Weil-McLain 88 Connect water boiler piping, General water piping information, Install piping

(note 1)

Weil-McLain 88 Water and steam boilers — Series 2 — for Gas, Light Oil, & Gas/Light Oil-Fired Burners

Connect water boiler piping

General water piping information

Figure 14 Water boiler piping, typical

1.System water supply and return piping should be installed and piping connections attached to boiler before erecting jacket or installing controls.

2.Do not pipe in through supply and out through return. This creates reverse water flow through boiler that must not be used.

3.When installing in a system in which return water temperature can 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.

1.Connect supply and return piping: a. Size according to tables below.

•For known flow rates or higher flow rate (less than 20°F temperature rise) through boiler, see Figure 15.

•For unknown flow rates, 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.

b.Locate circulator in supply piping.

c.For return piping, use full diameter pipe for 10 times that 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.

d.Install system blow-off (drain) valve in lowest part of return piping close to boiler. ASME minimum size requirements are given in Figure 17, page 15.

2.Install expansion tank:

a.Closed type – 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.

b.Diaphragm type – Refer to tank manufacturer's literature for location. Install automatic air vent in "K" tapping.

c.Connect cold water fill to expansion tank piping. 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.

d.Also shown are recommended valves and water meter, when used. Water meter will detect added make-up water, indicating leaks in system.

14

Figure 15 Recommended minimum pipe sizes for known flow rates

Water flow rate	Supply pipe size	Return pipe size
GPM	A	B
Up to 35	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.

Part No. 550-100-068/0308