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Old 06-03-2010, 05:40 PM   #1
JayInJersey
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For those of you that use an A/C Window unit for the cooling of your Ferm Chamber, how cool can you get it?


I ask as I'm considering using one on a chamber I plan to build in my garage but my window unit has its own temp gauge and only goes to 60*.

And if I figure on the average of a 5* change from ambient to brew it would only be able to cool to roughly 65*...which will probably be fine, but I'd love to be able to pull off a 62/3 now and then.


And while I've got you here...how do you bypass the units internal thermostat anyway? I get how you would do it in a fridge...but the A?C unit never seems to blow cool air right when it kicks on.
Perhaps just set it to the lowest (60* in my case), mount it at the top of the cabinet and let the whole hot air rising and the internal controls handle it?
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Old 06-03-2010, 06:22 PM   #2
jordanpace
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maybe this website will help...

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


you could go that route or even open the front side of your AC (depending on brand and design of course) and look for the thermostat probe. See if you can re-route that probe to the outside of your fermchamber.

That way the AC is getting readings outside the chamber and you can use an external controller
http://morebeer.com/view_product/166...ure_Controller
to keep it at whatever desired temp you want. (Provided that the outside temp is warmer than 60F)

 
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Old 06-03-2010, 06:27 PM   #3
chrispykid
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No experience with these builds, but my thought would be to get a ranco/johnson/ebay tempertature controller and set it at your target temperature. Then all you need to do is find the air conditioner's built in probe and mount it outside your chamber. This way it'll keep running until your controller tells it to shut down (provided the temperature outside the chamber is higher than the chamber).

Others here might have more elegant solutions for disabling the thermostat entirely.

 
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Old 06-03-2010, 06:28 PM   #4
chrispykid
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Quote:
you could go that route or even open the front side of your AC (depending on brand and design of course) and look for the thermostat probe. See if you can re-route that probe to the outside of your fermchamber.
Man, I need to start typing faster.

 
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Old 06-03-2010, 06:59 PM   #5
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I have a 5000 BTU unit in the brewery and can chill the entire 12x16 space to 50F. It has a built-in digital thermostat and the constant air/intermittent cooling can keep the room within a 2F band when the outside temperature swings 40+ degrees.
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Old 06-03-2010, 07:20 PM   #6
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It if an analog unit, it is realtively easy to find where the thermostat lead goes into the on/off switch. I took a smal piece of copper and simply inserted it into the place where the therm probe used to be. This in essence will make the AC run continuously when it is on. Then I plug the AC into a controller. For some reason my RANCO will not work with it - only the Johnson- not sure why...

If you have one of the AC's that is digital/circuit board controlled, good luck - I tried and have no clue how to disable it.

 
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Old 06-03-2010, 07:59 PM   #7
JayInJersey
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That's impressive david. The unit I hoped to use is 6500 BTUs and the space would only be at max like 4'x3'...I might give it a go and see what happens.

If it doesn't work I'll only be out the cost of the wood...and the insulation...on second thought

 
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Old 06-03-2010, 08:15 PM   #8
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I was given a 5k window AC unit and built an insulated wooden box around it - big enough for about 5 carboys - I rewired the compressor to toggle on/off with an auber instruments temp. controller + SSR - I've got it holding 50 deg. for a lager I'm fermenting right now. it has no problem getting down into the mid 30's.. I've never tried pushing it lower than that.
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Old 06-03-2010, 08:21 PM   #9
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the link is for my 4x7 walkin that I keep at 38 degrees with a tiny AC unit. I lager in it but mostly use it for bottle storage and it holds the kegs from which I run lines to the bar from. I also have three ferm fridges that I use for fermenting. Two are on regular temp controllers and the third is geri-rigged with two thermostats. One controls the fridge and the second controls a plug within the fridge that I can then plug a heating pad into so I can control temp up or down. I can lager in that fridge but then also ramp up temp with the heating pad to mid-high 80's for things like saisons.


http://www.homebrewtalk.com/gallery/...l&ppuser=20497
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Old 06-03-2010, 08:24 PM   #10
Cape Brewing
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Quote:
Originally Posted by JayInJersey View Post
That's impressive david. The unit I hoped to use is 6500 BTUs and the space would only be at max like 4'x3'...I might give it a go and see what happens.

If it doesn't work I'll only be out the cost of the wood...and the insulation...on second thought
You'll make ice with that many BTU's in that small of a space... assuming the coils don't freeze up on the unit first.

If you're going to do ANYTHING with an AC unit, you need to REALLY make sure the vapor barrier is heavy duty (I wrapped my entire walkin with 6mm plastic) or the AC unit will suck humidity right through the wood and your unit will freeze up on you constantly.
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