Replacing Existing Thermostat - Aprilaire 8353 User Manual

Features
• Four setpoints for weekday programming—two setpoints for
weekend comfort.
• Two "AA" ENERGIZER brand batteries retain program memory,
even during power outages.
• Low battery indicator.
• Fahrenheit/Celsius display option.
• Programmable from 45°F (4°C) to 90°F (32°C).
• Accuracy within ± 1 degree.
• Adjustable temperature differential: 1-3 degrees.
• Maintains summer and winter programming.
• 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
M, 4, RH, R5 or R
V or RC
Y or Y6
H, W or 4
F or G
C*
*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.
New Label
RH
RC
Y
W
G
Y or None
2
Description
Heat Transformer,
hot side
Cooling Transformer, hot
side
Cooling control
Heating control
Fan control relay
Either cooling control or
common side of trans-
former