HydroTherm VGAB Series Installation, Operation And Maintenance Manual page 13

OPERATING SEQUENCE
STEAM BOILERS EOUIPPED WITH VENT
DAMPER FLOAT TYPE LWCO AND IID
MOTOR DRIVES VENT DAMPER TO CLOSED POSITION AND
REMAINS CLOSED DURING STANDBY.
SENSING CIRCUIT IS CONTINUOUSLY MONITORED,
THERMOSTAT (OR OPERATING CONTROL) CALLS FOR HEAT.
DAMPER BLADE OPENS .
DAMPER END SWITCH CLOSES (PROVING DAMPER OPEN),
IF NO FAILURE EXISTS, THE PILOT VALVE AND IGNITER
ARE ENERGIZED.
PILOT IS IGNITED AND SENSOR SENSES FLAME.
MAIN VALVE IS ENERGIZED AND IGNITER BE-ENERGIZED.
UNIT OPERATES UNTIL THERMOSTAT (OR OPERATING
CONTROL) IS SATISFIED,
SYSTEM RETURNS TO STANDBY WITH DAMPER CLOSED.
THERHO STA T/_-"_ FIELD WIRING
OR OPE_ t )
CONTROL F FACTORY WIRING-
I
SPILL __J I PRESSURE
SWITCH w _ CONTROL
51 k_.' _ _ ROLL[2]-I /TRANSF.
"_2--- ! S_TCH #
M-M _:67 12h _ i BLK 0--_ _1--- -
LOW WATER b-V 60HZ
CUTOFF
II GAS VALVE _ $8600
I --
(TIE) MV/PV _ I BP_N I o [ MV/PV
II
tl _ -l-e t PV
° ,IYz ,,
('_'?_"- I I_ [24(u-q_)
_P_
il3ol II _ _ !..Lj2'_v
_'--/--1 4L_ U PLUE ...._ IGNITER[-] ,__J_ ^_ _
IF ANY OF THE ORIGINAL WIRE AS SUPPLIED WITH THE BOILER
MUST BE REPLACED, USE A SI2LIqLAR WIRE OF 105 ° C RATING,
H
F=u
115 V
AC
t NNIENU.U
l15V/24V
RDLLObT
SWITCH MANUAL RESET .....
SPILL
SWITCH
T'bTAJ
UK
i - -- PRESSURE [:]PER CNTRL I
CONTROL
t
N
I
F GAS VALVE
5
CI-H) MV Bid< m
(TR) MV/PV
CIq-I-TR) PV _
' _E--
IG-N_ T'ER [_
SENSOR
SPILL AND
RE]I_LI]IJT SW-[TCHES USED WHEN
INI=LFf
IS LESS
THAN
300,000
BTUH
3"8600
-e MV
-_ [ MV/PV
G-ND
-6 I 24(EN]])
24V
_ SPAPJ<
42-5702
REV, 4
OPERATING SEQUENCE
STEAM BOILERS EQUIPPED WITH VENT DAMPER,
CG-400 SERIES LWCO AND liD
1. MOTOR DRIVES VENT DAMPER TO CLOSED POSITION AND
REMAINS CLOSED DURING STANDBY.
2. SENSING CIRCUIT IS CONTINUOUSLY MONITORED.
3. THERMOSTAT (OR OPERATING CONTROL) CALLS FOR HEAT.
4. DAMPER BLADE OPENS.
5. DAMPER END SWITCH CLOSES (PROVING DAMPER OPEN).
6. IF NO FAILURE EXISTS, THE PILOT VALVE AND IGNITER
ARE ENERGIZED.
7. PILOT IS IGNITED AND SENSOR SENSES FLAME.
B. MAIN VALVE IS ENERGIZED AND IGNITER DE=ENERGIZED.
9. UNIT OPERATES UNTIL THERMOSTAT (OR OPERATING
CONTROL) IS SATISFIED.
10. SYSTEM RETURNS TO STANDBY WITH DAMPER CLOSED.
FIELD WIRING
FAC]ORYWIRING 9 THERMOSTAToR OPER. LOW WATER CONTROL
CUTOFF PRESSURE
(N) (H)21 P1 (B) o BURp2 A NER SPILLILONTRO[ EL _
ow /-- RANS L
II Iv [ r' q--
/
IT
/
WHT
I L,,SVGOHZ
I / / BLK _" --
(TH) MV BLK MV
VENT RED 24(GND)
DAMPER _ I
24V
Z
IF ANY OF THE ORIGINAL WIRE AS SUPPLIED WII'H THE BOILER
MUST BE REPLACED, USE A SIMILAR WIRE OF 105_ C RATING.
H N
7"- ,,SVAC
115V/24V
Fi"CCf]
LWCO
]
Ir'F2
=T °
(H) (B)
SPILL SWITCH
SPILL AND ROL LOUT SWITCHES
ON 3 THRU 6 SECTION ONLY
P_L:EoSNSU#E L O]ii _ _i_!NIIll L
I
GAS VALVE
[ T
58600
(TH) MV MV
(TR) MWPV _ o MV/PV
PV
(TH TR) PV GND
24(GND)
24V
IGNITER
SENSOR SPARK
60393 REV,2
FIGURE 2.13: WIRING DIAGRAM & OPERATION
SEQUENCE FOR BOILERS EQUIPPED WITH
INTERMITTENT PILOT, VENT DAMPER &
MCDONNELL-MILLER WATER CUT-OFF
FIGURE 2.14: WIRING DIAGRAM & OPERATION
SEQUENCE FOR BOILERS EQUIPPED WITH
INTERMITTENT PILOT, VENT DAMPER &
CG-400 SERIES LWCO
13