Weil-McLain Boiler installation manual 1Flow/check valve each boiler, inch

GAS-FIRED WATER BOILER — Installation Manual — Multiple-boiler Systems

Figure 10 Typical piping for multiple Ultra boilers, Weil-McLain Easy-Fit®Manifolds, and indirect water heaters

1Flow/check valve (each boiler)

2Isolation valves (when used)

3Caps

4Easy-Fit®Manifold (supply), sized per Fig. 1 or Fig. 2, page 6

5Easy-Fit®Manifold (return), sized per Fig. 1 or Fig. 2, page 6

6Primary circulator

7Expansion tank (diaphragm type)

8System air eliminator

9System automatic air vent

13Cold water supply

17Boiler circulator (each boiler)

18System supply

19System return

20Boiler relief valve and discharge piping, installed per Ultra Boiler Manual

21Indirect-fired storage water heaters (Weil- McLain PLUS Line shown) — Example is shown with reverse-return boiler-side piping using a single circulator. Alternate: each water heater could have its own circulator.

22Boiler water inlet

23Boiler water outlet

24DHW boiler-side circulator

Suggested DHW boiler-side pipe sizing (based on 500 milinch per foot head loss in piping):

0 – 7 gpm		1 inch
7 – 16 gpm		1¼ inch
16	– 24 gpm	1½ inch
24	– 45 gpm	2 inch
45	– 75 gpm	2½ inch
75	–140 gpm	3 inch
140 – 290 gpm		4 inch

25DHW boiler-side supply Easy-Fit®Manifold

26DHW boiler-side return Easy-Fit®Manifold

27Flow/check valves (to prevent induced or gravity flow in heating system or DHW piping)

28Check valve to prevent heat migration in heating system

29See water heater manual for DHW piping — The DHW piping must also be manifolded together since the boiler-side piping is manifolded. If DHW heaters supply separate DHW circuits, provide an individual circulator for each water heater, and control each circulator by its water heater’s aquastat.

This piping is suggested only. The layout above should be controlled with a boiler sequencing panel that provides DHW operation as well. Wire the heating system circulator to operate only on call for heat. Alternatively, use the boiler sequencing panel to provide domestic priority by disabling the heating system circulator any time there is a DHW call for heat. The boiler circulators, item 17, must operate on any call for heat, whether heating system or DHW. Offset the DHW boiler-side supply and return manifolds as shown so the total run of pipe and fittings to each of the water heaters is approximately equal.

Part number 550-101-232/0703 11