I've been asked to design the refrigeration system for a walk in meat cooler at a customer's house. He's a farmer/hunter and wants to store his meat in it.

The guy is set in his demands, so a couple things MUST be done his way:

He's had 2 railroad containers buried behind his garage and has a hole cut between the two of them. The walls and roof are being insulated with 6" foam, the floor is wooden. He's set on using an insulated exterior door for the entrance. None of this is my idea, so I know it's not the correct way to do this.

Anyway, each "room" is 6'9"x7'6"x18'7" (originally 8'x8'x20'). There is a 30" passage between the 2 boxes about 30" from the wall.

I'm suggesting he go with 2 evaporators separated with solenoids and a single condensing unit outside. We'll need about 20' of piping for each line, suction and liquid.

Where can I find the information, charts or program to determine what size equipment I need for this job? I've repaired plenty of these things but never designed one, so this is my "big break" into the process.

Thanks for you help.