19
To remove manometer from gas valve:
1. Remove manometer hose from outlet pressure boss.
2. Turn outlet pressure tap screw in to seal pressure port
(clockwise, 7 in-lb. minimum).
3. Turn on electrical power and gas supply to the
system.
4. Turn on system power and energize valve.
5. Using a leak detection solution or soap suds, check
for leaks at pressure boss screw. Bubbles forming
indicate a leak. SHUT OFF GAS AND FIX ALL LEAKS
IMMEDIATELY.
CAUTION
t
o
PREvEnt
UnRElIablE
oPERatIon
oR
EqUIPMEnt
daMaGE
,
tHE
GaS
ManIfold
PRESSURE
MUSt
bE
aS
SPEcIfIEd
on
tHE
UnIt
RatInG
PlatE
. o
nly
MInoR
adjUStMEntS
SHoUld
bE
MadE
by
adjUStInG
tHE
GaS
valvE
PRESSURE
REGUlatoR
.
6. Relight all other appliances turned off in step 1 of gas
input check. Be sure all pilot burners are operating.
M
aIn
b
URnER
f
laME
c
HEck
Flames should be stable, soft and blue (dust may cause
orange tips but they must not be yellow) and extending
directly outward from the burner without curling, floating or
lifting off.
no
x
S
cREEn
c
HEck
Verify that the alignment of the NOx screens is at 6
o’ clock. In jurisdictions that do not require low NOx
emissions, NOx screens may be removed.
t
EMPERatURE
R
ISE
c
HEck
Check the temperature rise through the unit by placing
thermometers in supply and return air registers as close
to the unit as possible. Thermometers must not be able to
sample temperature directly from the unit heat exchangers,
or false readings could be obtained.
1. All registers must be open; all duct dampers must be
in their final (fully or partially open) position and the
unit operated for 15 minutes before taking readings
2. The temperature rise must be within the range
specified on the rating plate.
notE: a
IR
tEMPERatURE
RISE
IS
tHE
tEMPERatURE
dIffEREncE
bEtWEEn
SUPPly
and
REtURn
aIR
.
With a properly designed system, the proper amount of
temperature rise will normally be obtained when the unit
is operated at rated input with the recommended blower
speed.
If the correct amount of temperature rise is not obtained, it
may be necessary to change the blower speed. A higher
blower speed will lower the temperature rise. A slower
blower speed will increase the temperature rise.
notE: b
loWER
SPEEd
MUSt
bE
SEt
to
GIvE
tHE
coRREct
aIR
tEMPERatURE
RISE
tHRoUGH
tHE
UnIt
aS
MaRkEd
on
tHE
RatInG
PlatE
.
NORMAL SEQUENCE OF OPERATION
H
EatInG
This unit has one (RS) Manual Reset Limit Control Switch.
Check the limit to make sure it has not tripped. The limit
may arrive at the job site tripped as a result of shipping
shock.
If the venter motor comes on, but the unit does not attempt
ignition, check if the ALS (Auxiliary High Limit Control
Switch) requires resetting.
1. With electricity and gas turned on, the system switch
in the “HEAT” or “AUTO” position and the fan switch
in the “AUTO” position, the thermostat will close the
circuit between unit terminals R and W (R-W) when
the temperature falls below the thermostat setting.
2. D1 on IIC energizes venter motor contactor.
3. Venter motor contactor energizes the venter motor.
4. Operation of the venter motor closes the pressure
switch PS located in the burner compartment.
Unless excessive temperatures or shipping shock
have opened high limit control ALS, power is fed to
the integrated ignition control, which then initiates a
15-second pre-purge time delay. During this period,
the venter fan will clear the combustion chamber of
any residual gas.
5. After the pre-purge period, the ignition control
energizes the Wl-C gas valve and simultaneously
initiates a “three (3)-try” spark ignition sequence.
6. When the burners are ignited, a minimum one (1)
micro-amp DC current will flow through the flame
between the sensor electrode and the grounded
burner.
7.
When the controller proves that the flame has been
established, it will keep the gas valve energized and
discontinue the ignition spark.
8. If the control is unable to ignite the burners after its
initial attempt, it will initiate another purge and spark
sequence. A third purge and spark sequence will
be initiated if the second attempt is unsuccessful.
If the third attempt is unsuccessful, the controller
will close the gas valve and lock itself out. It may be
reset by momentarily interrupting power. This may be
accomplished by briefly lowering the room thermostat
set-point below room temperature, or by shutting off
the main power to the unit.
