Weil-McLain LGB-20 Use and maintenance manual

Contents
I. Installation .................... 2
II. Gas piping..................... 4
III. Water and steam trim
components.................... 5
IV. Wiring............................ 5
Sequence of operation ......8
Wiring procedure ...............8
V. Leak test procedure ... 10
VI. Operating instructions 11
VII. Parts list ...................... 12
These terms are used throughout this
manual to bring attention to the presence
of hazards of various risk levels or to
important information concerning the life
of the product.
LGB
CSD-1 Control System
Control Supplement
LGB-6 to LGB-20 Series 2
– Natural gas
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/ser-
vice technician. Read these instructions completely before beginning the
installation. Failure to follow these instructions can cause severe personal
injury, death or substantial property damage.
Gas–fired boiler
Part Number 550-141-815/1010

LGB-6 to LGB-20 Series 2 – Control Supplement
2Part Number 550-141-815/1010
Boiler
Number
Flame Sensor * Pilot Burner * Boiler
Number
Flame Sensor * Pilot Burner *
No. 1 No. 2 No. 1 No. 2 No. 1 No. 2 No. 1 No. 2
LGB-6 2 --- 9 --- LGB-14 216 13 25
LGB-7 2 --- 11 --- LGB-15 216 13 27
LGB-8 2 --- 13 --- LGB-16 218 15 29
LGB-9 2 --- 15 --- LGB-17 218 15 31
LGB-10 2 --- 16 --- LGB-18 220 16 33
LGB-11 2 --- 16 --- LGB-19 220 16 34
LGB-12 2 --- 16 --- LGB-20 222 16 36
LGB-13 2 1`4 11 23
* From left burner.
Boiler
Number
7.00”
W.C.
Carton
Inlet Pipe Size 5.00”
W.C.
Carton
Inlet Pipe Size
Left Base Right Base Left Base Right Base
LGB-6 A and B 1” --- A and B 1-¼” ---
LGB-7 A and B 1” --- A and B 1-¼” ---
LGB-8 C and D 1” --- C and D 1-¼” ---
LGB-9 C and D 1” --- C and D 1-¼” ---
LGB-10 E, F and G 1-¼” --- E 1-½” ---
LGB-11 E, F and G 1-¼” --- F and G 2” ---
LGB-12 E, F and G 1-¼” --- F and G 2” ---
LGB-13 H 1” 1” H 1-¼” 1-¼”
LGB-14 I 1” 1” I 1-¼” 1-¼”
LGB-15 J 1” 1” J 1-¼” 1-¼”
LGB-16 J 1” 1” J 1-¼” 1-¼”
LGB-17 J 1” 1” J 1-¼” 1-¼”
LGB-18 K 1-¼” 1” K 1-½” 1-¼”
LGB-19 L 1-¼” 1-¼” M 1-½” 1-½”
LGB-20 L 1-¼” 1-¼” N 2” 1-½”
IInstallation
1. Assemble pilot burner and flame sensor to main burners with pilot brackets. See Figures
1 and 2 (page 3). Install ground wiring as shown in Figures 1 and 2 (page 3).
2. Reinstall burner assemblies. See Table 1, below for pilot burner and flame sensor loca-
tions.
3. Install gas controls and ignition control panel(s) as shown in Table 2, below and Figure
6 (page 12).
Table 1
Pilot burner and flame sensor
locations
Table 2
Gas control arrangement

CSD-1 Control System - Natural gas
3
Part Number 550-141-815/1010
Figure 1
Pilot burner assembly, typical
IInstallation – continued
Figure 2
Main flame sensor assembly

