Specifications

Part number 550-142-120/0113
WM97+ gas-fired water boiler — Boiler Manual
– 48 –
System piping (continued)
Legend — Figure 55
1 WM97+70 or 110 boiler
2 Indirect water heater, if used
(for CWH installations, refer
to the Weil-McLain CWH
manual)
3
Relief valve, supplied with
boiler, field piped — MUST
be piped to boiler supply
connection — see page 13 for
information
4 Relief valve piping to drain —
see page 39
5 DHW circulator
6 Isolation valves
8 Supplementary expansion
tank, diaphragm type, if 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 40 for
information — OPEN: Boiler
connected as primary/sec-
ondary
20 Make-up water supply
23 Backflow preventer, if used
24 Zone circulators
25 Pressure reducing valve, if
used
26
Internal expansion tank,
diaphragm-type
27 Quick-fill valve, if used
28
DHW boiler water supply
connection, when used — see
page 13 for information
29
DHW boiler water return
connection, when used — see
page 13 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
DHW refers to an indirect-fired domestic hot
water storage tank. CWH refers to a Weil-
McLain Companion Water Heater.
Figure 55 WM97+70/110 Circulator zoning plus
optional DHW piping
CIRCULATOR zoning — primary/secondary
Internal P/S by-pass valve OPEN
WM97+155 only
CIRCULATOR zoning — primary/secondary
Internal P/S by-pass valve OPEN
WM97+70 or 110 only
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.
See Figure 55.
1. OPEN the boiler internal primary/secondary by-pass valve.
2. Install a separate circulator for each zone. The boiler circulator
cannot
be used for a zone. It must remain in the boiler, as installed at the factory.
Supplementary expansion tank, if used
1. If using a supplementary closed-type expansion tank, connect the ex-
pansion tank and make-up water piping as shown in Figure 47, page 42.
2. DO NOT use a closed-type tank if connecting to a water heater that is
equipped with an automatic air vent.
DHW or CWH, if used —
1. DHW or CWH direct connection — Pipe from the boiler’s bottom
connections to water heater boiler connections as shown. See the CWH
manual for CWH piping instructions.
2. DHW tank as a zone — A DHW tank can be piped as a zone (as in
Figure 59, page 52) if a DHW tank or CWH is
NOT connected to the
boiler. Wire the DHW circulator to boiler Zone 1. Set the boiler circula-
tor to ON in the DHW Settings menu.
3. Priority option — By default, the WM97+ control turns off space heat-
ing to its Zone 2 and Zone 3 outputs during domestic water heating on
Zone 1. The MAX ON TIME setting can be adjusted to limit how long
this occurs. Set the MAX ON TIME to “0” to disable domestic priority.
4. If
NOT connecting a water heater, terminate the bottom connections
as shown in the inset on Figure 55.
Controlling the zones
1. The WM97+ control operates up to three zones (DHW or CWH plus
two space heating, or three space heating). Refer to Field wiring, begin-
ning on page 64, for instructions on wiring to circulators.
2. For more than three zones, use a Weil-McLain WMCR zone controller.
See suggested wiring in this manual.