a mega unit based on the Yuri's work with the fermentation chamber, he claimed he was able to get 30 degree delta with his 5000BTU window unit so I was looking at building something like that but horizontally, and if space permits, even build a special fermentation chamber on one side, with a separate temperature controller running a fan or two.

I am thinking the window unit blowing inside of the unit will keep the condensate under control and be a cost effective way of building a large unit. Its pretty much never colder than 55 and never hotter than 75 here year round. My home HVAC system is open and close windows so waste heat indoors is not an issue, nor is it an issue if I put it in my covered garden area (pending approval).

However my question is my friend who knows it all claims that if I run the AC unit recirculating cold air to attempt to be in the mid 40's instead of the mid 70's it is normally used for I will encounter problems with the pressure of the gas, freezing of the coils etc? Does this make any since that running the unit colder than it was engineered for will completely fail, or will it just be a bit less effective?

Anyone ever tried anything like this?

Thanks!!

 

[McKBrew]

This whole thread below is interesting, and a portion of it describes how to re-wire an Air Conditioner to cool at lower temperatures.

https://www.homebrewtalk.com/showthread.php?t=11440&page=1

If you don't want to read the whole thing, this part gets into the re-wiring part a little quicker.

http://franklinbrew.org/members/sj/walkin.html

 

[processhead]

I can't speak from personal experience, but a while back I did some reading up on using a window a/c unit to build a walk-in cooler.
I heard that the freezing coil can be an issue in high humidity areas, as well as a requirement that the thermostat sensor of the AC unit needs to be relocated remotely from the unit.
There is a guy selling specialized controllers for building these walk in coolers.
Try Googling "home made walk in cooler"

 

[Yuri_Rage]

I heard that the freezing coil can be an issue in high humidity areas.

You took the words right out of my mouth! When trying to maintain very low temps (40° F or less), the coils easily freeze condensate over them, and the unit becomes extremely inefficient, eventually becoming ineffective. I think one possible solution is to use an A/C unit that is well oversized for the application. I've yet to successfully maintain anything lower than 50° F for longer than a few hours with my rig. I gave up on lagering until I can upgrade to a more efficient setup.

 

[Funkenjaeger]

Just thought I'd throw this one out there:
http://www.mrmalty.com/brewstuff.php
Look about 2/3 of the way down.

 

[GuateBrewer]

Originally Posted by processhead
I heard that the freezing coil can be an issue in high humidity areas

Looks like we have a few threads where it has worked, and I have the controllers, however, I am pretty certain in the rainy season when the humidity is so high that without a dehumidfier in the closet, all your clothes and stuff MOLDS, that I would fall victim to the freeze up that my friend is talking about and that Yuri is bumping into.

Well back to the drawing board, with my money still in my pocket at least

 

[Yuri_Rage]

the freeze up that my friend is talking about and that Yuri is bumping into

BTW, average humidity here is less than 20%...

 

[John Beere]

Here is my walk-in cooler thread built on a 10k btu window a/c. I live in a very high humidity area and have taken extra steps to keep the coils from freezing. I keep it year round at 35 degrees...

This was published last year in Zymurgy - PM me if you would like a copy.

**EDIT** fixed the link...

 

[GuateBrewer]

Yeah I was just reading something about certain AC units having a thermostat mounted to the evaporater coil to prevent the temperature of the unit from dropping below freezing, just looking at some the the home improvement stores to see if I can find a decent sized unit which has that feature and then see if I can source it locally.

Might not be a dead deal after all.

Damn slick setup you have there

Thanks!!

 

[RadicalEd]

FYI John, your link is slightly broken. Here's a working one!

Guate, definitely give John's thread a good, long read. I read through it some time back and while I don't remember the details, it was quite excellently done.

Outside of thermostat and condensation issues, I can firmly say running your unit like this should not greatly negatively affect your unit's lifespan. In many ways, it is in no way different than the way your refrigerator runs; it just looks a wee different. Computer cooling is another hobby of mine, so I got into HVAC a little; I know guys that cool liquid down to -20*C with relatively unmodded air conditioners for extended periods of time; running your unit as a refrigerator should be a walk in the park!

My best advice is to make sure you get good airflow over both the evaporator (cold side) and condenser (hot side) coils.

 

[kladue]

A couple of suggestions for cold rooms and cooling units, moisture flows from the warm areas into the cooler areas, so put your vapor barrier on the outside of the cooler structure. Room air conditioners will work for a while if you seal up any and all holes that let outside air into the cold side of the airconditioner to limit the amount of moisture it has to condense inside the cooler. The lower the moisture condensation inside the cooler the easier it is on the cooling unit operation. Another concern is oversizing the cooling unit and killing it by short cycling the compressor, bigger is not always better.

 

[John Beere]

Look at post #152 on page 6 of my thread. You can see ice buildup on the coils in the second photo. Hooking those fans up which run 24/7 has completely eliminated any moisture build-up on the coils, regardless of the amount of moisture inside the cooler.

 

[GuateBrewer]

Yeah I spent about an hour reading though the other thread last night as well as the link to the website of the other walk-in cooler, it almost looks like the biggest difference between those two projects and Yuri's project is a boatload of insulation as well as having everything as air tight as it is possible, I was looking/pricing out something more along the Yuri solution of a few tubes of caulk a few sheets of plywood and a few sheets of board insulation.

I have also noticed that both of the working solutions either have the fan rigged to run full time, or a secondary fan rigged to run when the unit is off to pull cool air over the cold coils I assume to pull moisture out of the air, and also to get the coils above freezing as soon as possible if the unit does not have freeze protection.

As far as liquid chilling for computers this brings up an idea, use the AC unit to chill a glycol or brine mix, and then circulate that mix though two or more heat exchangers, assuming I am below freezing, with the warmest/wettest air hitting the warmest flow of coolant, and then passing to the coldest below freezing heat exchanger.

But alas, recirc pumps, some automotive heater cores and all that are not practically free here like the US, so perhaps I am just better off throwing something of the box in a container and bringing it down.


Right now I am a bit torn on this project, on one side if it works - great then I get exactly what I want sooner and cheaper - if it does not work I have a few hundred
dollars invested in parts....and have to wait even longer and invest more funds to get where I am trying to go - I guess this is the true with all DIY solutions.

Ahhgg - All I really want is cold beer!

 

[RadicalEd]

Hahahaha, don't worry, there's nothing magic about these systems. They just require a little thoughtful planning and advice.

Personally I wouldn't bother with recirculating glycol; it will just move the cold interface surface to a new location (the heat exchanger) and you'll still have the same frost issues.

A little insulation, an A/C, a temp controller, and a fan. Not too much more to it! I know, I know, easier said than done .

 

[olllllo]

I was thinking of the ice making in the Mosquito Coast the entire time I was reading this thread.