Transcript Plenum Run
copyright Mestek, Inc. 2006 What’s High Velocity Air Conditioning? High Velocity Systems • • • • A central, split system… • not a window shaker, or a minisplit Unique air handler and duct system Uses aspiration and blending not air change Roughly half the CFM of conventional systems • 5 ton unit is 1150 CFM • Average 250 CFM/Ton What is Small Duct High Velocity Air Conditioning? • SDHV indicates a blower & indoor coil combination that: • • Is designed for, and produces, at least 1.2 inches of external static pressure when operated at the certified air volume rate of 220-350 CFM per rated ton of cooling; and….. when applied in the field, uses high velocity room outlets generally greater than 1000 fpm which have less than 6.0 square inches of free area. -- ARI/DOE definition Conventional AC • Diffusion and throw. • Air change. • Duct placement works for heating OR cooling, NOT BOTH. Hi-Velocity Aspiration • Less air volume • Greater ∆T & ∆P • Circulates room air • Condenses more water vapor Central Return • • • Air mixing vs. Air change Less return air volume Cooling by temperature, not volume Sensible vs Latent • • • “Dry Bulb” Measured with thermometer Windows, insulation, solar gain • • • • “Wet Bulb” Measurement with Sling Psychrometer People, cooking, etc. Important to comfort •Infiltration Sensible/Latent Comfort • • • • • • Temperature and evaporation Cold and clammy Hot and dry High efficiency conventional - thin coil Spacepak - 6 row thick coil Psychrometric chart graphically explains Psychrometric Chart More Psychrometrics 11 SEER Minimum • • D.O.E. has raised the the minimum efficiency for Spacepak from 10 to 11 Space Pak currently has more mix & match combinations that meet or exceed 11 SEER requirement than any other high velocity manufacturer