Honeywell HEAT PUMP THERMOSTAT T8411R, Manual, Page: 8 / 12

T8411R ELECTRONIC HEAT PUMP THERMOSTAT
68-0185—2 8
Sequence of Operations
The Fan, Heat and Cool outputs are relay controlled. A loss of
ac power, or a change in the SYSTEM switch setting can
cause the outputs to turn off. Table 1 shows the sequence of
operations for the Fan settings and System modes.
Fan Control
The FAN switch settings are On and Auto.
On:The fan runs continuously.
Auto:The fan starts and stops with the equipment.
Heat Mode
With the SYSTEM switch in the Heat position, the thermostat
controls the heating system. On a call for heat, the W and G
terminals are energized and a flame is shown on the digital
display. The B terminal is powered continuously while system
switch is in Heat.
Cool Mode
With the SYSTEM switch in the Cool position, the thermostat
controls the cooling system. On a call for cool, the G and Y
terminals are energized and a snowflake is shown on the
digital display. The O terminal is powered continuously while
system switch is in Cool.
Em. Ht. Mode
With the system switch at Em. Ht., the thermostat controls
Em. Ht. On a call for emergency heat, the E, G and L
terminals are energized and an indicator is displayed on the
LDD. The L terminal is powered continuously while system
switch is in Em. Ht. In severe weather, the W2 terminal can
also energize.
Minimum Off-Timing
A minimum off-timer in the T8411R assures that the compressor does
not come on again for at least five minutes after it turns off. The
minimum-off timer is triggered when the compressor turns off. If the
compressor turns off when the setpoint is changed, then the
minimum-off timer is triggered. Power interruption and power
restoration also trigger the minimum off-timer which operates
on the first stage of heating and cooling.
Table 1. Sequence of Operations.
a
The O terminal is powered continuously in cooling, the B terminal is powered continuously in heating and the L terminal is
powered continuously in emergency heat as a function of the system switch position even without a call for heat or cool.
CHECKOUT
Heating
1. Slide the SYSTEM switch to Heat and the FAN switch to
Auto.
2. Press and hold the s key to raise the temperature set-
ting several degrees above the room temperature. After
approximately five minutes the W1 and G terminals are
energized and the heating equipment starts.
3. Press the
▼
key to lower the temperature setting below
the room temperature. Heating equipment should stop.
Cooling
CAUTION
Compressor Damage Hazard
Operating at too low of an outdoor temperature
can cause compressor damage.
Do not operate cooling if outdoor temperature is below
50°F (10°C). Refer to manufacturer recommendations.
Allow the compressor to remain off for five minutes
before restarting.
1. Slide the SYSTEM switch to Cool and the FAN switch to
Auto.
2. Press the
▼
key to lower the temperature setting sev-
eral degrees below the room temperature. After approx-
imately five minutes the G and Y terminals are
energized and the cooling equipment starts.
3. Press the
▲
key to raise the temperature setting above
the room temperature. Cooling system should shut
down.
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 system turns the fan
on or off with the equipment.
Make certain all equipment responds properly to the
thermostat.
FAN Switch Settings SYSTEM Switch Settings Call for Action Energize Terminals Display Icons
Auto Cool None O None
Cooling O, Y, G
✼
Heat None B None
Stage 1 heat B, W1, G
Stage 2 heat B, W1, W2, G , Aux Ht indicator
Em Ht None L Em Ht indicator
Stage 1 heat L, E, G
, Em Ht indicator
Stage 2 heat L, E, W2, G , Em Ht and Aux Ht indicators