duct size calculator, known as ductulator, depends on factors like the size of the space you're heating or cooling, air flow velocity, friction loss, and available static pressure of HVAC system.
To calculate CFM for each room, you must first perform HVAC load calculation for the whole house and for each room, using Manual J method. .
Use the ServiceTitan HVAC Load Calculator to figure the exact amount of BTUs each room requires for sufficient heating and cooling, and the capacity required for the entire house or building..
As example, say Room A needs 2,000 BTUs of heat gain based on HVAC room-by-room load calculations, and the home overall needs 24,000 BTUs, 000 BTUs ÷ 12,000 BTUs = 2 tons ✕ 400 CFM ton = 800 CFM.
Refer to CFM chart in HVAC manufacturer's specs to determine the external static pressure of the blower for that specific HVAC model.
As rule of thumb, the majority of systems have default friction rate of.05 wc, calculate it using ductulator chart, HVAC duct sizing software, or figure the friction rate yourself to get accurate measurement. .
The total length equals the length from the farthest supply outlet, through the equipment, and to the farthest return outlet — plus the equivalent lengths of all turns and fittings.
Instead of trying to calculate all of those individual instances of pressure loss, HVAC professionals measure the length of straight duct run that would create the same pressure drop.
To configure TEL, add up the effective lengths of all fittings in the most restrictive run and add that number to the length of the straight sections between the return supply in that run.
In ServiceTitan Ductulator, select the type and shape of duct you plan to use to get the correct corresponding measurements in the duct size chart..
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