LGB-6 to LGB-20 Series 2 – Control Supplement
4Part Number 550-141-815/1010
II Gas piping
Table 3
Gas pipe sizing - natural gas
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.
1. Size natural gas piping from Table 3, below. Size piping to provide proper inlet pressure
to gas valve when operating at rated input.
a. Inlet gas pressure to manual main shut-off gas valve —
minimum 7” W.C. standard (5” W.C. on special order) – maximum 13” W.C.
b. If pressure to gas valve exceeds 13” W.C., install 100% lock-up gas pressure
regulator upstream of hand valve.
c. To obtain approximate cubic feet per hour, divide input (Btu/hr) by 1000.
2. 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 to boiler. For pressure drops, see ANSI
Z223.1. – latest edition.
3. Remove knockout disc from jacket panel through which gas supply will be piped.
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 ends of pipe joints.
6. Install drip leg at inlet of gas connection to boiler. Where local code/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. Before operating boiler, check boiler and its gas connections for leaks.
a. Close manual main shut-off valve during any pressure testing at less than 13” W.C.
b. Disconnect boiler and gas valve from gas supply piping during any pressure test
greater than 13” W.C.
Pipe
size
*Pipe length, in feet (Natural Gas capacities listed in MBH)
(Specific gravity 0.60 @ Pressure Loss of 0.30" W.C.)
10 20 30 40 50 75 100 150
1-¼” 1,050 730 590 500 440 360 305 250
1-½” 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
2-½” 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.

CSD-1 Control System - Natural gas
5
Part Number 550-141-815/1010
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 external to boiler jacket 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 original wire must be replaced (except for pilot spark, sense and ground wires).
3. Wiring to 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.
5. Refer to wiring diagrams, Figure 3 (pages 6 and 7) and Figure 5 (page 9). See section,
“Wiring Procedure” on page 8.
6. Figure 5 on page 9 is the Field Wiring Diagram. See Figure 3, pages 6 and 7, for the
schematic and ladder wiring diagrams.
IV Wiring
For your safety, turn off electrical power supply before making any electrical
connections to avoid possible electrical shock hazard.
1. Install water or steam trim components as required by CSD-1 latest edition. See the
boiler manual for tapping locations.
a. Water boilers require:
s AMANUALRESETHIGHTEMPERATURELIMITCONTROLINADDITIONTOTHESTANDARD
automatic reset limit control.
s AMANUALRESETLOWWATERCUTOFF
b. Steam boilers require:
s AMANUALRESETHIGHPRESSURELIMITCONTROLINADDITIONTOTHESTANDARDAUTOMATIC
reset limit control.
s AMANUALRESETLOWWATERCUTOFFINADDITIONTOTHESTANDARDAUTOMATICRESETLOW
water cutoff.
III Water and steam trim components

LGB-6 to LGB-20 Series 2 – Control Supplement
6Part Number 550-141-815/1010

CSD-1 Control System - Natural gas
7
Part Number 550-141-815/1010
Figure 3
Wiring diagram

LGB-6 to LGB-20 Series 2 – Control Supplement
8Part Number 550-141-815/1010
IV Wiring - continued
1. Determine right or left electrical supply wiring.
2. Attach electrical junction box(es) to inside jacket end
panel. Screws and nuts are provided. For dual base
boilers, use offset nipples (provided) to connect junction
boxes together (as at right), then hang junction boxes
by screwing top box to boiler jacket. See Figure 4.
3. Attach control transformer(s) to junction box(es).
4. Drill 1/8” hole in interior jacket panel midway between
ignition control panel and left jacket panel. Mount wire
support clip using sheet metal screw (furnished).
5. Complete wiring per diagrams, Figure 3 (pages 6 and
7) and Figure 5 (page 9). Terminate at secondary gas
valve in valve junction box with wirenuts and strain
relief provided.
Wiring procedure
1. Operating control begins startup sequence.
a. Limit control contacts are closed.
2. Pilot proving module energized.
a. Pilot solenoid opens.
b. Pilot ignition spark begins.
c. Pilot ignites.
d. Pilot proves.
Sequence of operation
On failure to sense pilot flame, the pilot-proving module will wait 5
minutes, then retry for ignition. Upon 2 consecutive pilot flame failures,
the control will lockout and illuminate the red lockout light.
On failure to sense main flame, the main flame-proving module will
lockout and illuminate the red lockout light.
If the boiler locks out, the alarm contacts on the terminal strip (terminals
A1 and A2) close. These contacts are rated to 15 amps, 250 V. To reset
the boiler, push the red lockout button.
“Hot” side of line voltage to boiler
must be wired directly to limit
circuit, then fed to transformer
primary(ies).
Dual Base: “R” terminal of
secondaries are to supply power to
bases independently of each other.
Do not wire “R” terminals together.
Figure 4
Junction box assembly
dual base boilers
f. Main burners increase to high fire.
4. For dual base assembly - operating control energizes controls for each base assembly at the
same time. See steps 1 through 3 above.
5. Boiler shuts down when operating control satisfied.
3. Main flame proving module energized from pilot proving module.
a. Secondary gas valve opens.
b. Main gas valve opens to low fire position.
c. Main burners ignite at low fire.
d. Main flame sensor proves low fire carryover.
e. Main gas valve opens to high fire position.
6. Install pilot proving and main flame proving ground
connections as shown in Figures 1 and 2 and wiring
diagram. Route wires through wire support clip.

