Duct Sizing

sdbrown1

hello,
I have a 2200 sq ft house. with 1st 2nd and 3rd floor.
what size duct should i use for each floor.

coolmen

first and formost you need to determine size equipment that will heat and cool your house. load calculation must be performed to decide size of furnace and a/c. hvac talk forum has the load calc that you can do this on your own. In the past in new jersey the company i worked for would calculate by rule of thumb. 2200 sq x8 x5 = 88,000 btu heat /2= 44,000 btu cooling (3 1/2 tons) beware things are differant in other parts of the country.(To big a system= mold,noise wasted energy. to small hot and cold= angry,sick
3.5 tons= 1400 CFM
being 3 floors.is it best to go with 2 systems.or multi zones.YES
or you will never get even temps.with out knowing the lay out of the house, sq ft of each floor furnace location,

eager2start

How is it that you can develop mold from having an oversized system?

coolmen

An over sized system will shut down to quickly or not run that long due to very cold air being place in the area,(feeling cold but clamy/damp.like a cool damp basement). A air conditioners job is to remove moisture from the area.A properly sized a/c will run long enough to remove the water that is in the air.

A good effianct a/c will run longer then a oversized one will. and still be very comfortable in the area. load calc is the only true way.

coolmen

MOLD needs moist air and a food source like sheetrock and or other household materials.