Electric Heat Operation - Trane Tracer AH540 Setup And Operation

Chapter 4 Sequence of operation
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The controller logic commands the exhaust fan to be energized/de-ener-
gized based on the target position of the economizing damper. Because of
device stroke time, the state of the exhaust fan may change before the
economizing damper reaches its target position.
If the exhaust fan start setpoint is set at or lower than the outdoor air
damper minimum position, the exhaust fan will be On continuously when
the outdoor air damper is at minimum position.
If the exhaust fan start setpoint is set higher than the outdoor air damper
minimum position (minimum ventilation) the exhaust fan will be Off dur-
ing periods of minimum ventilation. During economizer cooling operation
the exhaust fan start setpoint can be selected to compensate for the
increased outdoor ventilation.
The exhaust fan status binary input is present to detect operation of a
belt-driven exhaust fan. An Exhaust Fan Air Flow diagnostic is detected
when the control starts the exhaust fan and the exhaust fan status binary
input does not indicate operation after two minutes. This is an exhaust
fan latching diagnostic and discontinues exhaust operation until the diag-
nostic is reset. All other control functions continue to operate normally.

Electric heat operation

This sequence applies to both space temperature control and discharge
air temperature control, with differences as noted.
The Tracer AH540/541 supports two methods of controlling staged elec-
tric heat:
Staged electric heat using binary outputs.
•
Staged electric heat using a sequencer
•
For details, see "Staged electric heat" on page 61.
Electric heat operation can produce high discharge air temperatures if
the unit air flow rate is low or the entering air temperature is high. The
controller provides an electric heat discharge high limit control in addi-
tion to functional and safety limits of the product. In draw-through unit
configurations in which the electric heat source is positioned before the
supply fan in the air stream, the discharge air temperature is limited to
115°F (default). Blow-through electric heat unit configurations allow a
discharge-air-control high limit of 135°F (see Table 44 on page 79).
The Tracer AH540/541 controller supports only unit configurations with
one source of heating capacity, with the exception of a two-pipe
changeover unit with electric heat, if the controller is configured for space
temperature control (see "Two-pipe changeover" on page 53). When
hydronic-heating capacity is available, electric heat operation is disabled.
If hydronic-heating capacity is not available, electric heat is enabled.
Electric heat is normally disabled during:
Hydronic heating (two-pipe changeover unit)
•
Building automation system mechanical heating lockout is active
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CNT-SVX05B-EN