HydroTherm VGAB Series Installation, Operation And Maintenance Manual page 14

OPERATING SEQUENCE FOR STEAM BOILERS
EQUIPPED WITH STANDING PILOT, VENT
DAMPER, HI-LIMIT & 67 LWCO
i, MOTOR DRIVES VENT DAMPER TO CLOSED POSITION AND
REMAINS CLOSED DURING STANDBY,
8, STANDING PILOT REMAINS LIT,
3, SENSING CIRCUIT IS CONTINUOUSLY MONITORED,
4, THERMOSTAT (OR OPERATING CONTROL) CALLS FOR HEAT,
5, DAMPER BLADE OPENS,
6, DAMPER END SWITCH CLOSES (PROVING VENT DAMPER
OPEN)
7, MAIN VALVE IS ENERGIZED
8, UNIT OPERATES UNTIL THERMOSTAT (OR OPERATING
CONTROL) IS SATISFIED,
9, SYSTEM RETURNS TO STANDBY WITH DAMPER CLOSED,
FIELD WIRING
FACTORY WIRING --
PRESSURE 67
CDN-I-RDI_ LWCO TFE]RHJ]S T A T
OR OPERATING
VHT
I
BLK
DAMPER
lY:III
_-TA4L _
BLK
_/HT
LD
L__p
(
I
I
I
L
SWITCH
GAS
VALVE
LI5/B4V
TRANSF, LI
IF ANY OF ]]dE ORIGINAL _fIRE AS SUPPLIED WITH THE APPLIANCE
MUST BE RL-Pt_ACED, IT MUST BE RDPLACED WITH TYPE M_37 (I05°C)
WIRE OR ITS EQUIVALENT.
LI L2
{-_ l15V AC
LL.L.UJJJJU
i15/24V
PFY'F_
PRESSURE SPILL T'STAT DR
'_PF__ TH _TQR
ROLLOUT
SWITCH GAS VALVE
SPILL AND RDLL[IUT SWIECHES USE]] WlHEN
INPUT IS LESS THAN 300,000 BTUH
42-5736 REV,2
OPERATING SEQUENCE FOR SREAM BOILERS
EQUIPPED WITH STANDING PILOT, VENT DAMPER
HI-LIMIT & CG-400 SERIES LWCO
1. MOTOR DRIVES VENT DAMPER TO CLOSED POSITION AND
REMAINS CLOSED DURING STANDBY.
2. STANDING PILOT REMAINS LIT.
3. SENSING CIRCUIT IS CONTINUOUSLY MONITORED.
4. THERMOSTAT (OR OPERATING CONTROL) CALLS FOR HEAT.
5. DAMPER BLADE OPENS.
6. DAMPER END SWITCH CLOSES (PROVING DAMPER OPEN).
7. MAIN VALVE IS ENERGIZED.
8. UNIT OPERATES UNTIL THERMOSTAT (OR OPERATING
CONTROL) IS SATISFIED.
9. SYSTEM RETURNS TO STANDBY WITH DAMPER CLOSED.
FIELD WIRING
FACTORY WIRINGLOWcuToFFWA.ER PRESSURE ? THERMOSTATcoNTRoLOR OPER.
(N) (H) (B) BUR CONTROL
[....... NER rh,
/I' f_ ? o T SPILL
_T_ ,
/ _ I / SWITCH / I _ 11Y/24V
( I ! I I ) _ " RLU_ I / TRANSF.
/I __
, .TTI
BLK GASVALVE
IF ANY OF TH EORIGINAL WIRE AS SUPPLIED WITH THE BOILER
MUST BE REPLACE[), USE A SIMILAR WIRE OF 10B_ C RATING.
H
115VAC
LiiJ,_,LLZ.L_
115V/24V
LWCO
(H) (B)
SPILL SWITCH PRESSURE
CONTROL
T'STAT OR
OPER. CNTRL
fVENT
t J--J RO&O H GAS VALW:
NATURAL GAS 3 THRU 7 SECTION.
[P GAS 3 THRU 9 SECTION.
SPILL & ROLLOUT SWITCHES ON 3 THRU 6 SECTION ONLY.
N
.-j
60392 REV2
FIGURE 2.15: WIRING DIAGRAM & OPERATION
SEQUENCE FOR BOILERS EQUIPPED WITH
STANDING PILOT, VENT DAMPER & MCDONNELL-
MILLER WATER CUT-OFF (EXCEPT FOR VGA-350 &
VGA-400 N.G.)
FIGURE 2.16: WIRING DIAGRAM & OPERATION
SEQUENCE FOR BOILERS EQUIPPED WITH
STANDING PILOT, VENT DAMPER & CG-400 SERIES
LWCO (EXCEPT FOR VGA-350 & VGA-400 N.G.)
14