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Q539A, H and J Subbases
Installation Instruction for the Trained Service Technician.
Application
Q539 Subbases provide cooling anticipators, and mounting for T87F Thermostats. Q539 Subbases also provide system
and fan switching for heating, cooling, and heating-cooling thermostats. For subbase specifications, refer to Tables 1 and 2.
TABLE 1—SUBBASE SPECIFICATIONS.
Model Description
System
Switch
Fan
Switch Terminals
See
Fig.
Q539A provides system and fan switching and cooling
anticipator for heating cooling systems. Includes indicator
LOCKOUT LED for use in oil burner systems.
HEAT-
OFF-
COOL
AUTO-ON RH
-
RC-W-Y-G-X 3
Q539H provides fan switching with Z terminal for low voltage
fan switch to control fan in AUTO position.
NONE AUTO-ON R-W-Y-G-X-Z 4
Q539J provides system switching for control of heating and
cooling for heat pump and electric heating. Auto fan operates
through fan relay on both heating and cooling.
HEAT-
OFF-
COOL
AUTO-ON R-W-Y-G-X-P-O-B 5
TABLE 2—TERMINAL DESIGNATIONS.
Terminal Connection
R Transformer.
RC
a
Cooling Transformer.
RH
b
Heating Transformer.
W Heating Relay or Valve Coil.
Y Cooling Contactor Coil.
B
c
Heating Damper Motor or Changeover
Valve (if used).
O
d
Cooling Damper Motor or Changeover
Valve (if used).
G Fan Relay Coil.
X
e
Clogged Filter Switch or Lockout Switch
(primary control).
P Heat Pump Contactor Coil.
Z Q539H low voltage fan switch for control
of fan relay in AUTO position for both
heating and cooling control.
a
Cooling transformer in systems with separate heating and
cooling circuits.
b
Heating transformer in systems with isolated heating and
cooling circuits.
c
Circuit only completed between R and B with system
switch in HEAT position.
d
Circuit only completed between R and O with system
switch in COOL position.
e
Only available on subbases with indicator LEDs.
M3375
Mercury Notice
This control contains mercury in a sealed tube. Do not
place control in the trash at the end of its useful life.
If this control is replacing a control that contains mer-
cury in a sealed tube, do not place your old control in the
trash.
Contact your local waste management authority for
instructions regarding recycling and the proper disposal of
this control, or of an old control containing mercury in a
sealed tube.
Installation
WHEN INSTALLING THIS PRODUCT…
1. Read these instructions carefully. Failure to follow
instructions can damage product or cause a hazardous
condition.
2. Check ratings given in instructions and on product to
make sure product is suitable for your application.
3. Make sure installer is a trained, experienced service
technician.
4. After completing installation check out product opera-
tion as provided in these instructions.
LOCATION
Locate the subbase about 5 ft (1.5m) above the floor in
an area with good air circulation at average temperature.
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