Q539A, H and J Subbases
M3375
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
Q539A provides system and fan switching and cooling
anticipator for heating cooling systems. Includes indicator
LOCKOUT LED for use in oil burner systems.
Q539H provides fan switching with Z terminal for low voltage
fan switch to control fan in AUTO position.
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.
System
Switch
HEATOFFCOOL
NONE AUTO-ON R-W-Y-G-X-Z 4
HEATOFFCOOL
Fan
Switch Terminals
-
AUTO-ON RH
AUTO-ON R-W-Y-G-X-P-O-B 5
RC-W-Y-G-X 3
See
Fig.
TABLE 2—TERMINAL DESIGNATIONS.
Terminal Connection
R Transformer.
a
RC
Cooling Transformer.
b
RH
Heating Transformer.
W Heating Relay or Valve Coil.
Y Cooling Contactor Coil.
c
B
Heating Damper Motor or Changeover
Valve (if used).
d
O
Cooling Damper Motor or Changeover
Valve (if used).
G Fan Relay Coil.
e
X
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.
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 mercury 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.
®U.S. Registered Trademark
Copyright © 2002 Honeywell • • All Rights Reserved
95-6486-9
Do not mount the subbase where it may be affected by:
G
)
O
T
W
— drafts or dead spots behind doors or in corners.
— hot or cold air from ducts.
— radiant heat from the sun, fireplaces, or appliances.
— concealed pipes and chimneys.
— unheated (uncooled) areas such as an outside wall.
CAUTION
• Disconnect power supply to prevent electrical shock or equipment damage.
• Do not short across coil terminals on relay,
this can burn out the thermostat heat
anticipator.
• Do not overtighten captive mounting screws
because damage to subbase threads can result.
MOUNTING AND WIRING
Disconnect power supply before beginning installation to
prevent electrical shock or equipment damage.
All wiring must comply with local codes and ordinances.
1. In replacement applications, check the existing subbase wires for cracked or frayed insulation. Replace any
wires in poor condition. If the wire is plastered into the wall,
make a hole next to the wires and loosen the wires so that the
wires can be pushed back into the wall later.
2. In new installations, run wiring (if necessary) to the
subbase location.
IMPORTANT: To prevent interference with the thermostat
linkage, keep wire length to a minimum and run wires
as close as possible to the subbase.
3. Connect the wires to the terminals inside the subbase.
Refer to equipment manufacturer instructions for Q539
wiring diagrams. If not available, refer to Fig. 1 through 5.
4. Push excess wire back through the hole and plug any
opening with insulation to prevent drafts that can affect
performance.
5. Loosely fasten the thermostat subbase to the wall with
a screw through the left mounting hole. Adjust the subbase so
it is approximately level and start the second screw through
the right mounting slot. Do not tighten.
6. Level the thermostat subbase using a spirit level as
shown in Fig. 1.
7. Tighten mounting screws.
IMPORTANT: An incorrectly leveled subbase will cause
the temperature control to deviate from setpoint.
8. Mount and wire the thermostat to the thermostat subbase using the equipment manufacturer’s instructions.
Fig. 1—Level Q539 using a spirit level .
SPIRIT
LEVEL
PENING FOR
HERMOSTAT
IRING
LEVELIN
POSTS (2
MOUNTING
SLOTS
M3319A
Fig. 2—Barrier configuration.
FOR STRAIGHT
INSERTION–
STRIP 5/16 in. (8 mm)
SUBBASE TERMINAL SCREW
Fig. 3—Typical hookup for Q539A in heatingcooling application with remote lockout
indication.
HEAT
LOCKOUT
INDICATOR
LIGHT
X RH W Y G RC
SWITCH
BARRIER
Q539A/T87F INTERNAL SCHEMATIC
T87F
ADJUSTABLE
HEAT
ANTICIPATOR
OFF
COOL
HEAT
HEATING
CONTROL
W1
R1
OFF
COOLING
CONTROL
FOR WRAPAROUND–
STRIP 7/16 in. (11 mm)
TEMP.
FALL
Y1
FAN
AUTO
COOL
FAN
RELAY
M8831
FIXED COOL
ON
ANTICIPATOR
95-6486—9 2
HEATING
TRANSFORMER
1
L2 L2
1
(HOT) (HOT)
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
COOLING
TRANSFORMER
M8832
1
L1L1
Settings
SUBBASE SETTING
The subbase switching positions control the system
operation as described below.
SYSTEM SWITCH (some subbases do not have all of the
following functions):
COOL—cooling system is automatically controlled
by the thermostat. Heating system is off.
OFF—both the heating and cooling systems are off. If
the fan switch is at AUTO position, the cooling fan
is also off.
HEAT—heating system is automatically controlled
by the thermostat. Cooling system is off.
FAN SWITCH:
ON—fan operates continuously.
