Weil-McLain SERIES 2 LGB-7 - Manual (Page 7)

Part Number 550-141-797/0798 8
LGB-6 to LGB-23 Series 2 – Control Supplement
Wiring Procedure
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 juction boxes together, 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 wiring diagram, Figure 3,
pages 6 and 7. Terminate at secondary gas valve in
valve junction box with wirenuts and strain relief
provided.
6. Install pilot proving and main flame proving
ground connections as shown in Figures 1, 2 and
3. Route wires through wire support clip.
7. Canada only - attach chain between junction
box(es) and transformer with S-hooks.
Figure 4
Junction box assembly
dual base boilers
“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.
Sequence of operation 1. Operating control begins start-up 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.
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.
f.
Main burners increase to high fire.
4. Dual base assembly (LGB-13 through LGB-23) - operating control energizes the controls
for both base assemblies at the same time. See steps 1 through 3 above.
5. Boiler shuts down when the operating control is satisfied.
On failure to sense pilot flame or main flame, control will wait 5 minutes
then retry for ignition.