Weil-McLain WM97+110, Manual, Page: 38 / 132

Part number 550-142-085/0712
WM97+
gas
-
fired water boiler
— Boiler Manual
– 38 –
Internal water piping — WM97+70 and 110
Set primary/secondary by-pass valve
WM97+70 or 110 only
1. The primary/secondary by-pass valve (item 5 in the illustrations
at right) allows selecting whether the boiler is direct-connected or
primary/secondary connected to the system.
a. Close the valve for direct connection (Figure 38). Use this op-
tion ONLY if the system piping is connected per the instruc-
tions in this manual.
b. Open the valve for primary/secondary connection (Figure 39).
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 operate the boiler with the valve closed on a
system that is zoned with circulators or if the system has
a separate system circulator. This could cause the boiler
circulator to operate in series with external circulators,
causing possible excess pressure on valves and system
components.
Operate with the by-pass closed (using boiler circula-
tor for system flow)
ONLY
where shown on application
instructions in this manual.
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 property damage.
Figure 38 WM97+70/110
internal piping with by-
pass valve
CLOSED
(boiler circulator
provides system flow) — some
componensts omitted for clarity — see
legend below left
Figure 39
WM97+70/110
internal piping with by-
pass valve
OPEN
(primary/secondary
connection — separate system pump (or
zone pumps) must be supplied — some
componensts omitted for clarity — see
legend below left
Legend for Figure 38 and Figure 39
1 Heat exchanger
2 Return entrance to heat exchanger
3 Supply exit from heat exchanger
4 Boiler circulator — DO NOT RE-
MOVE OR RELOCATE!
5 Primary/secondary by-pass valve
— OPEN for primary/secondary
piping; CLOSED for direct connec-
tion
6 Supply connection to heating sys-
tem (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, if used — re-
quires separate external circulator
to provide flow for the DHW tank
9 Boiler water return connection from
DHW storage tank, if used