Specifications magic-pak: hw/hwc, Refer to figure 2-6 – Armstrong World Industries HWC PREMIER 183 User Manual
Page 44
SPECIFICATIONS
Magic-Pak: HW/HWC
2-34
SRM-HW/HWC 2/99
Detailed Sequence - HW
(w/Fenwal 05-29 Ignition Control)
Refer to Figure 2-6
POWER
Line Voltage
When the service disconnect switch is closed, power is
sent to the unit (unit in standby, no signal from the
thermostat
). Power (208 - 230 volts A/C) is supplied
to both black wires located in the junction block on top
of the unit.
Line voltage will be present at the following locations:
First black wire
1.
L-1
on the
ignition module
2.
Terminal on the
transformer
marked
208V
or
240V
(whichever is being used)
3.
Circulating air blower capacitor
terminal
Second black wire
1.
Supplies power to the
induced draft blower
2.
Common terminal on the
transformer
3.
Terminal
L-1
on the
blower control board
Low Voltage (24 VAC)
With the unit at rest (no call from the
thermostat
), 24
volts A/C will be found at these points:
1.
Red wire exiting the top of the unit
2.
Terminal
R
on the
blower control board
3.
Terminal
NO
on the
limit switch
4.
Terminal on the
transformer
marked
24V
CALL FOR HEAT
Line Voltage
The
thermostat
closes the circuit between
R
and
W
.
The following is the sequence of operation for the line
voltage side of the unit:
1.
Terminal
TS
(24-volt) energizes on the
ignition
control
, causing a relay in the
ignition control
to
close. This sends line voltage to the terminal
marked
IND
, causing the
induced draft blower
to
start.
2.
When
W
is energized, a 24-volt signal is also sent
to the
W
terminal on the
blower control board
.
The 24-volt signal starts the timer on the
blower
control board
. After 60 seconds, the relay on the
blower control board
closes. This sends line
voltage from the terminal marked
L-1
to the terminal
marked
H
on the
blower control board
, starting
the
circulating air blower
. The
induced draft
blower
and the
circulating air blower
continue to
operate until the heat call is satisfied, interrupting
the circuit between
R
and
W
. The
ignition control
de-energizes the
induced draft blower
relay,
interrupting L-1 power to the
induced draft blower
.
The
induced draft blower
stops several seconds
later. The
W
terminal on the
blower control board
de-energizes, starting a 90-second blower “off”
delay. This interrupts the line voltage to the
circu-
lating air blower
and after 90 seconds, the blower
shuts down.
Low Voltage
1.
A call for heat closes the circuit in the
thermostat
between
R
and
W
, sending a 24-volt signal to the
white wire on the unit.
2.
The white wire goes to the
C
terminal on the
limit
switch
,
ignition control
terminal
TS
and terminal
W
on the
blower control board
.
3.
When
W
energizes, the timer starts a countdown to
circulating air blower
“on”. The blower starts in
approximately 60 seconds.
4.
The 24-volt signal sent to the
TS
terminal closes a
relay in the
ignition control
. This starts the
induced draft blower
by energizing terminal
IND
on the
ignition control
.
5.
As the
induced draft blower
comes up to speed
and creates enough negative pressure, the
pres-
sure switch
closes. The 24-volt signal is sent from
the
pressure switch
to one side of the Normally
Closed
manual reset rollout switch
. If the
rollout switch
is closed, the 24-volt signal is
passed through the switch to the
P.SW
terminal on
the
ignition control
. This initiates a 30-second
pre-purge period.
6.
After the 30-second pre-purge period, a trial for
ignition starts by energizing the
spark
terminal and
the
V1
terminal simultaneously. The 24-volt signal
from
V1
energizes the
gas valve
solenoid, causing
it to open. These actions cause the burners to light.
7.
After the burners are lit, a flame sense is picked up
by the
flame sense rod
located at the opposite
end of the burner rack from the
spark electrodes
.
The flame sense signal is sent to the
S1
terminal of
the
ignition control
. The unit continues to operate
as long as
W
is energized.