Trane IntelliPak 2 Series, Инструкция по установке, эксплуатации и обслуживанию

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102 RT-SVX24Q-EN
continue to operate as long as a heating demand exists
and the system switch is “On”.
Once the heating demand has been satisfied, the
combustion blower and the Honeywell ignition control
board is de-energized.
N No otte e:: The above sequence is the same for Propane.
The orifices are smaller and the manifolds are
adjusted to different values
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When a heating requirement exists, the Rooftop
Module (RTM) starts the supply fan and sends a
request for heat to the Heat Module. The Heat Module
closes contacts and starts the combustion blower
motor through the combustion blower relay. The
supply airflow switch and the combustion air switch
closes. Power is applied through the high limit cutout
to the Honeywell ignition control board. The ignition
control board begins the pre-purge timing cycle with
the damper in the light off position and the low fire
start interlock is closed.
At the end of the pre-purge cycle, the ignition
transformer and the pilot solenoid valve are energized.
This starts a 10-second trial for pilot ignition. When the
pilot flame is established and sensed by the flame
sensing rod, the stage 1 of the main gas valve will
begin. The gas butterfly control valve is in the low fire
setting by the linkage arm connection between the
combustion air actuator and the butterfly valve. The
system will operate in the low heat mode until there is
an additional call for heat established by closing the
contacts on the Heat Module.
If the flame rod does not detect a pilot flame within the
10 second trial for ignition period, the ignition control
board will lockout. The combustion blower motor will
continue to operate as long as a heating demand exists
and the system switch is “On”. Once locked out on
flame failure, the IC board will not reactivate the
ignition/combustion control circuit until it is reset
manually. To do this, press the reset button on the
front of the IC board case. A set of relay contacts is
available for external use for heat fail (Information
Only). Once the heating demand has been satisfied, the
combustion blower and the Honeywell ignition control
board is de-energized.
Modulating Gas Sequence of Operation
The control system for the rooftop units is wired to
ensure that the heating and cooling do not occur
simultaneously. Refer to the modulating heat wiring
diagram that shipped with the unit while reviewing the
following sequence of operation. As you review the
sequence of operation, keep the following in mind:
• The furnace will not light unless the manual gas
valves are open and the control circuit switch is
closed.
• The control systems are wired to ensure that
heating and cooling cannot occur simultaneously.
• The unit supply fans must run continuously so
airflow switch will stay closed.
• Modulating Gas heat is available during both
occupied and unoccupied operation.
When there is a call for heat, the heat module energizes
the combustion blower, which causes the combustion
airflow switch to close. The ignition control board will
energize providing that the indoor air flow switch, high
limit, and low and high pressure gas switches are
closed. The ignition control board then causes the
combustion air actuator to drive the inlet air damper to
the fully open position for a 30 second pre-purge. The
pre-purge time does not begin until the purge interlock
switches are made.
After the pre-purge, the combustion air actuator drives
the inlet air damper and the gas butterfly control valve
to a nearly closed position for light off. When the Low
fire interlock switch is closed the ignition transformer is
energized, the igniter begins to spark and the pilot
valve opens. This begins a 10-second trial for ignition
period during which the flame rod must detect the
flame. If does not detect a flame at the end of the
period, it will shut down and lock out the ignition/
combustion circuit.
Once the pilot flame has been established, the heat
module will open the main gas valve and auxiliary gas
valve. After the main flame is established, the pilot
valve closes. The ignition sequence is completed and
the heat module will drive the combustion air actuator
to a firing rate based on a 2-10 VDC signal. The gas
butterfly control valve will respond through the
connecting linkage. The heater will continue to run
until the call for heat is removed or a limit opens.
Following the completion of the call for heat, there is a
15-second post-purge.
Flame Failure
In the event that the Ignition Control (IC) board loses
the “proof-of-flame” input signal during furnace
operation, it will lock out and must be manually reset
(Combustion blower motor continues to run as long as
a heating requirement exists and control circuit switch
is ON.)
Once locked out on flame failure, the IC board will not
reactivate the ignition/combustion control circuit until it
is reset manually. To do this, press the reset button on
the front of the (IC) board case.
A set of relay contacts is available for external use for
heat fail (Information Only).
N No otte e:: The modulating gas heaters are factory adjusted
for safe operation and to reach the nameplate
rated firing MBH for most areas of the country.
The proper air/gas ratio must be reached by the
service tech during start-up.
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