Power & Reset Options; Wiring Terminal - Aprilaire 8620 Installation Instructions Manual

INSTAllATION
pOWER & RESET OpTIONS
The thermostat is dual power . It can either be AC or
battery powered, or both (to provide backup power for
the clock). Batteries are optional if your thermostat was
wired to run on AC power when installed .
For heat pump systems the C terminal must be connected
to the common of the 24VAC transformer in order for the
system fault and emergency heat indicators to operate .
The thermostat has a memory backup that saves the
thermostat settings in case of a power interruption . The
system settings will be retained but the clock will reset
after 90 seconds with no battery or AC power .
The reset button located under the battery cover can
be used to reset the thermostat to factory defaults . The
system settings will also be reset to default .
Note: The reset button is disabled when the thermostat
is removed from the wall for programming .

WIRINg TERMINAl

I2 C I1 O/B Y Y2 G RC R W2 W L S2 S1
Wire specifications:
18-24 gauge thermostat wire
Installation notes:
• Ensure power at the HVAC equipment is off.
• Loosen screw terminals, insert stripped wire and
re-tighten .
• Push the excess wire back into the opening and plug
the wall opening to prevent drafts .
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I1 & I2 – Indoor Air Quality control output
C – Common (optional when powered by batteries)
O/b – Reversing valve
T1 T2
Y – 1st stage cooling / compressor
Y2 – 2nd stage cooling / compressor
g – Fan
RC – 24VAC supply cooling
1
R – 24VAC supply heating
1
W2 – 2nd stage heat / auxiliary
W – 1st stage heat / auxiliary
l – System fault indicator (optional) (heat pump only)
S1 & S2 – outdoor temperature sensor (included)
T1 & T2 – remote temperature sensor (optional)
1 Jumper between RC & R is used in single transformer systems
(see wiring diagrams).
INSTAllATION
CONVENTIONAl HEAT/COOl WIRINg DIAgRAMS
SINglE TRANSfORMER (USE JUMpER WIRE)
RESET
BUTTON
I2 C I1 O/B Y Y2 G
HEAT pUMp WIRINg DIAgRAMS
SINglE TRANSfORMER (USE JUMpER WIRE)
I2 C I1 O/B Y Y2 G
TWO TRANSfORMERS (REMOVE JUMpER WIRE)
RC R W2 W L S2 S1 T1 T2 I2 C I1 O/B
TWO TRANSfORMERS (REMOVE JUMpER WIRE)
I2 C I1 O/B
RC R W2 W L S2 S1 T1 T2
Y Y2 G RC R W2 W L S2 S1 T1 T2
Y Y2 G RC R W2 W L S2 S1 T1 T2
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