Making a cold box...need some thoughts

[prrriiide]

SWMBO has given me the green light to expand my brewing operation. My first project is to build a cold box in my garage that will allow me to do lagers and ales at the same time.

What I want to do:

I want to build a box 8' long X 4' high X 4' wide out of plywood, insulated with pink foam board. I will put an AC unit in one end of this box. Then I want to divide the box in half to make two 4 X 4 X 4 chambers. The dividing wall I want to make as two pieces of 1/4" plywood with opposing cut-outs. One piece of plywood will be movable so that I have a set of adjustable louvers. This is how I will control the temperature in the ale chamber. The lager chamber will have the AC unit blowing into it, and the louvers will allow the ale chamber to stay cool, but at a higher temp than the lager chamber. Each chamber will have its own insulated access door.

Any advanteges/disadvantages/ideas on this scheme?

 

[BargainFittings]

I can give some general advice. Insulate to 2" of foam. Seal all the edges with foil type tape. Check all closure points for air tight seals.

The center divider needs to be insulated also. Are you going to let the air flow in/out of the ale chamber and use restriction to moderate its temp?

I think a fan and flap type closure using a temperature controller would give you better control. A simple house type thermostat and a DC fan or two would work out for air movement.

Edit: insulate the bottom and cover it with some plywood for durability. Paint everything with a couple coats of durable paint.

 

[Bjornbrewer]

I think you have a pretty good handle on it. Here's a link to something similar someone did: https://www.homebrewtalk.com/f51/dual-zone-fermentation-chamber-166195/

I think instead of two large pieces of plywood as louvers, just build another insulated wall between the two sides and put in an adjustable heat register.

Also, are you going with top or front access? I'd suggest front so you wont have to lift carboys.

Are you going to have a way of heating this as well?

 

[prrriiide]

I think instead of two large pieces of plywood as louvers, just build another insulated wall between the two sides and put in an adjustable heat register.

I have thought about that. I haven't been able to mouse out how to adjust it externally, without opening the door, though. But I do like the simplicity of it. Perhaps an all-thread/nuts/washers rig and figure out a way to attach it to the register adjuster, then out through a small hole in the box?

Also, are you going with top or front access? I'd suggest front so you wont have to lift carboys.

Ya, front all the way. This baby is going to be 4' deep. I don't want to have to install an a-frame and come-along to get to my beer.

Are you going to have a way of heating this as well?

I hadn't really thought about heating it. This winter has been an anomaly here in Tennessee, it usually isn't as cold for as long as it was this year. Winters are usually pretty moderate. But if I need a heater, I have a space heater with an auto-thermostat on it. I can set it for 60° and pretty much forget it.

 

[Bjornbrewer]

I hadn't really thought about heating it. This winter has been an anomaly here in Tennessee, it usually isn't as cold for as long as it was this year. Winters are usually pretty moderate. But if I need a heater, I have a space heater with an auto-thermostat on it. I can set it for 60° and pretty much forget it.

if you use a dual stage temp controller, you could have that control the space heater and AC unit.