CSD-1 Control System - Natural gas
9
Part Number 550-141-815/1010
Figure 5
Field wiring diagram

LGB-6 to LGB-20 Series 2 – Control Supplement
10 Part Number 550-141-815/1010
1. Remove red (MV) and blue (PV) wires from main gas valve.
2. Close main test firing valve attached to the manifold.
3. Check that both leak test valves are closed and remove plugs.
4. Attach manometer to first leak test valve.
5. Open first leak test valve and check for pressure.
6. Close first leak test valve and remove manometer.
7. Attach manometer to second leak test valve.
8. Apply call for heat to boiler.
9. Check that electronic pilot proves.
10. Open second leak test valve and check for pressure.
11. Close second leak test valve and remove manometer.
12. Remove call for heat to boiler.
13. Reinstall plugs on leak test valves.
14. Connect wiring to main gas valve.
15. Open main test firing valve attached to the manifold.
When checking for pressure at the leak test valves, any small pressure
reading is normal. If the pressure continues to increase after opening the
leak test valve, the upstream valve is leaking and should be replaced.
VLeak test procedure

CSD-1 Control System - Natural gas
11
Part Number 550-141-815/1010
Operating instructions
VI
This document is intended only as a supplement to the LGB Gas-Fired
Boiler Manual. Follow all instructions in the Manual, including those
regarding start-up (found in Section VIII, “Placing boiler in operation”).
A. This boiler is equipped with an ignition device which automatically
lights the pilot. Do not try to light the pilot by hand.
B. BEFORE OPERATING, smell all around the boiler area for gas. Be
sure to smell next to the floor because some gas is heavier than air
and will settle on the floor.
WHAT TO DO IF YOU SMELL GAS
s $ONOTTRYTOLIGHTANYAPPLIANCE
s $ONOTTOUCHANYELECTRICSWITCHDONOTUSEANYPHONEIN
your building.
s )MMEDIATELYCALLYOURGASSUPPLIERFROMANEIGHBORSPHONE
&OLLOWTHEGASSUPPLIERSINSTRUCTIONS
s )FYOUCANNOTREACHYOURGASSUPPLIERCALLTHElREDEPARTMENT
C. Do not use this appliance if any part has been under water.
Immediately call a qualified service technician to inspect the
appliance and to replace any part of the control system and any gas
control, which has been under water.
Starting boiler 1. STOP! Read the safety information above.
2. Set the Operating control to lowest setting.
3. Turn off all electrical power to the appliance.
4. Remove Front panel.
5. This appliance is also equipped with an ignition device which automatically lights the
second pilot. Do not try to light this pilot by hand.
6. Close the Pilot shut-off valve connected to the Manual main shut-off valve. Close the
Manual main shut-off valve.
7. Wait five (5) minutes to clear out any gas. Then smell for gas, including near the floor.
)FYOUSMELLGAS34/0&OLLOWh"vINTHESAFETYINFORMATIONABOVE)FYOUDONTSMELL
gas, go to the next step.
8. Open the Pilot shut-off valve. Open the Manual main shut-off valve.
9. Turn on all electric power to the appliance.
10. Set Operating control to desired setting.
11. If the appliance will not operate, turn off gas to the boiler by closing the Pilot shut-off
valve and the Manual main shut-off valve. Turn off all electrical power. Call your service
technician or gas supplier.
12. Replace Front panel.

LGB-6 to LGB-20 Series 2 – Control Supplement
12 Part Number 550-141-815/1010
VII Parts
list
Figure 6