Weil-McLain WM97+70 Manual page 58

WM97+ -
gas fired water boiler
Multiple boiler installations
Piping layout — typical piping for multiple WM97+ boilers,
Figure 65
with DHW storage heaters (4-boiler system)
(shown using WM97+155 boilers — adjust boiler
connections as required for other boiler models)
Legend — Figure 65
1 Flow/check valve (integral to each
boiler internal circulator)
2 Isolation valves (when used)
3 Caps
4 Easy-Fit® Manifold (supply) — layout
and size per page 55
5 Easy-Fit® Manifold (return) — layout
and size per page 55
6 Primary circulator
7 Expansion tank (diaphragm type)
8 System air eliminator
9 System automatic air vent
13 Cold water supply
17 Boiler circulator — circulates water
between boiler and Easy-Fit® Mani-
folds
18 System supply
19 System return
20 Boiler relief valve and discharge
piping, installed per WM97+ Boiler
Manual
– 58 –
— Boiler Manual
The boiler internal primary/secondary by-pass valve must be CLOSED for multiple boiler installations piped
as shown in this manual. This allows the boiler internal circulator to circulator water to and from the manifolds.
21 Indirect-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.
22 DHW boiler water supply, typical
23 DHW boiler water return, typical
24 DHW boiler-side circulators
25 DHW boiler-side supply Easy-Fit® Manifold
26 DHW boiler-side return Easy-Fit® Manifold
27 Flow/check valves (to prevent induced or gravity flow in heating
system or DHW piping)
28 Check valve to prevent heat migration in heating system
29 See water heater manual for DHW piping — The DHW piping must
also be manifolded together since the boiler-side piping is mani-
folded. If DHW heaters supply separate DHW circuits, provide an
individual circulator for each water heater, and control each circula-
tor by its water heater's aquastat.
32 Drain valves for DHW boiler water piping
(continued)
Flow rate
Suggested DHW
1 – 3.9 gpm
boiler-side pipe
sizing
(for max 0.04
3.9 – 7.1 gpm
feet head loss per foot of
7.1 – 16 gpm
total equivalent length,
TEL)
16 – 24 gpm
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 prior-
ity by disabling the heating system circulator any
time there is a DHW call for heat. The boiler circula-
tors, 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.
Size Flow rate Size
¾" 24 – 45 gpm 2"
1" 45 – 75 gpm 2½"
1¼" 75 - 140 gpm 3"
1½" 140 – 290 gpm 4"
This piping is suggested only. The
layout above should be controlled
Part number 550-142-085/0712