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•
When the thermostat calls for cooling, the
thermostat circuit between R and G is
completed.
•
The normally open contacts close, causing
the indoor blower motor to operate.
•
The thermostat circuit between R and Y is
also completed; this circuit closes the
contactor in the outdoor fan motor.
•
Thermostat circuits R and O, or R and B,
energizes the reversing valve, switching it to
the cooling position (depends on outdoor
HVAC unit).
•
The air handler blower will turn off 45
seconds after the thermostat stops calling
for cooling.
Control Board Located Inside Air Handler
Blower Door Safety Switch Circuit
•
The Blower Door Safety Switch circuit (across P4 and P1 connections shown above) must be
complete for all sequence of operations to take place.
•
During installation, use caution to not let the control board and other controls get wet.
Hydronic Air Handler Installation and Operation Manual
IMPORTANT
•
When the thermostat calls for heat, the
thermostat circuit between R and W is
completed, activating the hot water
circulating pump.
•
If a field-installed circulating pump is being
used, the control board can still be wired to
the pump directly or to an isolation valve
supplying hot water to the air handler using
the control board's 24V relay switch. A
similar 24V dry switching relay labeled TT
can be used to activate a boiler or water
heater valve.
•
A time delay of 60 seconds follows before
the thermostat circuit between R and G are
complete, activating the blower motor.
•
The thermostat circuit between R and W is
completed.
•
The air handler blower will turn off 30
seconds after the thermostat stops calling
for heating.
Heat Selection Pins
• E = Electric Heat (Not Applicable)
• HW = Hot Water Heater
(Jumper installed on HW)
Test Pins
(No Jumper Installed)
Jumper Selection Pins
(Jumper Installed in
OFF Position)
41
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