Setting The External Pressure - Johnson Controls (H,Y,C)IDM012B21S Installation And Maintenance Manual

● If a lower sound level is required, install field-supplied silencer.
● The facility design should be "Unit External Static Pressure = Duct Pressure Loss + Suction /
Discharge Pressure Loss".
If duct pressure loss fall below the external static pressure, airspeed will increase and noise levels
along with it. Also, water may splash out from unit and the motor protection circuit activated.
Problems such as the inability to adjust airspeed can occur if the external unit static pressure fall
below the duct pressure loss. Adjust the airflow control damper or shift the static pressure control
switch to an equal level between the external static pressure and duct pressure loss. (refer to
"Setting the External Pressure" section for the details.)
● Basically, this unit is configured to install the ducts on the inlet side and the outlet side. Ask for
more information on using return ducts in the ceiling.
Silencer
Thermal
Insulation
Damper for Fine
Adjusting Air Volume
Air Outlet
5.6

Setting the External Pressure

Refer to Section 8.6 "External Static Pressure Setting".
14
Canvas Duct
Indoor
Unit
Service Access Panel
Horizontal
(17-11/16 inches x 17-11/16 inches)
Static Pressure
*: Before Shipment
Figure 5.7 Duct Connection Example
Canvas Duct Silencer
Air Inlet
(with Air Filter)
in.W.G. 0.14 - 0.20* - 0.32
(Pa) (35 - 50* - 80)
Damper for
Adjusting Air Volume
Outdoor Air
(with Air Filter)
An air filter which
can collect dust.
ERV
(Energy Recovery Ventilation)
P00792Q-rev.2