Filter
Top Products
167
JOHNSON CONTROLS
FORM 100.50-NOM6 (1207)
8
Supply Air Temperature Cooling Alarm (38)
The Unit Controller compares the supply air temperature
to the “SUPPLY AIR TEMP ALARM FOR COOLING”
and initiates the alarm based on the following criteria:
• All the stages of cooling have been on for 10 or
more minutes.
• The supply air temperature is 20 or more degrees
above the “SUPPLY AIR TEMP ALARM FOR
COOLING” set point for 10 minutes.
• The outdoor air is not 20.0° F or more warmer
then the “SUPPLY AIR TEMP ALARM FOR
COOLING” set point.
• The outdoor air damper is not open more then
20%.
Supply Air Temperature Heating Alarm (39)
The Unit Controller compares the supply air temperature
to the “SUPPLY AIR TEMP ALARM FOR HEATING”
and initiates the alarm based on the following criteria:
• All the stages of heating have been on for 10 or
more minutes.
• The supply air temperature is 20 or more degrees
below the “SUPPLY AIR TEMP ALARM FOR
HEATING” set point for 10 minutes.
• The outdoor air is not 20.0° F or more cooler
then the “SUPPLY AIR TEMP ALARM FOR
HEATING” set point.
• The outdoor air damper is not open more then
20%.
Economizer Minimum Position Alarm (40)
Prior to declaring this fault the Unit Controller checks the
outside air temperature and the economizer position. If
the outside air temperature is more then 20.0° F warmer
then the set point and the economizer is open more then
20%, the Unit Controller will close the economizer for
10 minutes and then check the supply air temperature.
If the SAT falls below the set point, the control will
declare an economizer minimum position alarm. The
Unit Controller will keep the economizer closed until
the end of the cooling cycle. It will then return the
economizer damper to its minimum position.
Space Temperature Trending Alarm (41)
This alarm will be generated based on the following
criteria:
• The “SPACE TEMP TRENDING ALARM TEMP”
and the “SPACE TEMPERATURE ALARM
TIME” must be set.
• The unit has been in a given mode of operation
for 10 minutes.
• The temperature is below or above the space
temperature set point and the trend continues to
be away from the space temperature set point and
the “SPACE TEMP TRENDING ALARM TIME”
has expired.
Duct Static Low Pressure Alarm (42)
This alarm is initiated on a VAV unit if after 35 seconds
of supply fan operation the duct static pressure is not
equal to or greater then 0.05” WC. When the alarm
becomes active the unit stops all operation and locks out.
This can be the result of a faulty Duct Static Pressure
Transducer or in the transition from an unoccupied to
occupied mode if the VAV boxes are wide open.
To check the operation of the duct static transducer
measure the VDC input between terminal DP+ wire
337 at the P21 connector and terminal DP- wire 338
at the P21 connector. Compare the voltage verses
the duct pressure the control indicates to Table 8-2 in
this section of the manual. Also verify that 24 VAC is
present between terminals “COM” and “EXC” at the
duct static transducer.
Hot Water Coil Freeze Alarm (43)
The alarm indicates the hydronic freeze stat switch has
opened. The 24 VAC source originates at the terminal
FSP, wire 389. The input to the control originates at
terminal FSI, wire 388.