1 69-0642—1
D.F. • Rev. 12-94 • • ©Honeywell Inc. 1994 • Form Number 69-0642—1
T8190A/191108AJ Heating or CoolingThermostat/Wallplate; T8190A/Q682BHeating/Cooling Thermostat/Subbase
Installation Instructions for the Trained Service Technician.
TABLE 1—SYSTEM COMPATIBILITY FOR NON-BATTERY POWERED THERMOSTATS.
aIf thermostat is not compatible with the system being controlled, the system will not operate. No hazard exists. The
thermostat will not be damaged unless it is used to directly control a line voltage system. For proper system operation, a
Honeywell R841 or R8239D1015 Isolating Relay must be added to the thermostat control circuit.
bConsult manufacturer for installation requirements.

Preparation

Check thermostat and subbase (if used) suitability for the
heating, cooling, or heating/cooling system. Refer to Table 1.
Assemble tools required: flat-bladed screwdriver, hand
or power drill with 3/16-in. drill bit, wire cutter/stripper or
sharp knife, bubble level or plumb bob and line.
Assure power is off to the heating, cooling, or heating/
cooling system at the main fuse panel. Most buildings have
a separate switch box or circuit breaker for disconnecting
power to the heating and cooling (if applicable) equipment.
This thermostat is compatible with all heating, cooling or
heating/cooling systems when thermostat is powered by
batteries. If thermostat is not powered by batteries, refer to
Table 1 for thermostat and system compatibility information.
Type of Heating System to be Controlled Conditions/Compatibility
Electric (Line Voltage)—typical baseboard
and radiant • The R8239D1015 Isolating Relay or R841 Silent Switching Center
must be installed in the thermostat control circuit.a
Fan Coil Unit • Compatible. Assure correct subbase identity is selected for fan
control.
Gas—Direct Spark Ignition (DSI),
Intermittent Pilot (IP), and Standing
Pilot (SP)
• Compatible. If not using battery backup, assure that 24V control
transformer common is accessible for connection to thermostat
cable conductor and power to the transformer is not regularly
interrupted by high temperature or limit operation.
Heat Pump • Compatible. Assure correct subbase identity is selected for
fan control and changeover control (O terminal for cool and
B terminal for heat).
Hot Water Zone • Honeywell 2-wire valves are compatible.
• Some non-Honeywell 2-wire valves require an R8239D1015
Isolating Relay in the thermostat control circuit.a
• Some 3-wire valves require an R8239A1052 Isolating Relay in the
thermostat control circuit.a, b
Oil • If not using battery backup, assure that the 24V control transformer
common is accessible for connection to thermostat cable conductor
and power to the transformer is not regularly interrupted by high
temperature, purge cycle, or limit operation.
Vent Damper • Honeywell damper motors are compatible.
• Some non-Honeywell damper motors require an R8239D1015
Isolating Relay in the thermostat control circuit.a Check control
amperage requirement.
Warm Air Zone • Most are compatible.
NOTE: Order Q682B Subbase separately.

Recycling Notice

This control contains mercury in a sealed tube. Do not
place control in the trash at the end of its useful life.
If this control is replacing a control that contains mercury
in a sealed tube, do not place your old control in the trash.
Contact your local waste management authority for in-
structions regarding recycling and the proper disposal of this
control, or of an old control containing mercury in a sealed
tube.
If you have questions, call Honeywell Inc. at 1-800-
468-1502.
M3375
M3375