Weil-McLain WM97+110, Manual, Page: 39 / 132

Part number 550-142-085/0712
– 39 –
WM97+
gas
-
fired water boiler
— Boiler Manual
Internal water piping — WM97+155
Figure 40
WM97+155
internal piping with by-pass valve
OPEN
— (primary/secondary connection —
separate system pump (or zone pumps) must
be supplied — some components omitted for
clarity — see legend above right
Figure 41
WM97+155
internal piping with by-pass valve
CLOSED
—
Multiple-boiler applications ONLY
(boiler circulator provides flow to and from primary/
secondary manifolds) — some components
omitted for clarity — see legend above right
Set primary/secondary by-pass valve
WM97+155 only
The internal primary/secondary valve MUST
be OPEN for all applications except for instal-
lations with multiple WM97+ boilers, piped as
shown in this manual
.
Single-boiler installations require a separate system
circulator (or zone circulators). DO NOT attempt
to use the boiler internal circulator for system
circulation.
The boiler relief valve MUST be piped only to
the boiler supply connection
.
DO NOT pipe to
the return connection
. Install relief valve in ¾”
street elbow piped from boiler supply piping tee
(Figure 6, page 13). Pipe the relief valve only as
shown, in the location shown in Figure 6, page 13.
Failure to comply could prevent the relief valve
from properly protecting the boiler, resulting in
possible severe personal injury, death or substantial
property damage.
DO NOT
remove or relocate the boiler circulator.
DO NOT
attempt to change the boiler internal
piping.
Failure to comply with the above could result in
severe personal injury, death or substantial prop-
erty damage.
1. The primary/secondary by-pass valve (item 5 in the illus-
trations at right) is always left OPEN unless the boiler is
connected to a multiple-boiler manifold (and the internal
circulator provides flow only in the interconnecting piping
between the boiler and the manifold).
a. Single-boiler installation — Open the valve for primary/
secondary connection (Figure 40).
b. Multiple-boiler installation — Close the valve for direct
connection to the multiple-boiler manifold (Figure 41).
Legend for Figure 40 and Figure 41
1 Heat exchanger
2 Return entrance to heat ex-
changer
3 Supply exit from heat exchanger
4 Boiler circulator — DO NOT
REMOVE OR RELOCATE!
5 Primary/secondary by-pass
valve — OPEN for primary/
secondary piping; CLOSED for
direct connection (MBS only)
6 Supply connection to heating system
(P/T gauge and relief valve must
be mounted to supply as shown in
Figure 6, page 13)
7 Return connection from heating
system
8 Boiler water supply connection to
DHW storage tank, when used —
requires separate external circulator
to provide flow for the DHW tank
9 Boiler water return connection from
DHW storage tank, when used