Weil-McLain WM97+ Manual page 40

WM97+ -
gas fired water boiler
Install water piping
RADIANT HEATING — CIRCULATOR
zoning — primary/secondary boiler
connection (primary/secondary by-pass
valve OPEN)
1. The WM97+ boiler is ideal for use in radiant heating. The WM97+
boiler's unique heat exchanger design allows it to work well even in
condensing mode. So there is no need to regulate boiler return water
temperature in radiant heating applications.
2. Connect boiler to system as shown in Figure 44 for typical radiant
heating applications. The primary/secondary piping shown ensures
the boiler loop will have sufficient flow. Size the system piping and
circulator to provide the flow and pressure drop needed for the
radiant system.
3. Adding the recommended high limit control (Figure 44, item 22) can
help ensure supply water temperature will not exceed the maximum
allowable for the radiant system. Wire this limit control in either the
manual reset or automatic reset external limit circuit of the control
module.
4. If using a supplementary closed-type expansion tank, connect
the expansion tank and make-up water piping as shown in Fig-
ure 38, page 35. DO NOT use a closed-type tank if connecting to
a PLUS water heater equipped with an automatic air vent.
5. When used, connect DHW (domestic hot water) piping from boiler's
bottom connections to indirect storage water heater as shown. If
NOT connecting a DHW tank, terminate the connections as shown
in the inset on Figure 44. DHW can also be connected in the system
as a zone as shown in Figure 45, page 41.
By default, the control module turns off space heating to its
Zone 2 and Zone 3 outputs during DHW heating (if DHW input
is set for priority). The boiler circulator will turn off, preventing
hot water from circulating to the system (the control's MAX ON
TIME setting can be used to limit how long this occurs). The
boiler circulator internal flow/check valve prevents circulation
in the boiler loop during DHW heating.
6. Controlling the circulators
a. The control module can control up to three zones (DHW + 2
space heating or 3 space heating). Refer to Field wiring, beginning
on page 45, for instructions on wiring to circulators.
b. For more than 3 zones (including DHW if used), use a Weil-
McLain WMCR zone controller. See suggested wiring in this
manual.
1
WM97+ boiler
2
Indirect water heater, when
used
3
Relief valve, supplied with
boiler, field piped — MUST be
piped to boiler supply connec-
tion — see page 10 for informa-
tion
4
Relief valve piping to drain —
see page 33
5
DHW circulator
6
Isolation valves
40
— Boiler Manual
(continued)
Legend — Figure 44
8
Supplementary expansion tank,
diaphragm type, when 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 34 for infor-
mation — OPEN: Boiler con-
nected as primary/secondary
Figure 44 Typical radiant heating system piping —
circulator zoning
20 Make-up water supply
22 High limit temperature control
23 Backflow preventer, when used
24 Zone circulators
25 Pressure reducing valve, when
used
26
Internal expansion tank,
diaphragm-type
27 Quick-fill valve, when used
28
DHW boiler water supply
connection, when used — see
page 11 for information
29
DHW boiler water return
connection, when used — see
page 11 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
Part number 550-142-058/0811