copyright Mestek, Inc. 2006

What’s High VelocityWhat’s High Velocity

Air Conditioning?Air Conditioning?

High Velocity SystemsHigh Velocity Systems• A central, split system… •not a window shaker, or a mini-

split• 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 What is Small Duct High Velocity Air Conditioning?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

• Diffusion and throw.

• Air change.

• Duct placement works for heating OR cooling, NOT BOTH.

Conventional ACConventional AC

• Less air volume

• Greater ∆T & ∆P

• Circulates room air

• Condenses more water vapor

Hi-Velocity AspirationHi-Velocity Aspiration

Central ReturnCentral Return

• Air mixing vs. Air change

• Less return air volume

• Cooling by temperature,

not volume

Sensible vs LatentSensible 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 ComfortSensible/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

PsychrometricPsychrometricChartChart

MorePsychrometrics

11 SEER Minimum11 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