User's Manual

53
D. If you have a heat pump without aux heat, the First Alert model
THERM-500 will require 5 wires: R (24Vac), C (24Vac), W1/O/B
(Reversing Value), Y (1
st
Stage Compressor), and G (Fan).
If you are short 1 wire, there are at least 3 options available to connect
the First Alert model THERM-500:
1. Use the available wires as instructed in the“Making 4 Wires
Work When 5 Wires Are Required” section on page 50 and note
that the fan will only operate with a Heating or Cooling demand.
2. Pull new thermostat wire from the HVAC equipment to the
thermostat so that there are at least 5 wires available.
3. Purchase and install an Add-A-Wire accessory.
E. If you have a heat pump with aux heat, the First Alert model
THERM-500 will require 6 wires: R (24Vac), C (24Vac), W1/O/B
(Reversing Value), Y (1
st
Stage Compressor), W2 (Aux Heat), and G
(Fan).
If you are short 1 wire, there are at least 3 options available to connect
the First Alert model THERM-500:
1. Use the available wires as instructed in the“Making 5 Wires
Work When 6 Wires Are Required” section on page 51 and note
that the fan will only operate with a Heating or Cooling demand.
2. Pull new thermostat wire from the HVAC equipment to the
thermostat so that there are at least 6 wires available.
3. Purchase and install an Add-A-Wire accessory.
Installation Instructions