Weil-McLain WM97+70 Manual page 44

WM97+ -
gas fired water boiler
System piping
ZONE VALVE zoning — primary/secondary
Internal P/S by-pass valve OPEN
WM97+70 or 110 only
The boiler primary/secondary by-pass valve
to prevent excessive head caused by running the boiler circula-
tor and system circulator in series.
See Figure 49.
1. This configuration is for WM97+70 or 110 zone valve systems that need
more flow than the boiler's circulator can provide (see page 43 for infor-
mation).
the boiler internal primary/secondary by-pass valve.
2. OPEN
3. Install a system circulator (supplied by installer) as shown.
4. A benefit of primary/secondary piping is that it does not apply the head of
the boiler circulator to the system zone valves.
Supplementary expansion tank, if used
1. Connect the supplementary 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 con-
nections to water heater boiler connections as shown. See CWH manual
for CWH piping instructions.
2. DHW as a zone — A DHW tank can be piped as a zone if a DHW tank or
CWH is connected to the boiler. To provide DHW priority operation
NOT
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 connecting a water heater, terminate the bottom connections as
NOT
shown in the inset on Figure 49.
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.
WM97+70 or 110 boiler
1
Indirect water heater, if used
2
(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
Isolation valves
6
System circulator
7
– 44 –
— Boiler Manual
(continued)
MUST be OPEN
Legend — Figure 49
Supplementary expansion
8
tank, diaphragm type, if 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
13 Zone valves
Primary/secondary by-
14
pass valve — see page 38 for
information — OPEN: Boiler
connected as primary/second-
DHW refers to an indirect-fired domestic hot
water storage tank. CWH refers to a Weil-
McLain Companion Water Heater.
WM97+70/110 Zone valve zoning —
Figure 49
primary/secondary connection —
a system circulator is required
Connect zone valve end switches to ZONE 2 input.
Connect system circulator to CIRC 2 output.
Use isolation relays if connected 3-wire zone valve end
switches to the WM97+ control inputs.
ary
20 Make-up water supply
21 By-pass pressure regulator,
RECOMMENDED for zone
valve systems unless other
provision is made
23 Backflow preventer, if used
25 Pressure reducing valve, if
used
Internal expansion tank,
26
diaphragm-type
27 Quick-fill valve, if 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
Part number 550-142-085/0712