How do you choose the condensor size

[tuccillo]

Quick question to the pros. If you need 48K BTUs based on a load calculation ( say at 95F outside/75F inside ) design point, do you put in a 4 ton condensor or a 5 ton condensor? My point is a 4 ton condensor probably doesnt produce 4 tons at those design temperatures, it may very well be 3.5 tons. In other words, "4 tons" may be a marketing number ( or does does produce 4 tons but not at 95/75 design temperatures). Do you guys look at the actual capacity at your design temps when choosing equipment or just go with the "marketing" number?

[docholiday]

The spec sheets or product data sheets give you tha actual capacities at ARI conditions. Generally that is pretty close to design. Dont assume 4 tons is 48,000. And more importantly make sure your unit matches the sensible and latnet load of the house, not nessesarily the total load.

[tuccillo]

Originally posted by docholiday
The spec sheets or product data sheets give you tha actual capacities at ARI conditions. Generally that is pretty close to design. Dont assume 4 tons is 48,000. And more importantly make sure your unit matches the sensible and latnet load of the house, not nessesarily the total load.

Hi Doc, yes, that is my point - a "4 ton unit" is probably not 4 tons at 95/57 temps. In that case, you would more likely put in a "5 ton unit" since it is closer to 48K BTUs while not being less than 48K BTUs ?

[beenthere]

As doc said you need to check the product spec sheets.

By changing which indoor coil is matched to the outdoor, you can get more or less btu's.

Some coils are high sensible, others are higher latent.

Manual S will help with deciding what size and what match up to use.

[dash]

Load is 48,000 at 95 outdoor,75 indoor.


ARI is at 80°F indoors.To convert to 75°F,835 sensible btus ,times 5° difference,time 1.6,equals a deduct of 6,680 btus,gonna need 5 tons.

The deduct is per 1000 cfms ,so 1600/1000= the 1.6

Some mfrs sheets have "other" indoor specs,but 80° is the most common.