Overrides: Water Valve, Flow, Fan - Trane Tracer VV550 Installation, Operation And Maintenance Manual

Sequence of Operations

Overrides: Water Valve, Flow, Fan

These three overrides have the same priority in the control sequences:
Water Valve Override
When the controller responds by driving the outputs within five seconds of receiving the
communicated valve override network variable. The actuators are driven as quickly as
possible to the correct position.
Water valve override has many enumerations. See the LonMark
Controller (SCC) functional profile for a complete list of all the water valve override
enumerations.
enumerations are treated as not valid.
Table 22.Water valve override controller operation
Communicated valve override
0 = Off, normal, or not valid
4 = Open, fully open all valves
5 = Close, fully close all valves
Other enumeration
There is no impact on the air valve or fan operation during water valve override.
Receiving the communicated valve override OFF request releases the water valves back
to the controller for normal operation. The controller automatically exits the water valve
override mode, changes the communicated valve override to OFF, and reverts back to
normal operation, if the configured manual override time (default = 600 minutes, [10
hours]) elapses since the last valid receipt of a communicated valve override.
Flow Override
The controller responds by driving the outputs within 5 seconds of receiving the
communicated flow override network variable. The actuators are driven as quickly as
possible to the correct position. The local zone sensor module flow overrides (single star
and double star) have priority over the communicated flow override.
The airflow override network variable (communicated flow override) has many
enumerations. See the LonMark
complete list of all the airflow override enumerations.
airflow override requests. Other enumerations are treated as not valid.
Table 23.Airflow override controller operation
Communicated flow override
0 = Off
Normal or not valid
3 = Flow percent
32
Table 22 shows the three supported water valve override requests. Other
Local
reheat
Normal
Open
Closed
Normal
®
Local or Air valve
remote
reheat
Normal Normal
Normal Control airflow to the requested percentage of
the configured maximum airflow
Air valve
Normal
Normal
Normal
Normal
Space Comfort Controller functional profile for a
Table 23
®
Space Comfort
Fan
Normal
Normal
Normal
Normal
shows the supported
Fan
Normal
Normal
CNT-SVX17G-EN