Two stage A/C has nothing to do with this.
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Most laundry driers and hot water tank's use indoor air for combustion as well as most all 80% furnaces take combustion air from the indoor area, but if you have too many appliances using internal combustion air then yes you will have to account for the lost indoor makeup air as this can lead to negitive pressure inside the home and really cause problems, but this is not anything that can not be easily overcome with the addition of a air intake into the basement to supply combustion air for all needed appliance's.