Specifications magic-pak: hw/hwc, Refer to figure 2-5 – Armstrong World Industries HWC PREMIER 183 User Manual
Page 38
SPECIFICATIONS
Magic-Pak: HW/HWC
2-28
SRM-HW/HWC 2/99
Detailed Sequence - HWC122, 182, 242, 302
(w/Fenwal 05-29 Ignition Control)
Refer to Figure 2-5
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.
L-1
on the
contactor
3.
L-1
on the
blower control board
4.
Terminal on the
transformer
marked
208V
or
240V
(whichever is being used)
Second black wire
1.
Supplies power to the
induced draft blower
2.
L-2
on the
contactor
3.
Common terminal on the
transformer
4.
T-2
on the
contactor
5.
Red wire on the
R
terminal of the
compressor
6.
Red wire to the common terminals on the
capaci-
tors
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 marked
24VAC
on the
ignition control
3.
Terminal R on the
blower control board
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 con-
trol board
. After 60 seconds, the heat speed relay
on the
blower control board
closes. This sends
line voltage from the terminal marked
HEAT
to the
circulating air blower
, starting the 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
W
terminal de-energizes, causing the blower
relay to open approximately 90 seconds later. This
interrupts the line voltage to the
circulating air
blower
and 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 i
gnition 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.
8.
When the call for heat is satisfied, the circuit be-
tween
R
and
W
is interrupted, de-energizing
W
.