Hello,
We would like to change the size of condenser of the existing installation. Which factors should we take into account?
Also what are the EN 12900 and ARI rating conditions?
Your question is equal to asking: "My company wants to buy a new truck. What size truck should I tell them to buy, and what Rules should the company that builds the truck follow to be safe for the next 60 years?"
You have not told us: Size, rating, pressure, cooling fluid, service, temperature, environment (air temperature,water temperature maximum/minimum, water flow rate), environmental restrictions, country, applicable Code, industry, reason why the current condenser is "wrong sized". You have not told us costs of power, service duration and seasonal changes of the load, of the cooling water OR cooling air - or whatever the cooling fluid could be!), operator quality and training, degree of automation, reason for the service (critical, important, side-stream production, convenience), cost of fuel, cost of whatever gas (probably steam) that you are condensing ....
/sarcasm. Yes, I am not a mind reader. 8<)
Yes, I am trying to educate the original writer about what (at a minimum) is needed to ask a simple six word question to a problem that cannot be answered with a textbook, a career, and an entire industry.