Gas Heat - Trane IntelliPak with Symbio 800 Installation, Operation And Maintenance Manual

Sequence of Operation
Table 35. Multi zone-VAV unit – Supply fan operation
Staged Gas
Occupied Heat Full
Maximum Heat Full
Morning Warm Up Full
Daytime Warm Up Full
Unoccupied Heat Full
Occupied Cool Supply NA – not allowed
Air Tempering
Single Zone-VAV units have limited supply fan speed
modulation in Occupied Heat modes of operation when
modulating gas heat or modulating electric heat are
configured; otherwise, the supply fan operates at full
capacity in all other heat operating mode
All heat types, when the control terminates heating
capacity or exists a heating mode; a 5-minute post heat
timer is enforced. This keeps supply fan On to remove heat
from the unit before transitioning to a cooling mode or
cycling the supply fan off.

Gas Heat

There are three types of gas heat available: Staged gas,
Modulating gas and Ultra Modulating gas. Each type of gas
heat is composed of one or two manifolds, each manifold
can have one or more burners. As demand for heat
increases, incremental stages of heat are added. All
burners on a manifold ignite in sequential order starting
with manifold A. When manifold A has staged up to full
capacity, staging starts on manifold B (when equipped). As
the demand for heat decreases, the highest burner on the
highest manifold will turn off first. The Off and Running
status of each manifold and burner are provided on the
user interface.
When the gas heat is in Warmup or Running state, the
Symbio 800 controller will report the status as Running.
Burners will not turn on if the heater minimum off timer is
active, the heater inter-stage timer (3-minutes) is active, or
modulating heater is not at maximum rate. Burners will not
turn off if the heater is in process of starting, heater is
undergoing a retry or modulating heat is not at a minimum
rate.
Modulating and Ultra Modulating gas heat types modulate
the first burner on manifold A. The minimum and maximum
modulation rates are defined by each stage of heating. The
modulating stage controls to maximum modulation rate
before another burner stage is added. Likewise, the
modulating burner must reach minimum rate before a stage
is subtracted.
Staged Gas Heat Sequence
Call for heat initiated
1. A call for heat is initiated by the digital Modbus signal.
84
Modulating Gas Staged Electric Heat
Modulate Full
Full Full
Full Full
Full Full
Full Full
Modulate NA
2. Draft Inducer is energized, an air pressure switch
3. At end of pre-purge period, Spark and Gas Valve are
4. Burners ignite.
5. Flame detected by flame sensor and control operates
6. Unit continues in operation until the call for heat
7. The Gas valves are de-energized and unit enters its
If ignition is not achieved within the trial period, the gas
valve is shut off; the inducer continues to run for a 30
second post-purge period. Additional ignition trials follow
the specified sequence. If 3 attempts for ignition have
occurred without flame detection, the control will lock out.
The control board will reset after one hour. Control lockout
can be cleared by cycling the power off for a minimum of 5
seconds.
If flame is lost once it has been established, the control will
shut off the gas supply within 2.0 seconds and enter the
post-purge period. Control will allow a predetermined
number of flame losses before lockout.
If flame sensor indicates presence of flame during purge
period when no flame should be present, the inducer will
remain energized but the gas valve will remain off until the
cause of the "false flame" is removed.
If the air pressure switch is closed when the inducer is de-
energized, or does not close after the inducer is energized,
the control will wait a predetermined time for the air switch
to correct itself, if not then lock out. Control will go into
lockout with all outputs off.
Modulating Gas Heat Sequence
Call for Heat Initiated
1. A call for heat is initiated by the digital Modbus signal.
2. The gas heat control board will then go through a
Modulating Electric
Heat
Modulate
Full
Full
Full
Full
Modulate
closes initiating pre-purge for 30 seconds.
energized for an ignition trial period for 4 seconds.
in steady state heating condition.
terminates.
post-purge for 30 seconds.
system check to ensure that the high temperature limit
and rollout switches are closed, the air pressure switch
is open, and the modulating valve is positioned
correctly.
External Heat
Modulate
Full
Modulate
Modulate
Modulate
NA
RT-SVX063G-EN