Weil-McLain FLAME GUARDIAN WMBC-1A Use and maintenance manual

Part Number 550-141-807/0298
LGB
Gas–fired boiler
Contents
Flame Guardian WMBC-1A
RM7895C Controller Electronic Pilot System
IRI
Control Supplement
I. Installation ..................... 2
II. Gas piping ...................... 5
III. Wiring ............................. 5
IV.Startup ......................... 10
V. Sequence of operation 11
VI.Parts list ....................... 12
Indicates presence of hazards that can cause severe personal injury,death or
substantial property damage.
Indicates special instructions on installation, operation or maintenance that
are important but not related to personal injury or property damage.
This Control Supplement must only be used by a qualified installer/service
technician. Read these instructions completely before beginning the
installation. Failure to follow these instructions can cause severe personal
injury, death or substantial property damage.

Part Number 550-141-807/02982
LGB (Series 2) — Control Supplement
IInstallation
1. For use with LGB-6 through 12 boilers.
2. LOCAL INSPECTOR MUST CERTIFY BOILER FOR IRI COMPLIANCE.
3. Assemble pilot burner and flame sensor to main burners with pilot brackets. See Figures 2
and 3. Install ground wiring as shown in Figures 2 and 3.
4. Reinstall burner assemblies. See Table 1 for pilot burner and flame sensor locations.
5. Assemble control panel to boiler. See Figure 1.
6. Install gas controls as shown in Figure 4, page 4.
7. IRI installations require manual reset controls. Weil-McLain recommends installing manual
controls in addition to standard as required by local inspector. Refer to the LGB Boiler
Manual,“Boiler Controls”section.
a. Steam boilers require a manual reset Low Water Cutoff and manual reset Pressure Limit
Control.
b. Water boilers require a manual reset Low Water Cutoff and manual reset Temperature
Limit Control.
Front of
Boiler
Panel
Drill (7) 1/8“
Holes In Jacket
to Mount
Bracket
Drill (7) 1/8“
Holes In Jacket
to Mount
Bracket
Drill (3) Holes in Front
Drill (4) Holes in SideDrill (4) Holes in Side
55BGL
Figure 1
Mount control panel to jacket
as shown
Table 1
Pilot burner and flame sensor
locations
Boiler Model Flame Sensor * Pilot Burner *
LGB-6 29
LGB-7 211
LGB-8 213
LGB-9 215
LGB-10 216
LGB-11 216
LGB-12 216
* From left burner.

Part Number 550-141-807/0298 3
Flame Guardian WMBC-1A Electronic Pilot System – IRI
Figure 2
Q179 pilot burner assembly
Figure 3
Main flame sensor assembly
IInstallation – continued
LGB-A56
Locating Slot Igniter
Sensor Q179 Pilot
Burner
10-32 x 5/16“
Machine Screws(2)
Ground Leadwire:
Connect to WMBC
Panel Terminal G2
(Ground Terminal)
Pilot Mounting
Bracket
10-32 x 1/4“
Machine Screws (2)
Main Burner
(with Pilot
Mounting
Bracket)
Compression
Union
Sensor Lead
Burner Support Bar
Pilot Line Tubing
Igniter Lead
LGB-A85
Locating Slot
Flame
Sensor
6-32 x 5/16“ Type ”F”
Self Tapping Screws(2)
Ground Leadwire:
Connect to Main Flame
Proving Module
24 V (GND) terminal
Main Burner
(with Pilot
Mounting
Bracket)
Sensor Lead
Burner Support Bar
Flame Sensor
Mounting Bracket
10-32 x 5/16“
Machine Screws(2)

Part Number 550-141-807/02984
LGB (Series 2) — Control Supplement
1613 15
1718
18
14
12
11 10
9
7
6
5
4
3
2
1
Boiler Jacket
Vent to Outside
Atmosphere
Drip Leg Service Valve
9Second motorized gas valve w/ on/off actuator
1Manual main shut-off gas valve
2Low gas pressure switch
3Pilot manual shut-off valve
4Motorized gas valve w/ on/off actuator
5Pilot gas pressure regulator
6Normally open solenoid vent valve
7Pilot solenoid gas valve
8Test cock
10 Manual leak checking gas valve
11 Regulating diaphragm gas valve (two stage)
12 High gas pressure switch
13 Main flame sensor
14 Main burner with main flame sensor bracket
15 Pilot burner
16 Main burner with pilot burner bracket
18 Pipe flanges
17 Adapter, for N. O. vent valve
GAS PIPING DIAGRAM - LGB (Series 2)
IRI Gas Train
8
IInstallation – continued
Figure 4
IRI gas train schematic

