Home-made fridge

[ChrisKlinger]

I'm setting up a coffee shop, and built an insulated corner into my bar, which I intend to use to display cold desserts. I scavenged a mini-fridge for everything but the evaporator, and tucked the compressor and condensor under the unit.

I'm using an evaporator from an old window-shaker, with a cap tube ( I forgot the length; if needed, I'll measure again).

I placed a muffin fan near the evap, routed to draw air through the evap.

Coldest temp I'm able to achieve is about 12C in the box. I've removed/compressed most of the fins on the evaporator to keep ice from blocking the unit, but if I run the fan, no dice, no ice, and 12C min. No fan, the evap ices, but i don't get the cold down from the evap to the rest of the box (evap is mounted to the ceiling of the unit).

I have some experience working on AC (as a helper when I was about 20, that being only a _few_ decades ago , but cold systems are completely new to me. What kind of low side pressure should I be looking for (R12)? Is my fan maybe too strong? Box not well enough insulated? Too large? (Maybe 20% more cubic space than the fridge the components came from).

Also, if I run a condensate drain to a pan, and place my (steel) condenser coil partially submerged, would I rust out in no time? increase eficiency? Be wasting my time?

Attached is a pic of the bar; the fridge is the part with the window (and a piece of wood holding up the condensate catch tray).

Any and all pointers appreciated.

[CCLPaul]

I think you are lucky to get 12, without a doubt the compressor will not match the evaporator and will last a very short while, you will need an engineer to do the design for you

[phil68]

Hi Chris, airconditioners are only designed to have the evaporator temp. at just above 0 deg. C, what you want is an evaporator temp. a good 10 or 15 degs. below what you are trying to achieve, in this case if you're after a temp. of 2 deg. C you need about -10 to -15 at the evaporator. You'd be much better off getting the condensing unit & evap. from an old display case that's intended to do the job.

[ChrisKlinger]

I'd love to be eble to find a freezer or display-case evap, but I've searched every repair shop, and nothing. New is out of my budget (my budget currently being zero).

I've gone over budget, way past my december opening goal, and my loans are eating me alive (best rate I could get was 3.5% _per month_! Remember, I'm in the third-world here, and a pretty backwards end of it at that.

If the best i can get is 10C, well, I'll have to live with it, at least for a while. However, the biggest difference I can see between the evap in my commecial fridge (which I bought used for R$300, or about US$130) is that the fins are thicker, and spaced much wider apart. That unit has a fan blowing across the evaporator like a hurricane (It's a Coke fridge with a glass door). Incidentally, the condenser on that unit is nothing more than about 20 feet of copper tubing, wound back and forth, with a fan to cool it; not particularly efficient, I imagine.

As far as low-side pressure, should I aim for 10-15PSI, and tear out excess fins on the evaporator, so that i don't immediately create an impenetrable block of ice? Should I reduce the speed of the fan, or does that have nothing to do with it.

Really appreciate the tips; the "hire an engineer" suggestions are about as helpful as a pocket knife in a gunfight.

[thebigcheese]

to be totaly honest u shudnt even be usin r 12! never mind miss matching condenser and evaporater

[Peter_1]

In Btrasil? Come on..

[Yuri B.]

I scavenged a mini-fridge for everything but the evaporator, and tucked the compressor and condensor under the unit.

I'm using an evaporator from an old window-shaker, with a cap tube

Hello.
Have I get it right - you have taken the evap from a window AC and placed it into the fridge - instead of the latter's original one?
Is the condenser "tucked under the unit" is able now to reject heat properly? If not you will not be achieving any cool on the evap.

[Brian_UK]

^^ Yuri, please check the dates.

OP was from three years ago and we haven't heard from him after his third post.

[Gary]

Oops... lol