Honeywell Q539A, H and J Subbases Installation Manual

Honeywell Q539A, H and J Subbases Installation Manual

Honeywell Q539A, H and J Subbases 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.

RCa

Cooling Transformer.

RHb

Heating Transformer.

W

Heating Relay or Valve Coil.

Y

Cooling Contactor Coil.

Bc

Heating Damper Motor or Changeover Valve (if used).

Od

Cooling Damper Motor or Changeover Valve (if used).

G

Fan Relay Coil.

Xe

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.

Honeywell Q539A 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

Level Q539 using a spirit level

Fig. 2—Barrier configuration.

Honeywell Q539A Barrier Configuration.PNG

Fig. 3—Typical hookup for Q539A in heatingcooling application with remote lockout indication.

Typical hookup for Q539A in heatingcooling application with remote lockout indication.

Honeywell Q539A 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 controlled 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.

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Honeywell Q539A, H and J Subbases Installation Manual