AC Sizing Differences

[SLOBuds]

I'm getting vastly different results when trying to calculate BTU requirements for a single-room mini-split AC.

The AHM calculator is coming up with numbers around 15-16k. The This Old House calculator is coming up with approx 9600. Both of these calculators seem to be cloned across the internet. Example, Consumer Union uses the same calculator as AHM.

What worries me is that I am reminded everywhere that too big is bad, and too small is bad.

Should I not worry and go with bigger, or split between the 2, or go with smaller, or ???

Thanks,

 

[Willl]

'Manual J' is the best way to figure tonnage size.
Do a google search on 'manual J' and read up about it.

Here's a sample program.

HVAC Software, HVAC-Calc for Heat Loss, Heat Load Calculations

 

[shaley]

You will probably be OK with a 1 Ton unit. Even if a mini split (ductless) is over sized it does not suffer as bad from the "low dehumidification" like a central unit does as the fan runs continuously on the ductless. Also, most units I have seen have a dehumidify mode whereby the fan speed is reduced during cooling so it will pull extra water out of the air.