Trane Tracer AH540 User Manual

Exhaust fan operation
CNT-SVX05B-EN 59
Low ambient damper lockout
The controller closes the outdoor air damper during any heating, cooling,
or economizer mode of operation or occupancy when extreme outdoor air
temperatures exist. This condition disables outdoor air damper ventila-
tion and economizing functions, but low ambient damper lockout does not
affect other unit operations.
The outdoor air temperature must rise 9°F (5°C) above the low ambient
damper lockout setpoint before economizing and ventilation become pos-
sible again.
Exhaust fan operation
This sequence applies to both space temperature control and discharge
air temperature control.
The exhaust fan/damper is coordinated with the unit supply fan and out-
door damper operation. The exhaust output is energized only when the
unit supply fan is operating and the outdoor damper position is greater
than or equal to the configurable exhaust fan start setpoint. The exhaust
fan output is disabled when the outdoor air damper position drops 10%
(configurable) below the exhaust fan start setpoint. If the enable point is
less than 10% (configurable), the unit turns On at the start setpoint and
Off at zero.
Table 23. Relationship between outdoor temperature sensors and damper position
Outdoor air damper
Outdoor air temperature
Occupied or
Occupied bypass
Occupied standby Unoccupied
No or invalid outdoor air
temperature
Open to occupied mini-
mum position
Open to occupied standby
minimum position
Closed
Failed outdoor air sensor Open to occupied mini-
mum position
Open to occupied standby
minimum position
Closed
Outdoor air temperature
less than the low ambient
damper lockout setpoint
1
Closed Closed Closed
Outdoor air temperature
present and economizing
feasible
Economizing, damper
controlled between occu-
pied minimum position
and 100%
Economizing, damper
controlled between occu-
pied standby minimum
position and 100%
Open and economizing
during unit operation, oth-
erwise closed
Outdoor air temperature
present and economizing
not feasible
2
Open to occupied mini-
mum position
Open to occupied standby
minimum position
Closed
1 The low ambient damper lockout setpoint is a configurable temperature setpoint used to close the outdoor air damper, regard-
less of occupancy, when extreme outdoor air temperatures are present.
2 The Tracer
AH540/541 controller disables economizing if the mixed-air temperature sensor is not present or is not valid.

Trane Tracer AH540 Specifications

General

Brand	Trane
Model	Tracer AH540
Category	Controller
Language	English