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HA-A - Wiring – Radiant & Air Handler HEATING (HA) & Air Handler COOLING (F)*
Our Air Handlers are equipped with a pump relay that is activate in heating call. When an external room
thermostat calls for heating it will activate a “W” heating call. This in turn will signal the fan coil to
optimize its speed for heating. Because the L and A3 are jumpered, the A3 (common) and A1 (L1)
connections will be energized at 120 Volts. This connection switch will send power directly the heating
pump and cause hot water to circulate through the internal heating coil.
In cooling mode, a “Y” call will be signaled causing the Air Handler to change to cooing mode and
optimized its fan speed for cooling. A separate cooling heat exchanger is used separate from the heating
HX. A Caleffi ZSR 101 Zone Relay is needed for the second cooling pump – Connect the Y1 and C to the C
and W thermostat terminals on the ZSR 101 board. On a Cooling call Y1 on the output of the air handler is
energized, this in turn will cause the relay contact to close turning on the cooling circulation pump.
Radiant heating is done in the same manner but attached to its own heating T-Stat. On a heating call the
R and W terminals close and cause the radiant circulation pump to activate. Note multiple Caleffi ZSR 101
zone relays can be used or a single zone relay with multiple zones can be purchased.
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