Part Number 550-141-807/0298 5
Flame Guardian WMBC-1A Electronic Pilot System – IRI
1. Size gas piping considering:
a. Diameter and length of gas supply piping.
b. Number of fittings.
c. Maximum gas consumption (including any possible future expansion).
d. Allowable pressure drop from gas meter outlet to boiler. For pressure drops, see ANSI-Z223.1 – latest
edition.
2. Size natural gas piping from table below. Size piping to provide proper inlet pressure to gas valve when operating
at rated input.
a. Inlet gas pressure to manual main shutoff gas valve minimum 7” W.C. standard (5½” on special order) –
maximum 13”W.C.
b. If pressure to gas valve exceeds 13”W.C., install positive dead-end lockup gas pressure regulator up stream of
hand valve.
c. To obtain approximate cubic feet per hour, divide input (BTU/HR) by 1000.
3. Remove gas supply knockout disc from jacket panel.
4. Follow good piping practices.
5. Pipe joint compound (pipe dope) must be resistant to corrosive action of liquefied petroleum gases. Apply
sparingly only to male threads of pipe joints.
6. Install drip leg at inlet of gas connection to boiler. Where local utility requires, extend drip leg to floor.
7. Install ground joint union when required for servicing.
8. Support piping by hangers, not by boiler or its accessories.
9. Purge all air from supply piping.
10. Check all connections for leaks.
a. Close manual main shutoff valve during any pressure testing at less than 14.0 inches water column.
b. Disconnect boiler and gas controls from gas supply piping during any pressure test greater than 14.0 inches
water column.
11. Set gas pressure switches as follows or to local inspector’s requirements:
a. Low – 3.0” W.C. b. High – 14.0”W.C
II Gas piping
Do not check for gas leaks with an open flame – BUBBLE TEST. Failure to use bubble test or test for leaks can cause
severe personal injury, death or substantial property damage.
III Wiring
1. All wiring must be installed in accordance with the requirements of the National Electrical Code and any additional
national, state or local code requirements having jurisdiction. All wiring must be N.E.C. Class 1.
2. The boiler must be electrically grounded in accordance with the National Electrical Code,ANSI/NFPA No. 70-
latest edition. Use 105 °C. thermoplastic wire, or equivalent, if any of the original wire must be replaced (except
for pilot spark, sense and ground wires).
3. Supply wiring to the boiler must be No. 14 gauge or heavier. Install in conduit.
4. A separate electrical circuit with a fused disconnect switch (15 amp. recommended) should be used for the boiler.
For your safety,turn off electrical power supply before making any electrical connections to avoid possible electrical
shock hazard.
Table 2
Natural gas
supply pipe
sizing
PIPE
SIZE
10
’
20
’
30
’
40
’
50
’
75
’
100
’
150
’
1¼" 1,050 730 590 500 440 360 305 250
1½" 1,600 1,100 890 760 670 545 460 380
2" 3,050 2,100 1,650 1,450 1,270 1,020 870 710
2½" 4,800 3,300 2,700 2,300 2,000 1,650 1,400 1,130
3" 8,500 5,900 4,700 4,100 3,600 2,900 2,500 2,000
4" 17,500 12,000 9,700 8,300 7,400 6,000 5,100 4,100
* Include measured length of gas supply piping and allowance in feet for number and size of fittings.
PIPE LENGTH, FEET (NATURAL GAS CAPACITIES, LISTED IN MBH)
(Specific Gravity 0.60 @ Pressure Loss of 0.30" w.c.)

Part Number 550-141-807/02986
LGB (Series 2) — Control Supplement
Part Number 550-141-807/0298 7
Flame Guardian WMBC-1A Electronic Pilot System – IRI
Figure 5 — WMBC-1A panel wiring schematic

Part Number 550-141-807/02988
LGB (Series 2) — Control Supplement
Figure 6 — WMBC-1A panel wiring diagram – factory wiring

Part Number 550-141-807/0298 9
Flame Guardian WMBC-1A Electronic Pilot System – IRI
Figure 7 — WMBC-1A field wiring diagram

Part Number 550-141-807/029810
LGB (Series 2) — Control Supplement
IV Start-up
Low Fire Adjustment
1. Disable high fire by disconnecting the blue wire in the two-stage gas valve.
2. Connect manometer to gas manifold (manometer must be capable of measuring 0” to 14”
W.C.).
3. Turn on electrical power supply and gas supply to boiler.
4. Fire boiler, which will light off and remain on low fire.
5. While reading manometer, turn low fire adjustment screw clockwise (Figure 5) until pressure
reading is 1.2”W.C.
6. Turn off boiler.
7. Remove manometer from manifold and plug the tapping.
8. Reconnect the blue wire in the two-stage gas valve junction box.
9. Turn on electrical power supply and gas supply to boiler.
10. Follow operating instructions label on boiler to set boiler in operation.
Turn off electrical power supply and gas supply to boiler before making the following connections
and adjustment. Failure to do so can cause severe personal injury, death or substantial property
damage.
Turn off electrical power supply and gas supply to boiler before the following steps. Failure to
do so can cause severe personal injury, death or substantial property damage.
Figure 8
Low fire adjustment

Part Number 550-141-807/0298 11
Flame Guardian WMBC-1A Electronic Pilot System – IRI
VSequence of operation
1. Operating control begins startup sequence:
a. Limit control contacts are closed.
b. Purge timer is energized.
2. Flame safeguard control pilot circuit energizes after 2.0 seconds.
a. Pilot gas valve opens.
b. Ignition transformer energizes.
c. Yellow“pilot on” lamp lights.
d. Pilot ignition spark begins.
e. Pilot ignites.
f. Pilot flame proves.
3. Flame safeguard control energizes main flame circuit:
a. Blue“gas valve on”lamp lights.
b. Gas control train energizes.
c. Downstream gas valve opens to low-fire position.
d. Main burners ignite, operate at low fire.
4. Ignition transformer de-energizes after 10-second trial for ignition.
5. Pilot de-energizes after 10-second trial for main flame. Yellow“pilot on”lamp goes out.
6. Main flame sensor proves main burner operation at low fire.
7. Flame safeguard control energizes downstream gas valve to high-fire (through firing rate
control, when used):
a. Main burners operate at high fire.
b. Main burners operate at low fire when water temperature or pressure reaches setting of
firing rate control, when used.
8. Boiler shuts down when operating control satisfied.
9. Flame safeguard control lockout circuit energized if pilot is not proved during start-up or if
main flame is not proved during run sequence.
a. Flame safeguard control locks out on safety.
b. Red “alarm” lamp, alarm relay, and alarm bell energize. Silencing switch can shut off
alarm bell.
c. Alarm relay de-energizes purge timer.
d. Press reset button on flame safeguard control to permit normal start-up after correcting
lockout condition.
e. Normal start-up resumes after purge timer automatically resets (5 minute enforced
wait).