All Fuel Kit Install Instructions

2
An optional outdoor thermostat, OT18-60A, can be in-
stalled in the heat pump unit and used with the AFE18.
When used, the tab on the AFE18 control board next to the
terminal strip for the heat pump field wiring connections
must be broken for the outdoor thermostat to function with
the control. The thermostat can be field adjusted to a break-
even temperature set point appropriate for the installation.
Refer to the installation instructions provided with the
OT18-60A for the appropriate mounting location for the
heat pump unit.
OPERATION
1.0 COOLING
On heat pump units, when the room thermostat is set to the
cooling mode, 24Vac is constantly supplied to terminal “O”
of the AFE18 at the thermostat input and to the reversing
valve. The constant 24Vac at the “O” terminal of the AFE18
is a signal that the unit is in the cooling mode and its software
won’t allow the furnace to be turned on.
1.1. On a demand for cooling on a single stage heat pump,
the room thermostat energizes “Y” and “G”. This sup-
plies 24Vac to terminals “G” and “Y” of the AFE18. If
the 3 minute anti-short delay has expired, the “Y” out-
put to the heat pump unit will be energized and the
compressor and condenser fan will start. On ASZ two
stage heat pumps, the room thermostat energizes “Y1”
and “G”. This supplies 24Vac to terminals “G” and “Y1”
of the AFE18. If the 3 minute anti-short delay has ex-
pired, the “Y” output to the heat pump unit will be ener-
gized and the compressor will operate on low stage
and condenser fan and indoor fan will operate on low
speed.
1.2 When an “Y2” demand is initiated on ASZ two stage
heat pumps, 24Vac is supplied to terminal “Y2” of the
AFE18 and terminal “Y2” of the heat pump. The con-
trol board in the ASZ unit changes the compressor to
high stage and condenser fan and indoor fan to high
speed operation. When the “Y2” demand is satisfied,
the control board in the ASZ unit will return the com-
pressor to low stage and condenser fan and indoor
fan back to low speed operation. On some digital/
electronic thermostats, “Y2” will remain energized
until the first stage demand “Y” is satisfied.
1.3 When the “Y” cooling demand is satisfied, the room
thermostat removes the 24Vac from terminals “Y” and
“G” and the unit turns off. The 3 minute anti-short cycle
delay is initiated for the compressor.
2.0 HEATING
On heat pump units, when the room thermostat is set to
the heating mode, the reversing valve is not energized.
This is a signal to the
AFE18 that the unit is in the heating
mode. As long as the thermostat is set for heating, the
reversing valve will be in the de-energized position for
heating except during a defrost cycle.
2.1 On a demand for heat on a single stage heat pump,
the room thermostat energizes “Y” and “G”. This sup-
plies 24Vac to terminal “Y” of the AFE18, to the “Y”
terminal of the defrost board in the heat pump and the
to the “G” terminal of the furnace. The heat pump and
indoor fan will start in the heat mode. On a demand for
heat on an ASZ two stage heat pump the room ther-
mostat energizes “Y1” and “G”. This supplies 24Vac
to terminal “Y1” of the AFE18, to the “Y” terminal of
the defrost board in the heat pump and to the “G” ter-
minal of the furnace. The compressor will start in low
stage and the condenser fan and indoor fan will start
on low speed in the heat mode. As long as 24Vac is
present at terminal “Y” of the defrost board during the
heating mode, the defrost board accumulates com-
pressor run time.
2.2 When an “Y2” demand is initiated on ASZ two stage
heat pumps, 24Vac is supplied to terminal “Y2” of the
AFE18 and terminal “Y2” of the heat pump. The con-
trol board in the ASZ unit changes the compressor to
high stage and condenser fan and indoor fan to high
speed operation. When the “Y2” demand is satisfied,
the control board in the ASZ unit will return the com-
pressor to low stage and condenser fan and indoor
fan back to low speed operation. On some digital/
electronic thermostats, “Y2” will remain energized
until the first stage demand “Y” is satisfied.
2.2B If outdoor thermostat, OT18-60A, is used and the tem-
perature is below the set point, i.e. break even point,
the outdoor thermostat will switch the “Y” heating de-
mand to the “W1” input to the furnace. The AFE18 will
remove the “Y” and “Y2” demands from the heat pump
if present and remove the “G” demand from the fur-
nace. With the “Y” input to the heat pump removed,
the compressor will be turned off and the defrost board
will store the compressor’s accumulated run time in
memory. The furnace will be turned on and remain on
until the “Y” demand for heating is satisfied. The in-
door blower will operate at the speed designed for fur-
nace only operation. The unit will operate this way on
a demand for heating as long as the outdoor thermo-
stat remains in this position.