Rinnai 37AHB SERIES - Manual (Page 25)

Rinnai Corporation Hydronic Furnace (37AHB) Manual 25
Sequence of Operation
If the FS signal is NOT present, the control will
energize the circulating pump for 60 seconds in an
attempt to activate the Flow Sensor (FS). If the FS
signal does not become active during the time, the
control will de-energize the circulating pump for 60
seconds and then start another 60 seconds with the
circulating pump energized to try to activate the Flow
Sensor. Sequential attempts to activate the Flow
Sensor will use 60 second, 120 second and 180
second de-energized periods for the circulating pump.
The de-energized period will circle back to the original
60 second off period following sequential unsuccessful
energized attempt to activate the Flow Sensor. During
this time the Status LED will rapidly flash, indicating
that a heat demand is present, but not being satisfied
because of the state of the FS input signal.
Heat Blower ON Delay:
The control waits for 25 seconds after the circulator
pump is energized (and FS signal is present) and then
energizes the indoor blower heat speed and the
humidifier output.
If the thermostat demand for heat is removed, the
control de-energizes the circulating pump, and runs
the heat speed blower and humidifier through the
selected blower off delay as defined by the dip switch
settings in Figure 15.
Steady Heat:
Control inputs are continuously monitored to ensure
the call for heat remains.
If the thermostat demand for heat is removed, control
operation proceeds to the operation described in “Heat
Blower ON delay”
section above.
If the FS input becomes absent during steady state
heating, the sequence in “Circulating Pump Operation”
section above will become active and the blower off
delay will run.
If the FS input signal returns within the same heating
demand period (W), the control will begin jogging the
circulator pump as described in “Circulating pump
Operation”
section, normal heating operation will
resume.
Heat Blower OFF Delay:
When the heating thermostat demand (W) is removed,
the control de-energizes the circulating pump and then
de-energizes the indoor blower motor and humidifier
after a delay time as defined by the dip switch settings
in Figure 15.
Blower timing begins when the thermostat is satisfied.
The control returns to standby when the blower off
time is complete.
If the thermostat call for heat returns before the blower
off delay is complete, the control re-energizes the
circulating pump and resumes a normal heating
sequence.
Heating Operation: Heat-Pump (HP) Mode -
Configured for Flow Sensor (FS) Input:
Single-Stage HP Demand - Call for Heat:
The thermostat calls for heat by connecting (Y and R).
The control will proceed to the Heat Blower ON Delay
when a single stage heat demand exists.
The Heat Pump is the primary source of heating in this
mode.
Blower ON Delays:
The control waits for 1 second and then energizes the
COOL_HI tap if and the humidifier output. If the
thermostat demand for heat is removed, the control
runs the COOL_HI tap and humidifier through a fixed
30 second blower off delay.
Steady Heat:
Control inputs are continuously monitored to ensure
the call for heat remains.
If the thermostat demand for heat is removed, control
operation proceeds to the operation described in the
“Blower On and Off Delays”
section.
The Heat Pump is the primary source of heating in this
mode.
Second Stage HP Demand – Call for Heat:
After the control enters into a Steady Heat mode, the
second stage heating demand (Y2) input is monitored.
If a (Y2) demand is sensed, the COOL_HI blower
speed will be energized. If the (Y2) demand becomes
absent, the COOL_HI blower speed will immediately
be de-energized and the COOL_LO blower speed will
again be energized.
Heat-Pump Emergency Heat Demand:
The Emergency Heat (W) input is continually
monitored, and is a higher priority than single or 2-
stage heating demands. If the Flow Sensor (FS) input
signal is present with a call for emergency heat (W),
the circulator pump will immediately be energized.