I am half way through building one of these.
It was pretty much the first thing I embarked on when I decided I wanted to start brewing beer back in March. But as winter was approaching, I built the structure, then fited it with a fan heater running through a thermostat. Obviously It's almost time to switch over to refridgeration.
The room measures roughly 2m x 2m x 2m. I built the frame out of 70x35mm pine, braced on the four walls with that steel angle they use on houses. I insulated the floor by cutting pieces of 75mm polystyrene to fit in between the studs and nogans, then screwed 19mm yellow tounge flooring to both sides on it. For the walls and the roof I screwed 100mm polystyrene, and filled the gaps with space-invaders - This is a standard contruction technique for houses, then the outside gets rendered, which I plan to do to mine, it will look great (my brother is a renderer, so I got all this stuff cheap, and good advice). The door is a piece of 75mm cool-rom panel, this is 75mmpolystyrene with colorbond (about 2 or 3mm thick) on each side. I dug out the poly on one side of the door panel, and screwed in a piece of hard wood so I could mount hinges on it. Then I used a fridge seal to seal it up. The fridge seal sits on a few pieces on colorbond, that I installed specifically around the door so it could seal.
The whole things sits on castors, so I can roll it around the garage and move it if need be. The only major problem, is that I stuffed up the calcualtions of height, so to get it out my garage door, I will have to take the castors off, un-hook the garage door and drag it out.
I have calulated, that with a temperature difference of 20 C between inside and out, I should be losing about 300W, so I dont need a very powerful cooling unit to run it, a fridge motor would probably be fine. Even ona 40 C day, maintainig 4 C inside, I need less than 600 W of cooling capacity which isnt much.
As for the refridgeration part, Ive thought long and hard over winter about what I would do about it. You cant just use a regualr split system, as the temp control is in the wrong range. I got a quote on one that could control the correct temp range, and it was $4000 (as opposed to the same thing designed to control temps 18-30C, is about $300-400 from ebay or bunnings).
What I was going to do, was get small chest freezer, cut the lid off, or even maybe cut the whole thing in half. And install the part with the refridgeration motor into the room, by cutting a hole the right size in the polystyrene, sliding it through the hole and sealing it up. I have such a freezer at home, and it has a vent for cooling the heat sink on the back, so if I installed it with that vent pointing out the side of the room, then sealed it up, and run it off a thermostat...I should be sweet.
But, afer seeing Jamils unit, I never thought of that type of wall unit. The main problem with most air-con systems is they have some type of temperature set-point with a minimum of 18 C. They also are often inverter type syetms, that I dont think will handle being turned on and off frequently (I could be wrong about this, can any one confirm/deny?) Those old wall mount types are usually just on-off units, so they would be perfect to run of a thermostat. I think I am off to ebay to see if I can find a suitable one!!
If you want pics, let me know, I could probably post them tomorrow.
Edit: Incidently, I have a friend who is a refridgeration mechanic, he too told me that my freezer cutting idea will not last more than a week. He also pointed out, that due to condensation, my frame is likely to rot unless it is varnished or something.
