also keep in kind that when autosizing the result is generally that the
system autosizes based on the sum of all coil loads without accounting
for diversity, resulting in what would be an oversized system from a
design perspective. depending on your equipment curves this can result
in low part load efficiency which will affect your results, sometimes in
a significant manner. One way to check is to look at your equipment
operation and see the PLR ranges it is operating in as well as comparing
equipment capacity to actual loop loads. After a prelim run you can then
hard size the primary equipment to a reasonable value based on the
actual loop loads if you don't have equipment selected at your point in
the design process.

Peter