cold box

jward · Post by **jward** » Mon Nov 03, 2008 11:54 pm

I'm building a new larger cold box that uses an air conditioner as a cold source. The box is made from polyisocyanurate a rigid foam board with foil lining. The AC unit will mount on top. The issue is that the open side where the door is lacks the strength to hold the AC unit. Weill it will bow the material too much even if it doesn't break it. I was considering using a wood frame at the top or angle aluminum or steal. Any bright ideas? I'll try to post photos.

backyard brewer · Post by **backyard brewer** » Tue Nov 04, 2008 2:25 am

Like we talked about, I'd use angle aluminum because of the reduced volume compared to wood. You might even be able to embed the cross braces in the walls to support the thing.

jward · Post by **jward** » Wed Nov 12, 2008 9:18 am

Where's a good place to get aluminum angle? Lowes and Home Depot want too much. There's gotta be a welding or metal supply in Santa Ana or otherwise not too farr that's better. So Cal Doug recommended a supplier in Riverside for SS, but that getting kinda out there from Irvine.

backyard brewer · Post by **backyard brewer** » Wed Nov 12, 2008 10:15 am

What size do you need, how much and how soon?

dhempy · Post by **dhempy** » Wed Nov 12, 2008 10:18 am

Why can't you put the AC unit on the bottom and redirect the air? I'm planning on building a box to use refrigerator parts .. the compressor and heavy stuff will sit underneath the lighter insulation material.

As for metals, up here there is a place called Industrial Metals (it is in Sun Valley). Just checked their website ... they have a location in Irvine! Check 'em out!

Dan

backyard brewer · Post by **backyard brewer** » Wed Nov 12, 2008 10:47 am

dhempy wrote:Why can't you put the AC unit on the bottom and redirect the air? I'm planning on building a box to use refrigerator parts .. the compressor and heavy stuff will sit underneath the lighter insulation material.

As for metals, up here there is a place called Industrial Metals (it is in Sun Valley). Just checked their website ... they have a location in Irvine! Check 'em out!

Dan

Probably not a bad idea. You could build a melanine box for the A/C unit and to sit the fermenter on and then build the strofoam box around it. IMS is where I bought my SS.

dhempy · Post by **dhempy** » Wed Nov 12, 2008 11:24 am

Backyard Brewer wrote: Probably not a bad idea. You could build a melamine box for the A/C unit and to sit the fermenter on and then build the styrofoam box around it. IMS is where I bought my SS.

So your contact is at IMS? Cool.

Dan

backyard brewer · Post by **backyard brewer** » Wed Nov 12, 2008 3:29 pm

Steve's contact really. I need to see how this plays out. When I was deciding what to build it out of, Steve just put me in direct contact with the guy and although he was helpful, I really got the impression I was annoying him.

Hopefully I can get another buy because I'm going to need sheet metal for heat shields.

jward · Post by **jward** » Wed Nov 12, 2008 4:54 pm

Backyard Brewer wrote:What size do you need, how much and how soon?

I don't know what size. It should be fairly ridgid over a 45" span. I would need 2 pieces the width of the box about 45" (I need to measure since I just using my memory at the moment). 2 pieces the width of the AC unit 17-18" and 2 pieces to spread the weight across the sides 24" . That's about 16ft with some waste. I should have finished this when you removed the controller. I would buy the materials now if I could. However if I cast the overhead design in stone I can add the opening and build the other parts now and put them together when I get the angles.

dhempy wrote:Why can't you put the AC unit on the bottom and redirect the air? I'm planning on building a box to use refrigerator parts .. the compressor and heavy stuff will sit underneath the lighter insulation material.

I'll have to think about this a bit more. My initial thinking is that the AC unit is lighter then the fermenter and other contents so I'd have to strengthen the bottom considerably to hold contents. Also, the bottom would need openings for the air. That would mean lots of void space on the bottom or some perforated false bottom. If I set the AC on the floor with a side opening I avoid all of those issues but have a larger foot print. Maybe I'm not thinking about this correctly?

dhempy · Post by **dhempy** » Wed Nov 12, 2008 6:28 pm

What I was thinking was perhaps a bit simpler but maybe not.

