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Prepare remaining sections:
1. Follow “Prepare intermediate section” for
remaining intermediate and front sections:
a. Remove any grit from threads inside tapped
holes with clean rag.
Do not use petroleum-based cleaning or sealing
compounds in boiler system. Severe damage to
system components can result, causing
substantial property damage.
b. Install TI (Tankless Intermediate) and SI
(Supply Intermediate) sections (when used)
in order shown in “Section Arrangement
Table”.
c. Check each section for proper sealing rope
position before proceeding to next section.
Failure to position sealing rope properly can
cause boiler to not seal gas-tight. Gas-tight seal
prevents possible flue gas leakage and carbon
monoxide emissions, resulting in severe personal
injury or death.
d. Make sure bottom refractory blanket has
been installed per instructions on page 7.
Install burner mounting plate on front
section:
1. Install four 1/2" x 4-3/4" studs to secure burner
mounting plate to section:
a. Thread and lock together two nuts on
rounded end of stud. Thread flat end of stud
into one of four holes located around opening.
b. Remove nuts.
c. Repeat steps a and b for remaining studs.
2. Install burner mounting plate:
a. Apply 1/8" continuous bead of sealing rope
adhesive in groove around opening in section.
b. Position 1/2" sealing rope in groove. Overlap
ends at least one inch.
c. Install burner mounting plate. Use 1/2"
washers and nuts.
Install observation port assemblies
on front and back sections:
1. Install front observation port assembly:
a. Apply 1/8" continuous bead of sealing rope
adhesive in groove on observation port.
b. Position 3/8" sealing rope in groove.
Overlap ends at least one inch.
c. Secure assembly to section. Use 5/16-18 x
3/4" slotted head screws.
2. Repeat above steps for back observation port
assembly.
If using TI sections:
Install tankless heaters and gaskets or heater
cover plates and gaskets. Use 3/8" x 3/4" studs
and nuts.
Weil-McLain 78 Boiler For Gas, Light Oil, Gas/Light Oil Fired Burners
Assemble Block
3c
Part No. 550-141-705
8
W=Water, S=Steam, F=Front, TI=Tankless
Intermediate, I=Intermediate, SI=Supply
Intermediate for steam boilers, B=Back. “I”
sections can be substituted for “TI” sections.
If you would like to pressure-test block
assembly now, proceed to page 12.
Section Arrangement Table
Maximum Section Arrangement
Boiler No. of
(all heaters must be
Model Heaters on left side of boiler)
378 W&S 1 F-TI-B
478 W&S 1 F-TI-I-B
578 W&S 2 F-TI-I-TI-B
678 W&S 2 F-TI-I-TI-I-B
778 W&S 2 F-TI-I-TI-I-I-B
878 W&S 3 F-TI-I-TI-I-I-TI-B
978 W&S 3 F-TI-I-TI-I-TI-I-I-B
1078 W 3 F-TI-I-TI-I-I-TI-I-I-B
1078 S 3 F-TI-I-TI-SI-I-TI-I-I-B
1178 W 4 F-TI-I-TI-I-I-I-TI-I-TI-B
1178 S 4 F-TI-I-TI-I-SI-I-TI-I-TI-B
1278 W 4 F-TI-I-TI-I-I-I-I-TI-I-TI-B
1278 S 4 F-TI-I-TI-I-SI-I-I-TI-I-TI-B