I think there is some power in considering the 'step-up' rounding calculation. Let's say your load calc ends up being 26000 BTUhr with manual J. Normally you'd put in a 30000 BTUhr unit. I'd play with the numbers to see what that 2.5 ton unit does in the space specced for 26000 BTUhr. ..basically, determine the temperature spread in reverse. Often it can cover the difference. Of course this depends on the climate.
It's a little different for me. Minnesota is a place where the lakes and prevailing moisture convection brings our dew point is sky high from June through August and we have muggy wet summers where a properly sized AC is critical. I'd rather have a few days where the hottest point indoors gets a little bit uncomfortable versus a bunch of low/partial load days where I feel like I'm swimming in humidity inside. I imagine Texas doesn't have as much moisture in the air and this is less of a factor. My house was stepped up to 2 tons and I'd rather have a 1.5 ton compressor for better moisture control. Heat isn't nearly as much of a big deal when the moisture is in control. Moisture doesn't feel comfortable.
|