Start with a plywood platform (on wheels) and sit the AC unit on that. Build another platform over the top of the AC unit just sitting on 2x4s. 3/4" ply should be plenty strong for that purpose and you could even put some melamine on top for a nice finished look. I would put 2x4 vertically .. one at each corner and perhaps one at the middle of each side.

Since the AC needs access to cooling air, leave the vent side open. Then seal in the "out" side and direct the airflow up through the floor into the cavity. If there is an air return vent, direct air from the cavity back to that area of the AC.

I don't see why the footprint would be larger or smaller with the AC unit on top versus the bottom. My little Son of Ferm Chiller has a 3/4" ply base on wheels, and a 3/4 melamine floor and it'll hold 2 full carboys easily. Plus having the unit on top might make it a little top-heavy ... having the weight lower is better IMHO.

I'll have to go out a look at my little AC unit and see what I would do if I were making a ferm chamber out of it. One thing else you might consider ... if you open the unit up (al la Derrin) maybe you could isolate the cooling coils directly into the chamber itself ... then you could easily recirc cold air by adding a fan.

Dan

jward · Post by **jward** » Thu Nov 13, 2008 11:20 am

Adding the AC unit on a side just like if it were in a window would take up more floor space. Top and bottom designs would be the same. I agree a lower center of gravity is a definite plus. I'm figuring with a 24x45 base it should be fairly stable even with a top heavy (while empty) design. I was going to make a ramp so I could wheel my fermenter into the cold box. I also chose a 45" width over 48" because it will fit on the chrome shelving units I have which have wheels. Of course going mobile with the cold box means the fermenter will not roll inside.

If 3/4" plywood is good for the bottom then that may be a solution for the top too. I'll take a look as see what I have for scraps to test.

Don't you loose a good bit of floor space to holes in the bottom to move the air? My other cold box has bottom cooling. It's not a big deal. It has one hole for a muffin fan and a return slot in the back. It only holds one carboy or bucket and has lots of room for the holes. With the new cold box it could be a problem. The AC unit needs to move lots more air and fermenter wheels could be a problem.

When Derrin and I had the unit open it didn't look like one could do much better moving air then what's already there. The one fan motor spins the fan on both the condenser and evaporator sides of this AC unit.

I wonder at what point I should have purchased a refrigerator off of Craigslist?

dhempy · Post by **dhempy** » Thu Nov 13, 2008 12:11 pm

jward wrote:Adding the AC unit on a side just like if it were in a window would take up more floor space.

FWIW I'm not advocating a side mount ... more of a basement mount and then push air up. Just leave a side open so that the AC unit gets its required cooling.

On my Son of a Ferm Chiller I direct the air up a corner cut off at 45 degrees and then up the side to the top of the box. I would think you could make 2 corners this way. My return air is on the other side of the box on the floor. The cold air settles down across the carboys (and IMHO, makes it a bit more efficient). I use ice in the basement and recirc air over it. It is baffled so that the air must follow a path over the ice.

jward wrote:I wonder at what point I should have purchased a refrigerator off of Craigslist?

When you lose your tinkering spirit!

Dan

maltbarley · Post by **maltbarley** » Thu Nov 13, 2008 3:41 pm

jward wrote:I wonder at what point I should have purchased a refrigerator off of Craigslist?

I love to tinker when I have the time, but once you look at the costs of foam sheets, plywood, hardware and misc., buying a used fridge makes tons of sense.

backyard brewer · Post by **backyard brewer** » Thu Nov 13, 2008 6:06 pm

The time to get a fridge is if this box is going to be small. If you're building a 18cuft fridge then, buy the fridge. But if you're building 40-50 cuft of storage, make it!

jward · Post by **jward** » Sun Nov 30, 2008 8:54 pm

The 120V AC is wired up. I re-used the AC pigtail so it has a GFCI. I tested the circuit but the GFCI in the garage outlet tripped first. I added 2 switches. One to turn off the AC and one to control an interior fan. I still have connect the thermostat 24V wires and run the temp probe.

I have not decided what to do for the door. Any ideas? On the small cold box I used a PVC pipe and bungy cords. That sort of taco'ed the door but not so that it lost seal. I was leaning toward a pin based hinge but have not manged to find one.