Weil-McLain WM97+70 Specifications download pdf (Page 49)

Part number 550-142-120/0113

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WM97+ gas-fired water boiler — Boiler Manual

Figure 56 WM97+155 Circulator zoning plus

optional DHW piping

System piping (continued)

Legend — Figure 56

1 WM97+155 boiler

2 Indirect water heater, when

used (for CWH installations,

refer to the Weil-McLain

CWH manual)

Relief valve, supplied with

boiler, ﬁeld piped — MUST

be piped to boiler supply

connection — see page 13 for

information

4 Relief valve piping to drain —

see page 39

5 DHW circulator

6 Isolation valves

8 System expansion tank, dia-

phragm type, when used

9 Air separator

10 Flow/check valves

11 Purge/drain valves (one drain

valve is supplied loose with

the boiler)

Boiler circulator, with inte-

gral ﬂow/check valve, factory

installed in boiler

Primary/secondary by-

pass valve — see page 41 for

information — OPEN: Boiler

connected as primary/second-

ary

20 Make-up water supply

23 Backﬂow preventer, when

used

24 Zone circulators

25 Pressure reducing valve, when

used

27 Quick-ﬁll valve, when used

DHW boiler water supply

connection, when used — see

page 13 for information

DHW boiler water return

connection, when used — see

page 13 for information

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

DHW refers to an indirect-ﬁred domestic hot

water storage tank. CWH refers to a Weil-

McLain Companion Water Heater.

CIRCULATOR zoning — primary/secondary

Internal P/S by-pass valve OPEN

WM97+155 only

The boiler primary/secondary by-pass valve MUST be open to

prevent excessive head caused by running the boiler circulator

and zone circulators in series.

See Figure 56.

1. OPEN the boiler internal primary/secondary by-pass valve.

2. Install a separate circulator for each zone. The boiler circulator

cannot

be used for a zone. It must remain in the boiler, as installed at the factory.

Expansion tank

1. Provide a system expansion tank following the guidelines on page 43.

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

connections to water heater boiler connections as shown. See the CWH

manual for CWH piping instructions.

2. DHW tank as a zone — A DHW tank can be piped as a zone (as in

Figure 60, page 53) if a DHW tank or CWH is

NOT connected to the

boiler. Wire the DHW circulator to boiler Zone 1. Set the boiler circula-

tor to ON in the DHW Settings menu.

3. Priority option — By default, the WM97+ control turns off space heat-

ing 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

NOT connecting a water heater, terminate the bottom connections

as shown in the inset on Figure 56.

Controlling the zones

1. The WM97+ control operates up to three zones (DHW or CWH plus

two space heating, or three space heating). Refer to Field wiring, begin-

ning on page 64, for instructions on wiring to circulators.

2. For more than three zones, use a Weil-McLain WMCR zone controller.

See suggested wiring in this manual.

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Weil-McLain WM97+70 Specifications Page 49

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