Weil-McLain WM97+70 Specifications download pdf (Page 40)

Part number 550-142-120/0113

WM97+ gas-fired water boiler — Boiler Manual

– 40 –

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 42). 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 43).

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 42 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 43 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 42 and Figure 43

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

1 2 ... 35 36 37 38 39 40 41 42 43 44 45 ... 135 136

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Weil-McLain WM97+70 Specifications Page 40

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