iO-DFK Installation Sheet

Outdoor temperature outdoor thermostat setpoint (High Balance Point)above
2 Heat / 1 Cool
When the space thermostat calls for heating and the outside temperature is above the setpoint (High Balance Point) of
the outdoor thermostat (iO-DFK-ODT), the heat pump will operate as first stage heat. If there is a call for second stage
heat, or if the thermostat is placed in the emergency heat mode, the iO-DFK will automatically de-energize ‘Y1’ and
energize ‘W1’. The furnace will then be brought on and will remain on until the thermostat call is satisfied.
3 Heat / 2 Cool
When the space thermostat calls for heating and the outside temperature is above the setpoint (High Balance Point) of
the outdoor thermostat (iO-DFK-ODT), the heat pump will operate as first stage heat. If there is a call for second stage
heat, the second stage compressor will be energized. If there is a call for auxiliary heat, or if the thermostat is placed in
the emergency heat mode, the io-DFK will automatically de-energize ‘Y1’ and ‘Y2’ to the heat pump outdoor unit and
energize ‘W1’. The furnace will then be brought on and will remain on until the thermostat call is satisfied.
Outdoor temperature outdoor thermostat setpoint (Low Balance Point)below
When the space thermostat calls for heating and the outside temperature falls below the setpoint (Low Balance Point)
of the outdoor thermostat, the heat pump will be locked out and the furnace will become first stage heat. The furnace
will remain energized until the thermostat call is satisfied.
Cooling Mode
When the space thermostat calls for cooling, the outdoor balance point is bypassed regardless of the outdoor
temperature and only the heat pump will be energized.
Reversing Valve
It is important that the reversing valve selector switch located on the iO-DFK be set in the proper position. For heat
pumps that energize the reversing valve in the cooling mode, set the selector switch to ‘O’. For heat pumps that
energize the reversing valve in the heating mode, set the selector switch to ‘B’. Heat pump thermostats should also be
configured in the same manner.
Blower control
The iO-DFK will stop the blower anytime it switches between heat pump and furnace operation and the blower will
restart at the proper speed.
iO-DFK-DAT Discharge Air Thermostat
An optional iO-DFK-DAT discharge air thermostat can be connected to the ‘D’ and ‘D’ terminals on the iO-DFK board to
limit the discharge air temperature during defrost cycle. (Typically used with an oil furnace) The sensor setpoint should
be set at 90° F.
iO-DFK-ODT Outdoor Thermostat Specifications
The iO-DFK-ODT Outdoor Thermostat is a SPDT bi-metal outdoor rated thermostat. Temperature range is 0° F - 100° F
with a 2° F heating and 3° F cooling differential. The device is UL Listed and CSA Certified.
WIRING DIAGRAM ON FRONT
iO-DFK
Dual Fuel Kit Sequence of Operation
iO-06-1215-071917
HVAC Controls
Indianapolis, IN 46237
www.iohvaccontrols.com
For Technical Support Call Toll Free: 866-225-5032