Part number 550-142-058/0811
39
WM97+
gas
-
fired
water
boiler
—
Boiler Manual
Figure 43
Circulator zoning plus optional DHW
piping
CIRCULATOR zoning — primary/
secondary connection
(primary/secondary by-pass valve OPEN)
The boiler primary/secondary by-pass valve MUST be
open to prevent excessive head caused by running the
boiler circulator and zone circulators in series.
1. Connect boiler to system as shown in Figure 43 when circulator
zoning. The boiler circulator cannot be used for a zone. It must
remain in the boiler, as installed at the factory.
2. Install a separate circulator for each zone.
3. If using a supplementary closed-type expansion tank, connect
the expansion tank and make-up water piping as shown in Fig-
ure 38, page 35. DO NOT use a closed-type tank if connecting to
a PLUS water heater equipped with an automatic air vent.
4. When used, connect DHW (domestic hot water) piping from
boiler’s bottom connections to indirect storage water heater as
shown. If NOT connecting a DHW tank, terminate the connections
as shown in the inset on Figure 43. DHW can also be connected in
the system as a zone, as shown in Figure 45, page 41.
By default, the control module turns off space heating
to its Zone 2 and Zone 3 outputs during DHW heating
(if DHW input is set for priority). The boiler circulator
will turn off, preventing hot water from circulating to
the system (the control’s MAX ON TIME setting can be
used to limit how long this occurs). The boiler circula-
tor internal flow/check valve prevents circulation in the
boiler loop during DHW heating.
5. Controlling the circulators
a. The control module can control up to three zones (DHW +
2 space heating or 3 space heating). Refer to Field wiring, be-
ginning on page 45, for instructions on wiring to circulators.
b. For more than 3 zones (including DHW if used), use a Weil-
McLain WMCR zone controller. See suggested wiring in this
manual.
Install water piping
(continued)
Legend — Figure 43
1
WM97+ boiler
2
Indirect water heater, when
used
3
Relief valve, supplied with
boiler, field piped — MUST be
piped to boiler supply connec-
tion — see page 10 for informa-
tion
4
Relief valve piping to drain —
see page 33
5
DHW circulator
6
Isolation valves
8
Supplementary expansion tank,
diaphragm type, when used
9
Air separator
10
Flow/check valves
11
Purge/drain valves (one drain
valve is supplied loose with the
boiler)
12
Boiler circulator, with inte-
gral flow/check valve, factory
installed in boiler
14
Primary/secondary by-pass
valve — see page 34 for infor-
mation — OPEN: Boiler con-
nected as primary/secondary
20
Make-up water supply
23
Backflow preventer, when used
24
Zone circulators
25
Pressure reducing valve, when
used
26
Internal expansion tank,
diaphragm-type
27
Quick-fill valve, when used
28
DHW boiler water supply
connection, when used — see
page 11 for information
29
DHW boiler water return
connection, when used — see
page 11 for information
30
Pressure/temperature gauge,
supplied with boiler, field piped
31
Heating circuits
32
Additional heating circuits, if
any
= Items supplied with boiler
— all other items supplied by
installer
