Weil-McLain WM97+70 Manual page 51

WM97+ -
gas fired water boiler
System piping
DHW as a zone — CIRCULATOR zoning
Internal P/S by-pass valve OPEN
WM97+155 only
DO NOT use this piping if the boiler is connected to a CWH
unit. The CWH unit requires priority and would prevent
priority operation of the system DHW unit.
The boiler internal 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 56.
1. OPEN the boiler internal primary/secondary by-pass valve.
2. Install a separate circulator for each zone. The boiler circulator can-
not be used for a zone. It must remain in the boiler, as installed at
the factory.
3. Install the DHW tank as a system zone. The DHW tank can be piped as
a zone ONLY if a DHW tank or CWH is NOT connected to the boiler.
4. Wire the DHW circulator to boiler Zone 1. Set the boiler circulator to
ON in the DHW Settings menu.
5. 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.
6. Terminate the bottom connections as shown in the inset on Figure 56
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.
Controlling the zones
1. The WM97+ control operates up to three zones (DHW plus two 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 suggested wiring in this manual.
WM97+155 boiler
1
Indirect water heater, when
2
used (for CWH installations,
refer to the Weil-McLain
CWH manual)
Relief valve, supplied with
3
boiler, field piped — MUST
be piped to boiler supply
connection — see page 13 for
information
Relief valve piping to drain —
4
see page 37
DHW circulator
5
Part number 550-142-085/0712
— Boiler Manual
(continued)
Legend — Figure 56
Isolation valves
6
System expansion tank, dia-
8
phragm type, when used
Air separator
9
10 Flow/check valves
11 Purge/drain valves (one drain
valve is supplied loose with
the boiler)
Boiler circulator, with inte-
12
gral flow/check valve, factory
installed in boiler
Primary/secondary by-
14
pass valve — see page 39 for
DHW refers to an indirect-fired domestic hot
water storage tank. CWH refers to a Weil-
McLain Companion Water Heater.
WM97+155 Circulator zoning with DHW
Figure 56
as a zone
information — OPEN: Boiler
connected as primary/second-
ary
20 Make-up water supply
23 Backflow preventer, when
used
24 Zone circulators
25 Pressure reducing valve, when
used
27 Quick-fill valve, when used
DHW boiler water supply
28
connection, when used — see
page 13 for information
DHW boiler water return
29
connection, when used — see
page 13 for information
Pressure/temperature
30
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
– 51 –