Weil-McLain 94 Series Manual page 19

Boiler manual: • Installation
Connect steam boiler piping
Figure 24
Multiple Steam Boiler Piping Gravity Condensate Return
See page 18 for numbered
circle references.
Pipe as shown for gravity return systems, connecting point
A
A to the wet gravity return.
• For pumped-return systems, install boiler water level
control on each boiler with body mark at level indicated
in Figure 38, page 30. Provide at point A either:
• Separate feed pumps and check valves for each boiler,
or . . .
• Single feed pump, with separate solenoid valve for each
boiler.
For pumped-return systems, install a combination float and
B
thermostatic trap on each boiler to prevent flooding of one
boiler while other boiler is firing. Install trap in skim tapping.
Connect traps to condensate receiver.
Gravity-return systems are self-levelling if the wet returns are
piped to the common system wet return.
Install boiler piping as shown in the preceding pages of this
C
manual.
Part No. 550-110-275/1018
• Start-Up • Maintenance
D
E
F
G
• Parts
(continued)
Install stop valves per ASME code requirements.
• For pump-return systems, if using automatic steam
valves, use only slow-opening automatic valves. Use
a Weil-McLain Boiler Control System (such as a BCP
panel) to open each steam valve automatically before
firing burner.
Construct common supply drop header with pipe size at least
same size as largest boiler header size.
Use:
• A Weil-McLain Boiler Control System (such as a BCP
panel) with header-mounted pressure control(s) to
sequence boilers, or . . .
• A steam pressure controller.
Install drip line in common supply drop header.
• Gravity-return: Pipe drip line to wet return.
• Pumped-return: Use combination float and thermostatic
trap and drain to condensate receiver.
19