Calculating how much freon a system needs

[BronYrAur]

What is the proper way to calculate how much freon a refrigeration system needs? I am bidding on a system with medium and low temp racks in a mech room, with condensers on the roof, and evaporators throughout the building. How do I determine the amount of refrigerant that will be required? It's R-404a if that's important.

 

[AbbyNormal]

good question, I can only guess, coils are half liquid/half vapour, liquid line is so long, suction line is so long, you must know your temperature/pressures etc. Be all vapour in the compressors,make a receiver allowance. Maybe some one can confirm if that would put you in the ballpark,



Take the "V" out of HVAC and you are left with a HAC(k) job.

 

[chilled]

I'll guess about 1200lbs with no further information.