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Features
• Single Stage heat pump compatible.
• Zone system compatible as a master thermostat.
• Low battery indicator.
• Fahrenheit/Celsius display option.
• Adjustable from 45(F (4°C) to 90°F (32(C).
• Accuracy within ± 1 degree.
• Adjustable temperature differential: .5 – 1.5 degree.
• Low temperature freeze protection. While in heat mode, thermostat
will mechanically turn on heat if temperature drops to 40°F (4°C) –
even if batteries are missing or drained.
• Automatic heating shutdown if temperature exceeds 90°F (32°C).
Replacing Existing Thermostat
1. Turn off power to heating and cooling system.
2. Remove cover of old thermostat to expose wires.
Do not disconnect wires. (Fig. 1)
3. Label wires per Table 1.
Table 1
Old Label New Label Description
M, 4, RH, R5 or R RH Heat Transformer,
hot side
V or RC RC Cooling Transformer,
hot side
Y or Y6 Y Cooling control
H, W or 4 W Heating control
F or G G Fan control relay
C* Y or None Either cooling control
or common side
of transformer
O O Cool Active Reversing
Valve
B B Heat Active Reversing
Valve
*NOTE: On some older models, the C terminal can be either the cooling
control or the common side of the transformer. Check furnace wiring
diagram to verify C terminal. If it is the common side of the transformer,
cap the wire and tuck into the wall.
If it is the cooling control, connect
to the Y terminal.
4. After labeling wires, remove wires from terminals.
5. Remove existing thermostat base from wall.
6. Refer to the following section for instructions on how to
install thermostat.
Installing Model 8334 Thermostat
NOTE: For new installations, mount thermostat on inside wall, 4-5 feet
above the floor. Do not install behind a door, in a corner, near air vents,
in direct sunlight, or near any heat or steam generating fixtures.
Installation at these places will affect thermostat operation.
1. Turn power off to the heating
and cooling systems.
2. Place COOL-OFF-HEAT
In OFF position.
3. Place FAN: AUTO-ON switch
Into AUTO position.
4. Remove the cover using a coin
or screwdriver.
5. Place thermostat against the wall at desired location. Make sure
wires will feed through opening on base of thermostat.
6. Mark placement of mounting holes. See Fig. 3.
Set base aside.
7. Drill the marked holes using a 3/16" drill bit. NOTE: Enclosed plastic
anchors do not require drilled hole for drywall.
8. Tap plastic anchors into the wall.
9. Align base with plastic anchors and feed wires
through opening.
10. Secure base to wall with supplied screws.
11. Connect wires to terminal strip. Refer to wiring diagrams on other
side of this sheet. Make sure wire connections are secure.
12. Place fan option switch into either the "ELEC" or "GAS" position
depending upon the type of furnace. Refer to Figure 4.
figure 4
13. Put the °F/°C switch to either °F for Fahrenheit display
or °C for Celsius display readout.
14. Put the HP/NON HP switch to either the HP for Heat Pump or NON
HP for furnace applications in the proper position.
15. Install two “AA” ENERGIZER brand batteries or equivalent into bat-
tery compartment. Be sure to match positive (+) ends of batteries
with positive (+) battery terminals in the battery compartment.
16. Replace cover onto thermostat by snapping into place.
17. Turn on power to system. Test thermostat as described in
the following section.
IMPORTANT SAFETY INFORMATION
WARNING:
• Always turn off power at the main power source by unscrewing
fuse or switching circuit breaker to the off position before installing,
removing, cleaning, or servicing thermostat.
• Read all of the information in this manual before installing or
programming this thermostat.
• This is a 24V AC low-voltage thermostat. Do not install on voltages
higher than 30V AC.
• All wiring must conform to local and national building and electrical
codes and ordinances.
• Do not short (jumper) across terminals on the gas valve or at the
system control to test installation. This will damage the thermostat
and void the warranty.
1 2 3 4 5
COOL OFF HEAT FAN: AUTO - ON
>
>
COOL OFF HEAT
FAN: AUTO - ON
Figure 1
Figure 2
MOUNTING HOLES
ELECTRIC/
GAS SWITCH
F°/°C
Switch
HP/NON HP
Switch
1 Heat / 1 Cool Digital
Electric / Gas
MODEL 8334
User’s Manual
Installation and
Operation
ELECTRONIC THERMOSTATS
®
°F/°C
SWITCH