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CNT-SVX05A-EN
Sequence of operation
diagnostic and discontinues exhaust operation until the diagnostic is reset.
All other control functions continue to operate normally.
Electric heat operation
™
The Tracer
AH.540 controller does not support electric heat. Use of the
controller's heat output to control electric heat elements for heating purposes is
highly discouraged. Using the heat output to control electric heat could cause
dangerously high cabinet temperature conditions when the supply fan is off or
when low airflows exist.
Morning warm-up
The morning warm-up function initiates a special heating sequence to raise
space temperature to occupied conditions. This sequence is especially useful for
a building occupancy transition from unoccupied to occupied.
The Tracer AH.540 controller performs morning warm-up differently for
constant volume space temperature control than constant volume discharge air
control or variable air volume control.
Constant volume space temperature control
The controller keeps the outdoor air damper closed (when a mixing box is
present) anytime during a occupied, occupied bypass, or occupied standby
mode when the space temperature is 3ºF or more below the heating setpoint.
The damper remains closed indefinitely (no time limit) during morning warm-
up until the space temperature is within 2ºF of the effective heating setpoint.
The outdoor air damper normally is open to a minimum position during the
occupied mode when the controller turns on the supply fan. The damper
normally is closed during:
• warm-up/cooldown mode
• unoccupied mode
• certain diagnostic conditions
• low ambient damper lockout
• anytime the supply fan is off.
Morning warm-up can also be a communicated request from a Trane Tracer
™
Summit
building automation system. When the Tracer AH.540 controller
receives a communicated morning warm-up request, heating mode is enabled
and the outdoor air damper closes. The controller remains in morning warm-up
until a different request is communicated.
Constant volume discharge air control or variable air volume control
In these modes, the Tracer AH.540 controller requires a space temperature input
(hardwired or communicated) and setpoint input (hardwired, communicated,
or default value) to initiate the morning warm-up sequence of operation.
On a transition from unoccupied to occupied (occupied bypass or occupied
standby) the controller compares the space temperature to the heating
setpoint. If the space temperature is 1.5° F below the heating setpoint, morning
warm-up is initiated. The outdoor air damper closes (or remains closed) and the
controller's heat/cool mode is heating.
The morning warm-up control sequence has no time limit upon a transition
from unoccupied to occupied, when the controller is configured for constant
volume discharge air control or variable air volume control modes.
Morning warm-up can also be a communicated request from a Trane Tracer
™
Summit
building automation system. When the Tracer
receives a communicated morning warm-up request, heating mode is enabled
and the outdoor air damper closes. The controller remains in morning warm-up
until a different request is communicated.
™
AH.540 controller
51
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