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T834B; T834C; T834J HEATING-COOLING THERMOSTATS
RECALIBRATION
These thermostats are calibrated at the factory and should
not need recalibration. If the thermostat seems out of
adjustment, first check for accurate leveling. To check
calibration, proceed as follows:
1. Move the temperature setting lever to the left
(low) end of the temperature scale. Place system
switch at OFF. Wait at least five minutes.
2. Remove the thermostat cover. Move the setting
lever until the switch just makes contact. The
mercury in the switch will roll to the left end of
the tube.
3. Replace cover and wait five minutes for the cover
and the thermostat to lose the heat it has gained
from your hands. If the thermometer pointer and
the setting lever indicator read approximately the
same, no recalibration is needed.
If recalibration appears necessary, proceed as follows:
1. Place the temperature setting lever at the same
setting as the thermometer. Remove cover.
2. Insert Honeywell part no. 104994A Calibration
Wrench (order separately) onto the hex nut under
the coil. See Fig. 13. Holding the setting lever so
it does not move, turn the wrench clockwise
until the mercury rolls to the right end of the tube.
Remove wrench and replace cover.
To ensure accurate temperature control, do not
touch or breathe on bimetal or thermometer.
Automation and Control Solutions
Honeywell International Inc.
1985 Douglas Drive North
Golden Valley, MN 55422
69-0444—10
69-0444—10 G.H. Rev. 5-99
Honeywell Limited—Honeywell Limitée
35 Dynamic Drive
Scarborough, Ontario M1V 4Z9
3. Move the setting lever to a low setting. Wait at
least five minutes for temperature to stabilize.
4. Slowly move the setting lever until it reads the
same as the thermometer.
5. Remove cover. Holding the setting lever so it
does not move, reinsert wrench and carefully turn
counterclockwise
the left end of the tube but no farther.
6. Recheck calibration. Set thermostat system
switch for desired operation and replace cover.
Fig. 13. Recalibration procedure.
8
until the mercury rolls to
COIL SHOWN WITHOUT
HEAT ANTICIPATOR
CALIBRATION
WRENCH
M2044A
www.honeywell.com/yourhome
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