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P/N 42-9470 11/07 Copyright 2007 Mestek, Inc.
Cast iron condensing boiler
Cast iron condensing boiler
— Installation and operation manual
IAR (Indoor Air Reset) wiring, when used
Wiring for typical zone controller
Heat Demand terminal connections — Th e end switch leads from the controller
must connect to the Heat Demand terminals on the electrical connection board as
shown in Figure A3.
IAR connections — See Figure A3 for typical wiring to the IAR inputs when using
a zone controller. For other applications, see the Control manual and Section 7 of
this manual.
Polarity
— Th e connections to the
IAR
positive terminals (
IAR +
)
must be to the same location on the zone valve as the thermostat wire,
as shown in Figure A3. Th e connections to the
IAR
negative terminals
(
IAR –
) must be from the zone controller’s 24VAC common terminal
as shown. Connecting the wires incorrectly can cause the transformer
to be shorted out and damaged.
Thermostat terminal connections:
Use a voltmeter to verify the
wiring is correct. Measure the voltage on the thermostat terminals
with the zone controller powered, BEFORE connecting any wires. Th
e
IAR positive terminal connections (
IAR +
) must be to the side of the
thermostat connections that have zero voltage.
DHW priority zone:
Most zone controllers will provide a priority
zone for connection to a DHW tank aquastat and circulator. Th
e priority
switch will turn off space heating when there is a DHW call. Read the
controller manufacturer’s instructions to determine which zone is set
up for priority operation.
•
•
Appendix A — suggested wiring
(continued)
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