What HP unit do I need?

[refermadness]

Hi everyone I am new to this board. I am a building engineer. I recently started a new job. The building I am in has 21 walk ins of all sizes and tempratures. HVAC is my strong point, but I have not done refrigeration in along time. Found this site and thought you guys would be a good reference place for me as I am the one respobsible for all our walk ins. What I have is a walk in freezer that went down last week. The box is 18 and 1/2 feet long by 11 feet wide. Currently there is a 2HP unit on this box that is about 18 years old with R-12. I have found many notes on this walk in and they have all said that the unit is undersized which I agree with. Can anyone tell me what size unit condenser and evaporator they think would work best for the application? They want to maintain temps around -15 degrees. Is there a reference or a rule of thumb out there for size of box and desired temp? Also which of the new refrigerants is best for a freezer? Thanks everyone sorry so long winded I am sure with a little help from you I will get back in the swing of things.

[wambat]

I believe for that size walk-in at - 15*F you need an approxamately 15,000 BTU condensing unit. Go to this page: I like the DJAL-026Z condensing unit, you may also have to change out the evaporator for a better match.
http://www.copeland-corp.com/cp_rf/i...2004CC-114.pdf