Honeywell T8775A specifications Checkout

T8775A,C THE DIGITAL ROUND™ NON-PROGRAMMABLE THERMOSTATS

ROOM

SET

M19490

Fig. 18. Room temperature display.

Adjust Temperature Setpoint

Turn the dial clockwise to raise the temperature setpoint. Turn the dial counterclockwise to lower the temperature setpoint (see Fig. 16).

Power Stealing

The T8775 thermostat steals power from R and W or Rc and Y depending on the system switch position. See Table 3.

Table 3. T8775 Power Stealing.

Power Stealing Circuit

System Switch	T8775A	T8775C
Heat	R and W	R and W
Off	—	R and W
Cool	—	Rc and Y

The T8775 Thermostat only operates when mounted on the wallplate with 24 Vac applied. Batteries are not required for operation because the temperature setpoint is permanently retained in memory.

Sequence of Operations

See Table 4 for Sequence of Operations.

Table 4. Sequence of Operations.

Fan Switch Settings	System Switch Settings	Call for Action	Energize Terminals	Display Icons
Auto	Off	None	None	None
Auto	Heat	Heating	Wa	Flame
Auto	Cool	Cooling	Y,G	Snowflake
On	Off	Fan	G	None
On	Heat	Heating	W,G	Flame
On	Cool	Cooling	Y,G	Snowflake

aIf fuel switch is set to E, both W and G are energized in a call for heat.

CHECKOUT

Cooling (T8775C only)

CAUTION

Low Temperature Hazard.

Operating at too low of an outdoor temperature may cause compressor damage.

Do not operate cooling if outdoor temperature is below 50°F (10°C). Refer to manufacturer’s recommendations.

Minimum Off-Timer

The minimum off-timer in the T8775C Thermostat assures that the cooling compressor does not turn on for at least five minutes after it turns off. The snowflake will flash in the display if there is a call for cooling during the 5-minute off-time.

The following activates the 5-minute minimum-off timer:

•Initial startup

•Power interruption

•Compressor turns off:

—Setpoint is raised above the room temperature

—System switch is changed from the cool mode

—Thermostat ends the call for cooling

NOTE: The 5-minute minimum-off timer does not apply to heating.

1.Slide the system switch to COOL and the fan switch to AUTO.

2.Lower the temperature setpoint several degrees below the room temperature.

3.A snowflake will appear in the display and the cool- ing should turn on.

4.Raise the temperature setpoint several degrees above the room temperature.

5.The snowflake will disappear from the display and the cooling should turn off.

Heating

1.Slide the system switch to HEAT and the fan switch to AUTO (T8775C only).

2.Raise the temperature setpoint several degrees above

the room temperature.

3. A flame will appear in the display and the heat should turn on.

4.Lower the temperature setpoint below the room temper- ature.

5. The flame will disappear from the display and the heat should turn off.

Fan

1.Slide the system switch to OFF and the fan switch to ON. The fan should run continuously.

2.Slide the fan switch to AUTO. The fan should turn off.

NOTE: Make sure that all equipment responds properly to the thermostat.

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