Weil-McLain 88 - Manual (Page 14)

Weil-McLain 88 Water and steam boilers — Series 2 — for Gas, Light Oil, & Gas/Light Oil-Fired Burners
14 Part No. 550-100-068/1009
Connect water boiler piping
General water piping information
System water supply and return piping should be installed and 1.
piping connections attached to boiler before erecting jacket or
installing controls.
Do not pipe in through supply and out through return. This creates 2.
reverse water flow through boiler that must not be used.
When installing in a system in which return water temperature can 3.
drop below 140°F, apply the by-pass piping with by-pass pump as
shown in .
Install piping
Install piping as shown in Figure 14, page 14 and Figure 18, page 15
(if applicable) for single boilers. For multiple boilers, see Fig-
ure 19, page 15.
Improperly piped systems or undersized piping can
contribute to erratic boiler operation and possible boiler
or system damage.
Connect supply and return piping: 1.
Size according to tables below. a.
For s KNOWN (less than 20°F
temperature rise) through boiler, see Figure 15.
For s UNKNOWN , size piping per Figure 17,
page page 15, using 20°F temperature rise through
boiler.
Flow at higher rates than shown in the tables in this
manual for given pipe sizes can damage the boiler, caus-
ing substantial property damage.
Locate circulator in supply piping. b.
For return piping, use full diameter pipe for 10 times that c.
diameter before making any reduction. For example, a 4-inch
return should not be reduced any closer to boiler return tap-
ping than 40 inches.
Install system blow-off (drain) valve in lowest part of return d.
piping close to boiler. ASME minimum size requirements are
given in Figure 17, page 15.
Install expansion tank: 2.
#LOSED a. – connect to 1" tapping "K" (see page 11). Use
1" NPT piping. Any horizontal piping must pitch up toward
tank at least 1 inch per each 5 feet of piping.
$IAPHRAGM b. – Refer to tank manufacturer's literature for
location. Install automatic air vent in "K" tapping.
Connect cold water fill to expansion tank piping. c. Figure 14
shows typical piping when using a closed type tank. Connect
to the same location as the expansion tank connects to the
system when using a diaphragm type tank.
Also shown are recommended valves and water meter, when d.
used. Water meter will detect added make-up water, indicating
leaks in system.
Water boiler piping, typical &IGURE
Recommended minimum pipe sizes for &IGURE
known flow rates (note 1)
7ATER
'0-
3UPPLY
A
2ETURN
B
5P 2" 2"
36–50 2½" 2½"
51–77 3" 3"
78–142 4" 4"
143–237 5" 5"
238–404 6" (note 2) 6"
Note 1 High temperature rise through boiler is permissible when boiler
piping connections are sized per this table. Intermittent
flow at high velocities may damage any boiler.
Note 2 6-inch piping requires nipples and 5" x 6" reducing couplings
(provided with 1288 through 1888 boilers only). The total
pressure drop through the 1888 boiler using the nipple and
reducing coupling will not exceed ¼ PSI. For smaller boilers, the
pressure drop will be less.