Technical Guide

5126749-YTG-A-0715
Johnson Controls Unitary Products 23
UNIT TYPICAL ROOF CURB INSTALLATION
EXTERNAL STATIC PRESSURE SETUP
To measure external static pressure:
• Measure the supply air static pressure
• Record this positive number
• Measure the return air static pressure
• Record this negative number
• Treat the negative number as a positive and add the two numbers together
• This is total system static
SUPPLY
AIR DUCT
TO POWER SUPPLY
RETURN
AIR DUCT
FIELD-SUPPLIED
DISCONNECT
SWITCH
CONTROL WIRING TO
INDOOR THERMOSTAT
ROOF CURB
ROOF
CONDENSATE
DRAIN
A0389-001