But I'm not sure if they have a 1 ton condensing unit
I'm not sure what evap that is but
Originally Posted by KB Cool
I'm guessing 300 on model is around 3000 btu
But I'm not sure
Maybe he can google it.
Maybe he's okay? But, it just won't pull down?
Originally Posted by shaka
I have tried to google it. Found nothing so far.
I installed it because he said here put this in. He and I both know I don't know refrigeration.
He built the box and I ran the wire, installed the condenser, evap, piping, etc....
I got it up and running but it wont get down to 40* where he wants it.
I guess you can say its more of an experiment for me. I can say it works. So I did my job. LOL
Well, i'm sure the guy can make the box smaller!! Maybe change it into a 4x4!!!
Originally Posted by gravity
The system matches up OK, however it simply doesn't have enough capacity to do the job.
The Bohn C-30 evaporator is rated at 3000 Btuh at a 10ºF TD, where the TD is the box temperature minus the evaporator temperature. A 10ºF TD is a good number to use for a general purpose walk-in, so for a 40ºF box you would select a condensing unit which has a capacity of approximately 3000 Btuh at a 30ºF evaporator temperature.
The Tecumseh AEA4440, which is a 1/3 HP unit, has a capacity of 3020 Btuh at 30ºF evap, so it is a good match for the C-30 evaporator.
The expansion valve should be selected to the actual system capacity in tons and not the nominal horsepower. For 3020 Btu, that would be 3020/12000 or about 1/4 ton, so a nominal 1/4 ton TXV should work.
As for the box load, there are some good calculator available or you could use a quick-select chart. Here's a screenshot of Heatcraft's quick selection guide for a 35ºF walk-in, which will give you an idea of what this box really needs.
As you can see, an 8 x 8 cooler should have a system with at least 7000 Btuh capacity for general duty. That would bump you up to a 3/4 HP unit and matching evaporator.
From the numbers posted, I can see you were measuring superheat at the compressor. For a refrigeration system you should always first set your superheat when the box is near design temp at the outlet of the evaporator close to the TXV bulb location where 6-8ºF SH is good, but no more than 10ºF. Then check it at the compressor where it should be no less than 20ºF.
Subcooling isn't of much use with a system that has a receiver because adding or removing refrigerant doesn't affect SC significantly, it just changes the level in the receiver.
my 8x8 w/i has a 12k window shaker that I made some mods to the stat and added a evap air defrost. Works well, pull down is within an hour after start up.
Unless you are going to run this box all the time I do not think you have the pull down your buddy will be looking for, then add a hot deer or 2 and a couple guys working makes it worse.
I gave up the refrigeration world a long time ago, just speaking of my own personal box.
Originally Posted by icemeister
Your my hero
sweet...thanks for the info