Aprilaire 8355 user manual Features, Replacing Existing Thermostat

Features

•Four pre-programmed setpoints for each day of the week.

•Fast and easy programming for setting all days of the week simultaneously.

•Energy efficient recovery.

•Residual cooling for added air-conditioning efficiency.

•Two “AA” ENERGIZER brand batteries retain program memory, even during power outages.

•Low battery indicator.

•Multi-colored LED indicators for system status.

•Zone compatible as master thermostat.

•Fahrenheit/Celsius display option.

•Programmable from 45°F (7°C) to 90°F (32°C).

•Accuracy within ±1 degree.

•Adjustable temperature differential: 1-3 degrees.

•Maintains summer and winter programming.

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
R, V-VR or VR-R	R	24 VAC
Y, Y1 or M	Y1	Stage 1 Cooling/Heating Circuit
O or R	O	Reversing Valve (Cooling Mode)
B	B	Reversing Valve (Heating Mode)
G or F	G	Fan Contactor Circuit
Y2	Y2	2nd Stage Cooling Circuit
W1 or W2 or W-U	W2	2nd Stage Heating Circuit
L or X	L	System Monitor LED
E	E	Emergency Heating Circuit
C, X or B	C	24 VAC, Transformer Common Side

NOTE: This thermostat requires a 24V AC common wire for proper operation.

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.

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