Valve And Damper Selection - Honeywell AUTOMATIC CONTROL SI Edition Engineering Manual

VALVE AND DAMPER SELECTION

Pneumatic valve and damper actuators are shown in these
examples. If actuators are electric, certain ones need not be spring
return unless a specific reason exists. Table 1 outlines general
Actuator Application
Dampers
Outdoor air
Relief air (to outdoor)
Return air
VAV fan inlet vanes
VAV box
Multizone hot deck, cold areas
Multizone hot deck, hot areas
Valves
AHU chilled water
Terminal reheat
Preheat in OA below 1.5 C
Preheat in OA above 1.5 C
Other hot water
AHU steam heating
Steam humidifier
1
Return air dampers need no springs if the associated fan is delayed upon start-up to allow the RA damper to properly
position to assure that the fan does not start with both RA and OA dampers closed.
2
If a duct temperature sensor is located near a hot water or steam coil, leaving the coil under control (with a setpoint of
27 C to 38 C) during equipment shutdown can provide added freeze alarm protection. If variable flow hot water
pumping is provided and a duct low temperature control senses freezing conditions, hot water valves may be
positioned approximately 25% open if a temperature sensor is not available.
ENGINEERING MANUAL OF AUTOMATIC CONTROL
Table 1. Valve and Damper Actuator Selection Guide.
Pneumatic Actuators
System
Shutdown
Closes
Opens
Closes
Owner Preference
Opens
Closes
Closes
2
Opens
Closes
2
Closes
Closes
207
AIR HANDLING SYSTEM CONTROL APPLICATIONS
actuator selection. The table indicates actuator positioning desired
on system shutdown and loss of motive force.
System
Loss of Air Shutdown
Closes Closes
Opens Opens
Closes Closes
Opens Owner Preference Owner Preference
Opens
Closes Closes
Opens Closes
Opens
Closes
Closes
Closes
Closes
Electric Actuators
Loss of
Electricity
Closes
1
Opens
Closes
Opens
Closes
Stays same
2
Opens
2
Stays same
Closes