13 – operation – Sterling RT User Manual
Page 13
– 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 spark and pilot gas
will continue to fl ow until the pilot fl ame 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 a minimum of 5 minutes
to allow dispertion of unburned gas.
O
F
F
8A
O
N
8B
6
SPA
RK
1
M
V
2
MV/PV
3
4
GN
D
(BU
RNER)
P
V
5
6
7
8
9
24V
(GND
)
2
4V
TH-W
(OPT.
)
Honeywell
WARNIN
G
S8600M
CON
TINUOUS RE-TRY
100% SH
UTOFF IP
90 SEC. TRIAL
FOR IGN
ITION
9
1
3
5
4
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 fi ring is
based on full fi re. On two-stage fi re, the unit will fi re 50%
of full fi re on the fi rst stage and full fi re on the second
stage. When electronic modulating is used, the unit will
fi rst fi re at 100% of full fi re and modulate down to 40% of
full fi re.
C
10
7
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. PILOT
BURNER