Hi-Velocity Duct rules of thumb
- 8” duct required for 1.5- 3 ton systems
- 10” duct required for 3.5 & five ton systems
- 14” insulated return duct for 1.5-3 ton systems, 16” for 3.5 ton, 4 ton & 5 ton systems
- Minimum eight 2” outlets per ton Minimum four “super duct” outlets per ton
- Minimum 10’ length on a run (even if you have to coil up the run)
- Systems operate at 250 CFM per ton, 30 CFM per 2” outlet, 60 CFM per super duct outlet
- Outlet packages come in 10’ = 100% Air Flow and 15’ = 90% Air Flow
- (Adding a 5Ft splice or 20’ = 80% Air Flow)
- (Adding a 10Ft Splice or 25’= 65% Air Flow)
- HEZ blower unit can be ordered as 230 or 115 volt units
- Chilled Water Coil Delta T = 8 to 10 DegF@ 44 EWT & 2.5 GPM per Ton
- Delta T Air side 15-20 Deg F, Delta T across coil for better humidity removal should be 29 DegF Must have a minimum of 18” of strait duct directly off the unit prior to elbow or tee.
- Use branch take-offs rather than bull head tees.
- Bullhead tees must have maximum 60/40 balance.
- Branch take-offs allow for up to 70/30.
CFM per outlet= FPM x .022 for 2” FPM x .042 for HE
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