Part number 550-142-085/0712
– 53 –
WM97+
gas
-
fired
water
boiler
—
Boiler Manual
Figure 58
WM97+155
Chilled water system plus
optional DHW piping
System piping
(continued)
Legend — Figure 58
1
WM97+155 boiler
2
Indirect water heater, when
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
7
System circulator
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
13
Zone valves
14
Primary/secondary by-
pass valve — see page 39 for
information — OPEN: Boiler
connected as primary/second-
ary
15
System expansion tank, closed
type, when used (some chiller
systems may use a diaphragm
type expansion tank)
16
Water chiller
17
Check valve
18
Y-strainer
19
Balancing valve
20
Make-up water supply
21
By-pass pressure regulator,
RECOMMENDED for zone
valve systems unless other
provision is made
23
Backflow preventer, when
used
25
Pressure reducing valve, when
used
27
Quick-fill valve, when 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.
WATER CHILLER systems — ZONE VALVES
Internal P/S by-pass valve OPEN
WM97+155 only
See Figure 58
1.
OPEN
the boiler internal primary/secondary by-pass valve.
2. The chiller must be piped in parallel with the boiler.
3. Use appropriate valves to prevent chilled medium from entering boiler.
4. Circulator zoning option — The space heating system can be zoned with circula-
tors if a separate circulator is supplied for the chilled water loop. 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.
If antifreeze is used in the system, consider the effects of antifreeze on
circulator sizing and DHW performance. Some local codes may require
double-wall DHW heat exchanger design. Use only the antifreeze listed
by Weil-McLain for use with this boiler. See page 86 for details.
Chilled medium, if used, is piped in parallel with heating boiler as
shown in Figure 57. Use appropriate valves to prevent chilled medium
from entering boiler. If boiler is connected to heating coils located in air
handling units where they can be exposed to refrigerated air, use flow
control valves or other automatic means to prevent gravity circulation
during cooling cycle.
Expansion tank
1. Provide a system expansion tank following the guidelines on page 41.
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 56, page 51)
if a DHW tank or CWH is
NOT
connected to the boiler. To provide DHW priority
operation in this case, a Weil-McLain WMZV must be used.
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 58.
Controlling the zones
1. The WM97+ control can be set up to operate on space heating only or on space
heating plus DHW or CWH. Refer to Field wiring, beginning on page 62, for
instructions on wiring to zone valves.
2. The boiler and zone valves can also be operated by a Weil-McLain WMZV
zone controller.
Use isolation relays if connected 3-wire zone valve end
switches to the WM97+ control inputs.
Connect zone valve end switches to ZONE 2 input.
Connect system circulator to CIRC 2 output.
Summary of Contents for WM97+110
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