Operating instructions

COMBUSTION
AIR
A93056
Fig. 42--Concentric Vent and Combustion-Air Roof
Termination (Dimension "A" is Touching or
2-in. Maximum Separation)
COMBUSTION AIR
J
COMBUSTION
AIR
A96129
Fig. 44_Raised Sidewall Termination When Wall
Penetration is 12 in. or Less Above Snow or Grade
(Dimension "A" is Touching or 2-in. Maximum
Separation)
VENT
A93057
Fig. 43--Concentric Vent and Combustion-Air Side
Termination (Dimension "A" is Touching or
2-in. Maximum Separation)
a. Inducer Prepurge Period- As the inducer motor IDM
comes up to speed, the pressure switch contacts PRS close
to begin a 15-second prepurge period.
b. Igniter Warm-[ p- At the end of the prepurge period, the
Hot-Surface igniter HSI is energized Ibr a 17-second
igniter warm-up period.
c. Trial-for-Ignition Sequence- When the igniter warm-up
period is completed the main gas valve relay contacts
GVR-1 and -2 close to energize the gas valve GV, the gas
valve opens, and 24 vac power is supplied for a field-
installed hmnidifier at the HUM terminal. The gas valve
GV permits gas flow to the burners where it is ignited by
the Hot Surihce Igniter HSI. After 5 seconds, the igniter
HSI is de-energized and a 2-second Flame-Proving period
begins.
d. Flame-Proving- When the buruer flame is proved at the
flame-proving sensor electrode FSE, the furuace control
CPU begins the blower-ON delay period and continues to
hold the gas valve GV open. If the buruer flame is not
proved within two seconds, the control CPU will close the
gas valve GV, and the control CPU will repeat the ignition
sequence for up to three more Trials-For-Ignition before
_t _'_ .... " COMBUSTION AIR
COMBUSTION AIR
34
A96130
Fig. 45--Sidewall Termination of More than 12 in.
(Dimension "A" is Touching or 2-in. Maximum
Separation)
going to Ignition-Lockout. Lockout will be reset auto-
matically after three hours, or by momentarily interrupting
115 vac power to the furuace, or by interrupting 24 vac
power at SEC1 or SEC2 to the furnace control CPU (not at
W, G, R, etc.).
If flame is proved when flame should not be present, the
furuace control CPU will lock out of Gas-Heating mode
and operate the inducer motor IDM until flame is no longer
proved.
Blower-On Delay- If the buruer flame is proven, the
blower motor is energized on HEAT speed 66 seconds (040
through 120 sizes) or 45 seconds (140 size) after the gas
valve GV is energized.
Simultaneously, the electronic air cleaner tenninal EAC-1
is energized and remains energized as long as the blower
motor BLWM is energized.
Blower-Off Delay- When the thennostat is satisfied, the
R-to-W circuit is opened, de-energizing the gas valve GV,
stopping gas flow to the burners, and de-energizing the