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Installation with A hot Air System
Electrical interconnection of the HF60 to an existing heat pump, or fuel-fired hot air furnace:
Interconnection with a heat pump will generally require a second thermostat to be installed. It is recommended that a new
electronic thermostat be installed as close to the existing thermostat as possible. Installing within one foot of the existing
thermostat is recommended for ease of interconnection and similar temperature sensing ability.
If programmability is desired, both thermostats should have this capability. If only the new thermostat is programmable, you’ll
need to keep the existing thermostat set several degrees below the lowest programmed temperature setting of the new
thermostat. NOTE: In this configuration, if the HF60 cannot maintain the desired thermostat setting, the room will be allowed
to cool to the lower set point of the existing thermostat before allowing the heat pump to operate.
Special note: Even if the heat pump has a multi-stage thermostat, it cannot be re-wired to make the first stage control the
HF60, and the second stage control the heat pump. All multi-stage heat pump thermostats are interconnected so that the
compressor unit and/or the changeover solenoid activate with the first stage only.
Controlling the existing furnace fan during overheat situation.
Following the wiring diagram on the next page, you will need to supply and install a piece of 18/3 Thermostat wire between
the low-voltage control terminal strip on the upper left-hand side of the HF60’s control cover, to the low-voltage control of
the existing furnace.
Note: Some systems may have external terminals and some may have them enclosed within the unit. If the connections
to the existing system need to be made internally, be sure to use the proper protective grommet or connector where
passing through the cabinet of the existing unit.
If the wiring used does not match the colorings listed, follow the corresponding numbers on the terminal strips to ensure
proper connection.
Step 1. Disconnect electrical power to the existing heating system.
Step 2. Install the above mentioned thermostat wire between the two systems
Step 3. Connect the three (3) wires to the HF60 control terminal strip as indicated.
Step 4. Remove the green wire which comes from the existing thermostat and connects to the terminal marked “G” on the
existing system and splice it to the green (or #1) wire from the HF60.
Step 5. Connect the white wire (or #5) from the HF60 to the “G” terminal of the existing system. This white wire should be
the only wire connected to “G”.
Step 6. Now, the red (#3) wire from the HF60 should be added to the “R” terminal of the existing system. Do not remove or
replace any existing wires from “R”, just add this one to them.
Restore power to the existing system only. Using the existing thermostat, increase the setting to verify that the system works
as it did prior to the interconnection. Increase and decrease the thermostat a few times to verify proper reaction. In the case
of a heat pump system, be sure the outdoor compressor unit is also cycling. Notice: Most compressors have a built in lockout
timer (usually 5 minutes) so you may need to wait between thermostat adjustments to verify proper operation.
Once you are certain that nothing changed with the operation of the existing system, turn the existing system’s thermostat
down far enough that it won’t come on during the test. Connect power to the HF60, and turn on the circuit breaker on the
front of the unit. With the control in the “OFF” position, turn the feed adjuster knob to “Test”. When the OVERHEAT SAFETY
ZONE light illuminates, the fan on the existing system should come on. Be sure that the fan is the only thing on. There should
be no power to the compressor or the oil or gas burner.
