Hi all, first post.
No, I'm not going to ask you to size a system for me. I just have a general question about what I think might be a slightly "gray" area when it comes to sizing.
If you did a load calc and it was exactly midway between two sizes, would you go up, or down, and why?
If you went down, would the system then be unable to achieve the "design" indoor temperature on the hottest day(s) of the year? If it couldn't (and I don't see how it could), would this seem like a worthwhile compromise to you in order to maintain system efficiency for the majority of the cooling season?
If you went up, would you be sacrificing some energy efficiency and dehumidifying capacity (due to increased cycling) in order to achieve sufficient cooling on the hottest day(s) of the year?
It seems to me that the "perfect" size is achieved when the system can just exactly keep up with the load on the hottest day(s) of the year, or maybe just barely exceed cooling demand, with very little cycling.
It also seems to me that it's very difficult to hit this exact spot, especially if a properly-performed load calculation lands right between two sizes; say, you come up with 33,000 BTU's, right between 2.5 and 3 tons.
So, which way do you go - up, or down?
I'm thinking that down might be the way to go, and maybe just be slightly uncomfortable for a few days a year, while maximizing system efficiency for most of the cooling season.
Any thoughts you could share? Thanks in advance.