Part number 550-142-085/0712
WM97+
gas
-
fired
water
boiler
—
Boiler Manual
– 48 –
Figure 53
WM97+70/110
Typical radiant heating
system piping — circulator zoning
System piping
(continued)
Legend — Figure 53
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 37
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 38 for
information — OPEN: Boiler
connected as primary/second-
ary
20
Make-up water supply
22
High limit temperature con-
trol
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.
RADIANT HEATING — CIRCULATOR zoning
Internal P/S by-pass valve OPEN
WM97+70 or 110 only
See Figure 53.
1. The WM97+ boiler is ideal for use in radiant heating. The unique heat exchanger
design allows it to work well even in condensing mode. There is no need to regulate
boiler return water temperature in radiant heating applications.
2. Apply this configuration for typical radiant heating applications.
3. Size the system piping and circulators to provide the flow and pressure drop needed.
High limit in system piping
1. Add the recommended high limit control (Figure 53, item 22) to help ensure supply
water temperature will not exceed the maximum allowable for the radiant system.
2. Wire the limit control to either the manual reset or automatic reset external limit
circuit of the WM97+ control.
Supplementary expansion tank, if used
1. If using a supplementary closed-type expansion tank, connect the expansion tank
and make-up water piping as shown in Figure 43, page 40.
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 Fig-
ure 55, page 50) if a DHW tank or CWH is
NOT
connected to the boiler. Wire
the DHW circulator to boiler Zone 1. Set the boiler circulator to ON in the DHW
Settings menu.
3. Priority option — By default, the WM97+ control turns off space heating 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 53.
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, beginning on page 62, for
instructions on wiring to circulators.
2. For more than three zones, use a Weil-McLain WMCR zone controller. See sug-
gested wiring in this manual.
1. Supplementary expansion tank, if used
Summary of Contents for WM97+110
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