29
NOTE:
Both readings may be taken simultaneously and read di-
rectly on the manometer if so desired. If an air conditioner coil or
Electronic Air Cleaner is used in conjunction with the furnace, the
readings must also include theses components, as shown in the
following drawing.
4. Consult proper tables for the quantity of air.
If the total external static pressure exceeds the maximum listed on
the furnace rating plate, check for closed dampers, registers, un-
dersized and/or oversized poorly laid out duct work.
Checking Static Pressure
(80% Furnace Shown, 90% Similar)
B
URNER
F
LAME
The burner flames should be inspected with the burner compart-
ment door installed. Flames should be stable, quiet, soft, and blue
(dust may cause orange tips but they must not be yellow). Flames
should extend directly outward from the burners without curling,
floating, or lifting off. Flames must not impinge on the sides of the
heat exchanger firing tubes.
Burner Flame
T
O
AVOID
PERSONAL
INJURY
OR
DEATH
,
DO
NOT
REMOVE
ANY
INTERNAL
COMPARTMENT
COVERS
OR
ATTEMPT
ANY
ADJUSTMENT
.
E
LECTRICAL
COMPONENTS
ARE
CONTAINED
IN
BOTH
COMPARTMENTS
.
C
ONTACT
A
QUALIFIED
SERVICE
AGENT
AT
ONCE
IF
AN
ABNORMAL
FLAME
APPEARANCE
SHOULD
DEVELOP
.
WARNING
S
AFETY
C
IRCUIT
D
ESCRIPTION
G
ENERAL
A number of safety circuits are employed to ensure safe and proper
furnace operation. These circuits serve to control any potential
safety hazards and serve as inputs in the monitoring and diagno-
sis of abnormal function. These circuits are continuously moni-
tored during furnace operation by the integrated control module.
I
NTEGRATED
C
ONTROL
M
ODULE
The integrated control module is an electronic device which con-
trols all furnace operations. Responding to the thermostat, the
module initiates and controls normal furnace operation, and moni-
tors and addresses all safety circuits. If a potential safety con-
cern is detected, the module will take the necessary precautions
and provide diagnostic information through an LED.
P
RIMARY
L
IMIT
The primary limit control is located on the partition panel and
monitors heat exchanger compartment temperatures. It is an au-
tomatic reset, temperature sensor. The limit guards against the
overheating resulting from insufficient air passing over the heat
exchanger.
A
UXILIARY
L
IMIT
The auxiliary limit control is located either on or near the circula-
tor blower and monitors heat exchanger compartment tempera-
tures. The control is an automatic reset, temperature sensor. It
guards against overheating resulting from insufficient air pass-
ing over the heat exchanger. The auxiliary limit control is suitable
for both horizontal right and horizontal left installations. Regard-
less of airflow direction, it does not need to be relocated.
R
OLLOUT
L
IMITS
The rollout limit controls are mounted on the burner/manifold
assembly and monitor the burner flame. They are manual-reset,
temperature sensors. This limit guards against burner flames not
being properly drawn into the heat exchanger.
P
RESSURE
S
WITCHES
The pressure switches are normally-open, negative air pressure-
activated switches. They monitor the airflow (combustion air and
flue products) through the heat exchanger via pressure taps lo-
cated on the induced draft blower. These switches guard against
insufficient airflow (combustion air and flue products) through
the heat exchanger.
