Weil-McLain WM97+100 Manual page 69

WM97+ Series 2
Field wiring
Low voltage wiring (24 VAC)
Make the following low-voltage connections, some of which depend
on your system and how the WM97+ control will be programmed.
The callouts below refer to Figure 79.
H
1. The WM97+ control provides inputs for up to three zones.
The WM97+ control default setting is for three space
heating zones. The control settings must be changed to
operate on DHW. If operating on space heating only, the
Zone 1 output can be used as described for Zone 2.
2. Control options require that DHW tanks be controlled from Zone 1
if domestic water priority is required.
3. ALWAYS connect DHW aquastat to Zone 1 input if domestic prior-
ity is required. This can be done if the DHW tank is piped to the
DHW connections out the bottom of the WM97+ or if the DHW
tank is piped as a separate zone in the system.
J
1. Use the Zone 2 input to:
a. Connect the thermostat for a space heating zone.
b. Connect end switch wire(s) (must be ISOLATED contacts) to
start boiler on a call for space heating.
c. Connect system control input for space heating call for heat
(ISOLATED contact only).
2. The WM97+ control will activate the 120VAC Zone 2 output if
the Zone 2 thermostat or input device calls for heat, after DHW
heating is satisfied.
K
1. Same as Zone 2. Zone 3 is not used for zone valve systems.
M
1. The WM97+ control provides programmable options if using an
outdoor temperature sensor. This sensor is supplied with the boiler.
2. Mount the outdoor sensor on an exterior wall, shielded from direct
sunlight or flow of heat or cooling from other sources. The wire out-
let on the sensor must be oriented DOWN to prevent water entry.
3. Connect the sensor leads to the ODT TEMP terminals, as shown
in the wiring diagrams. Thermostat wire can be used to connect
the sensor.
N
1. Connect isolated contacts of external limits across the MAN LIMIT
terminals to cause the WM97+ control to lock out (requiring
manual reset) if the limit opens. The limit must close and the con-
trol must be re-started using the procedure given in this manual.
P
1. Connect isolated contacts of external limits across the AUTO LIM-
IT terminals to cause the WM97+ control to shut down the boiler
on limit opening, then automatically restart after the limit closes.
R
1. The alarm contacts will close if the WM97+ control enters lockout.
Contacts will remain closed until the WM97+ control is reset.
2. Alarm contacts are isolated and are rated 1 amp at 24 VAC.
Part number 550-142-204/0117
-
GAS FIRED WATER BOILER
(continued)
— Boiler Manual
WM97+
connections (24VAC)
—
power to the thermostat circuits (H, J and
K in Figure 76) or attempt to supply 24 volts
for any other application.
connect any device to ZONE1 if
using
is dedicated to the water heater.
For thermostats that require a continuous
24-volt power source, connect the ther-
mostat power input to the "R-C 24VAC"
terminal of the lower voltage terminal strip.
— If using 3-wire zone valves,
use relays to provide dry contacts to the
WM97+ control thermostat connections.
The zone valve end switches of 3-wire valves
carry 24 VAC from the valve.
0.1 amps.
DHW heating is configured for direct pip-
ing to the bottom of the boiler. The DHW
circulator is powered from Zone 1 on a
call from the DHW aquastat (connected to
Zone 1 input). With this set-up, the boiler
circulator is NOT activated during DHW
heating. Zone 2 and Zone 3 are also NOT
activated during domestic priority heating
on Zone 1.
The factory default for space heating is de-
signed for finned-tube baseboard, and set
up to activate Zone 2 and Zone 3 on a call
for heat from the zone thermostats.
See instructions on the following pages
to adjust the WM97+ control settings to
match installation requirements.
input and output
supply 24-volt
unit. This circuit
—
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