Power Outages; Mounting The Thermostat; Setting Day And Time - Honeywell T8621A User Manual

When the batteries are low, the display will flash
REPL BAT. The building owner will have 20-30 seconds to
install new batteries after removing old batteries from
thermostat. After 20-30 seconds, it will be necessary to
reprogram. REPL BAT indication will disappear when ther-
mostat is mounted back on the subbase.
If batteries are completely dead, the display will go
blank. After replacing the battery in this case, reprogram-
ming will be necessary.

POWER OUTAGES

Backup batteries will hold the programming and keep

SETTING DAY AND TIME

Restore 24 V power to the thermostat. When power is
applied to the thermostat, the display will read 1:00 PM and
room temperature. It will go off for a few seconds, then begin
to flash on and off. Set present day and time.
SET
PRESENT
Press .
DAY/TIME
Press to set the current day. Each press of the
DAY
DAY key advances the display one day.
Press TIME
AHEAD
HEATING
NOTE: When heating setting is changed, thermostat will
wait up to 5 minutes before turning on the heating
equipment. This delay protects the compressor.
Move the system switch to HEAT and the fan switch to
AUTO. Press WARMER key until the setting is about 10 F
[6 C] above room temperature. Heating should start (both
stages if multistage), and the fan should run (may be a short
C.
RUN
PROGRAM
SET
PRESENT
DAY
DAY/TIME
HOLD
SET
TEMP HEAT/COOL
Fig. 12—Mounting thermostat on subbase.
BACK
or to set the current time.
the display on during most power outages. Once the power
is restored, the system will resume normal operation.
If the display goes off when power is lost, either the
backup batteries need to be replaced or are not installed.
When power is restored, the display will flash 1:00 PM to
remind you to reprogram.

MOUNTING THE THERMOSTAT

Hang the thermostat on the tabs at the top of the base
(Fig. 12a). Swing down and press on lower edge until
thermostat snaps in place (Fig. 12b). Open cover, and
tighten the captive mounting screws (Fig. 12c).
A.
SYSTEM
TEMPERATURE
PRESENT
SETTING
TIME
SKIP
COPY
NEXT
PERIOD FROM AHEAD WARMER
PERIOD
CANCEL COPY BACK CHANGE
COOLER
PERIOD TO TO LAST
PERIOD
If the display will not come on—
— check mounting of thermostat to subbase. If loose or
misaligned, remove thermostat and reinstall on the
subbase, making sure it is firmly attached.
— check to see that heat or cool system power is on.
— check voltage between R and C; should be 24 to 30
Vac.
CHECKOUT
delay on gas or oil forced air systems). Press COOLER key
until the setting is about 10 F [6 C] below room tempera-
ture. The heating equipment should shut off, followed by the
fan.
NOTE: On an AUTO changeover thermostat, the cooling
temperature must be set at least 3 F [2 C] above the
heating temperature, or display will flash.
6
B.
SYSTEM
AM
MON ROOM
MORNIMG
HEAT ON
M843