Rinnai 37AHB SERIES - Manual (Page 24)

24 Rinnai Corporation Hydronic Furnace (37AHB) Manual
Sequence of Operation
SEQUENCE OF OPERATION:
NOTE: Furnace control must be grounded for proper
operation; control is grounded through green
wire routed to control box screw.
STANDBY MODE:
All control outputs are off and the control is waiting for
a thermostat demand. The control initiates action
when a thermostat call is received.
COOLING MODE:
Single-Stage Air-Conditioning (A/C) Cooling
Demand:
When the thermostat calls for cooling (Y), the control
energizes the COOL_HI blower tap after a 1 second
on delay period.
When the thermostat removes the call for cooling (Y),
the control de-energizes the COOL_HI blower tap after
a cooling off delay period of 30 seconds.
A call for cooling has priority over a thermostat blower
demand.
If a call for heat (W) exists with a call for cooling, the
call for heat shall proceed as normal except the blower
remains energized on the COOL_HI speed tap. If the
call for cool goes away while a call for heat exists, the
cooling off delay is canceled and the blower operation
reverts to the heat cycle.
Two-Stage A/C Cooling Demand:
When the thermostat calls for cooling (Y), the control
waits for a 1 second cooling on delay period and
energizes the COOL_LO blower tap. If a 2
nd stage
cooling (Y2) call is sensed, the control de-energizes
the COOL_LO blower tap and energizes the COOL_HI
blower tap after a 1 second delay.
When the thermostat removes the call for 2nd stage
cooling (Y2), the control de-energizes the COOL_HI
blower tap and energizes the COOL_LO blower tap.
When the thermostat removes the call for cooling (Y),
the control de-energizes the COOL_LO blower tap
after a cooling off delay period of 30 seconds.
If a call for heat (W) exists with a call for 2nd stage
cooling, the call for heat shall proceed as normal
except the blower remains energized on the COOL_HI
speed. If the call for cool goes away while a call for
heat exists, the cooling off delay is canceled and the
blower operation reverts to the heat cycle.
Single-Stage Heat-Pump (HP) Cooling Demand:
When the thermostat calls for cooling (Y and O), the
control waits for the 1 second cooling on delay period
and energizes the COOL_HI blower tap.
When the thermostat removes the call for cooling (Y
and O), the control de-energizes the COOL_HI blower
tap after a cooling off delay period of 30 seconds.
A call for cooling has priority over a thermostat blower
demand.
If a call for emergency heat (W) exists with a call for
cooling, the call for heat shall proceed as normal
except the blower remains energized on the COOL_HI
speed tap. If the call for cool goes away while a call
for emergency heat exists, the cooling off delay is
canceled and the blower operation reverts to the heat
cycle.
Two-Stage HP Cooling Demand:
When the thermostat calls for cooling (Y and O), the
control waits for the 1 second cooling on delay period
and energizes the COOL_LO blower tap. If a second
stage cooling (Y2) call is sensed, the control de-
energizes the COOL_LO blower tap and energizes the
COOL_HI blower tap after the 1 second delay.
When the thermostat removes the call for 2nd stage
cooling (Y2), the control de-energizes the COOL_HI
blower tap and energizes the COOL_LO blower tap.
When the thermostat removes the call for cooling (Y),
the control de-energizes the COOL_LO blower tap
after a cooling off delay period of 30 seconds.
If a call for emergency heat (W) exists with a call for
2nd stage cooling, the call for heat shall proceed as
normal except the blower remains energized on the
COOL_HI speed. If the call for cool goes away while a
call for emergency heat exists, the 2nd stage cooling
off delay is canceled and the blower operation reverts
to the heat cycle.
HEATING MODE:
Heating Operation: Air-Conditioning (A/C) Mode -
Configured for Flow Sensor (FS) Input:
Circulating Pump Operation:
On a call for heating, terminal “W” of the thermostat is
energized. The control monitors the FS input and
energizes the circulating pump if the FS signal is
present.