Bard W24G2DA, Руководство по установке

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Manual 2100-592C
Page
39 of 69
31. SEQUENCE OF OPERATION –
HEATING
On a call for heat from the thermostat, the induced
draft blower is energized. Once sufficient draft is
established, the pressure switch contacts close and
the ignition system is energized. The direct spark
ignitor will be energized allowing gas to flow. At the
same time the main valve is energized, a 30-second
blower delay timer is activated.
After this delay, the heating speed blower relay
energizes. The blower will begin operating and
remain in operation until the set delay time after the
call for heat has been satisfied. (See Tables 10-15
for selectable blower off time delays.) This timing
sequence guarantees blower on, blower off operation.
This unit is equipped with a flame rollout switch
which is wired in series with the control circuit. This
is a manual reset switch and is used for the purpose
of preventing possible fire hazard in the event of a
system malfunction. If this switch has opened the
control circuit, there could be a possible system
malfunction. Some of the conditions that might cause
a rollout to occur are blockage or sooting of primary
heat exchanger, overfiring of furnace due to improper
main burner orifices or incorrect manifold pressure,
insufficient combustion air or installation deficiencies
with respect to return air duct design or sizing.
Once the problem has been resolved, reset the switch
by pressing down on the reset button on top of the
switch. See Figure 17 for additional information.
32. SEQUENCE OF OPERATION –
COOLING
On a call for cooling from the room thermostat, the
high speed blower relay will be energized as well as
the compressor contactor. Following termination of the
cooling cycle, the blower motor will continue to run for
one minute.
See Figure 17 for additional information.
The unit may be equipped with a low ambient control
for lower outdoor temperature operation in the cooling
mode. If equipped with this optional control the
condenser fan will not operate immediately upon
compressor start up, and will cycle on and off until the
condensing pressure remains above 280 PSIG.
DEHUMIDIFICATION – Dehumidification is controlled
through a humidistat and is independent of the
thermostat. On a call for dehumidification mode of
operation, the compressor, blower and three way valve
of the unit are energized through circuit R-3 to provide
dehumidification. Dehumidification will continue until
the humidistat is satisfied.
If there is a cooling call issued through circuit R-Y, it
will cancel dehumidification sequence (de-energize the
reheat valve) until the cooling call is satisfied. If the
dehumidification call is still present when cooling call
is satisfied, the compressor will continue to operate
and the reheat valve is reenergized.
Any time there is a call for heating mode of operation
through circuit R-W1, the dehumidification mode will
cancel and the system will return to heating operation.
Dehumidification is delayed 45-60 seconds on start up
after any heating cycle is complete.
Any time the indoor coil temperature falls below 32°,
the compressor will be de-energized until the coil
temperature rises above 57°.
(Refer to Section 34 for dehumidification relay logic
board.)