– 13 –
OPERATION
GENERAL
All units are equipped with intermittent pilot ignition
systems. This system is 100% pilot burner shut off. See
Figure 11 for burner/gas controls. The pilot is lit and
extinguished during every cycle of operation. There is
no burning standing pilot.
On natural gas units, the ignitor will continue to spark
and pilot gas will continue to flow until the pilot flame is
proven.
LP (propane) gas units are equipped with 100%
lockout. The lockout function shuts off the main and
pilot gas valves if the pilot gas fails to ignite within 30
seconds.In order to initiate a reignition trial, the power
supply must be interrupted for 30 seconds.
A
O
F
F
8A
AA
O
N
8B
A
6
A
AAAAAA
AAAAAA
AAAAAA
AAAAAA
SPARK
1
M
V
2
MV/PV
3
4
GND
(BURNER)
P
V
5
6
7
8
9
24V
(GND
)
24V
TH-W
(OPT.)
Honeywell
WARNING
S8600M
CONTINUOUS RE-TRY
100% SHUTOFF IP
90 SEC. TRIAL FOR IGNITION
AA
9
AA
AA
1
3
5
4
BURNER DRAWER COMMON PARTS:
1.
MAIN BURNERS
2.
BURNER MANIFOLD
3.
AIR SHUTTERS
4.
BURNER SPRINGS
5.
MAIN BURNER ORIFICE
6.
TRANSFORMER
7.
PILOT TUBING
CONTROLS:
8A.
MAIN GAS VALVE (HONEYWELL)
8B.
MAIN GAS VALVE (WHITE RODGERS)
9.
HONEYWELL IGNITOR
10.
HONEYWELL PILOT BURNER
Figure 11 - Burner Components — Intermittent Pilot Ignition (Natural or Power Vented Duct Furnaces)
NOTICE: Check gas supply pressure (see chart 4).
Gas valves are suitable to a maximum pressure of
0.5 psi (14 inches water column). If the main gas
supply pressure for natural gas is greater than 14
inches WC (3.5 kPa), a stepdown pressure regulator
must be installed ahead of the gas valve. For LP
(propane) gas, the gas pressure supplied should not
exceed 14 inches WC (3.5 kPa).
The controls are located inside the compartment on the
access side of the unit. The input for single-stage firing is
based on full fire. On two-stage fire, the unit will fire 40%
of full fire on the first stage and full fire on the second
stage. When hydraulic modulating is used, the unit will
first fire at 40% of full fire and modulate up to full fire.
When electronic modulating is used, the unit will first fire
at 100% of full fire and modulate down to 40% of full fire.
C
10
7
