Weil-McLain 88 - Manual (Page 17)

"OILER
17 Part No. 550-100-068/1009
Connect steam boiler piping
(continued)
Model 488 through 688 steam (1 riser) &IGURE
Improperly piped systems or undersized piping can
contribute to erratic boiler operation and possible boiler
or system damage. Piping system must be installed as
shown, using pipe sizes shown. Pipe sizes shown are for
two-pipe, pumped-return systems. Adjust pipe sizing
as needed when connecting to gravity-return systems.
Consult local Weil-McLain distributor or sales office
before installing alternate piping.
Steam boiler piping guidelines
-INIMUM
The boiler header must always be at least 
above the water line, as shown in all steam boiler piping
diagrams. Installing the pipe lower will result in increased
water carryover to the system, resulting in potential seri-
ous damage to system components and oxygen corrosion
due to excess make-up water.
(ARTFORD
You must install the system supply pipe between the equalizer 1.
elbow and the last boiler riser pipe connection to the header. This
assists in separating water from the steam as it turns upward into
the steam supply pipe.
Locate the top of the Hartford loop return nipple at least 4 inches
2.
below the water line, as shown.
Drawing legend & notes
(Figure 23 through Figure 26)
Riser pipes (one for each supply intermediate 
section)
Horizontal pipes needed to offset the header 
to allow for expansion and contraction of the
header
Steam supply must be located between last riser 
connection and equalizer elbow
Equalizer elbow — full size or reducing 
Equalizer pipe 
Close nipple at Hartford loop tee to reduce water 
hammer potential
Condensate return line (gravity or pumped) 
Minimum 4 inches between water line and top 
of Hartford loop return nipple
Boiler water line — all automatic water level 
controls must be set to maintain this level
Minimum 24 inches between water line and 
bottom of header