AUTO—fan operates with cooling equipment as con-
trolled by the thermostat or with the heating equipment as controlled by the plenum switch.
To move the subbase switches to the desired control
positions, use thumb and index finger to slide lever. Stop
lever must stop over desired function indicator position for
proper circuit operation.
Fig. 4—Typical hookup for Q539H in heating-
cooling application with remote switching
required to select heating or cooling and to
provide automatic fan operation.
Q539H/T87F INTERNAL SCHEMATIC
T87F
FILTER
LIGHT
X
REMOTE
SYSTEM
SWITCH
CLOGGED
FILTER SWITCH
OR COOLING
PANEL
CONNECTION
1
X TERMINAL IS USED ON Q539 MODELS WITH
FACTORY-INSTALLED MALFUNCTION LIGHT.
POWER SUPPLY. PROVIDE DISCONNECT
2
MEANS AND OVERLOAD PROTECTION AS REQUIRED.
ADJUSTABLE
HEAT
ANTICIPATOR
1
HEAT
COOL
HEATING
RELAY OR
VALVE
COIL
W Y
COOLING
CONTACTOR
COIL
R1
W1
TEMP.
FALL
Y1
AUTO
Z
EXTERNAL
SWITCHING
FOR AUTO
FAN
FAN
G
FAN
RELAY
ON
R
2
L1
L2
(HOT)
M8833
Fig. 5—Typical hookup for Q539J in heatingcooling applications. Fan relay operates
automatically on heat or cool with fan in AUTO
position
Q539J/T87F INTERNAL SCHEMATIC
T87F
FILTER
LIGHT
1
X
CLOGGED
FILTER SWITCH
OR COOLING
PANEL
CONNECTION
1
X TERMINAL IS USED ON Q539 MODELS WITH FACTORYINSTALLED MALFUNCTION LIGHT.
WITH NO O TERMONAL LOAD, THERMOSTAT CURRENT DURING
2
HEATING CYCLE VARIES DEPENDING ON WHETHER FAN SWITCH
IS IN THE ON OR AUTO POSITION. HEATER SHOULD BE SET FOR
COMBINED CURRENT LEVEL OF HEAT RELAY AND FAN RELAY COILS.
WITH O TERMINAL LOAD, SET THERMOSTAT HEAT ANTICIPATOR
TO ITS MAXIMUM SETTING. (LIMIT THE THERMOSTAT HEATING
LOAD CURRENT TO 0.8 AMPS TO ASSURE GOOD PERFORMANCE.)
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
3
PROTECTION AS REQUIRED.
HEAT
W
ELECTRIC
HEAT
RELAY
ADJUSTABLE
HEAT
ANTICIPATOR
OFF
COOL
Y
HEATING
DAMPER
MOTOR
COMPRESSOR
RELAY
3
L2
TEMP.
R1
FALL
Y1
W1
AUTO
OFF
COOL
HEAT
B R G
L1
(HOT)
O
COOLING
DAMPER
MOTOR
2
FAN
FAN
RELAY
ON
P
M8834
Checkout
When installation is complete, turn on power supply and
check system operation.
HEATING
Move the system switch on the Q539 to HEAT and the
fan switch to AUTO. Move the heating setpoint dial to about
6AC (10AF) above room temperature. Heating equipment
should start and the fan should run. Change the setpoint to
about 6AC (10AF) below the room temperature. The heating
equipment and fan should shut off.
NOTE: In heat pump applications, a minimum off-timer
provides a five-minute time delay before starting com-
pressor when the thermostat last turned off the compres-
sor, or when the system first received power. This delay
prevents compressor short cycling.
3 95-6486—9
COOLING
CAUTION
If outside air or heat exchange medium (water) is
below 10AC (50AF), do not operate cooling.
Move the system switch on the Q539 to COOL and the
fan switch to AUTO. Move the cooling setpoint dial to about
6AC (10AF) below room temperature. Cooling equipment
should start and the fan should run. Change the setpoint to
about 6AC (10AF) above the room temperature. The cooling
equipment and fan should shut off.
FAN
Move the subbase switch to OFF and the fan switch to
ON. The fan should run continuously. Move the fan switch
to AUTO. In this position, fan operation is controlled by the
heating or cooling system control circuit.
Operate the entire system one complete cycle with
switches in each position before leaving installation. Turn
thermostat dial to the desired setting and set the system and
fan switches.
Automation and Control Solutions
Honeywell Honeywell Limited—Honeywell Limitée
1985 Douglas Drive North 35 Dynamic Drive
Golden Valley, MN 55422 Scarborough, Ontario
95-6486–9 G.H. Rev. 8-02
M1V 4Z9
Printed in U.S.A. on recycled
paper containing at least 10%
post-consumer paper fibers.
www.honeywell.com/yourhome
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