Friedrich R-410A service manual Connecting a Remote Wall Thermostat

Low Voltage Interface Connector

WARNING

ELECTRIC SHOCK HAZARD

Disconnect power to the unit before servicing. Failure to follow this warning could result in serious injury or death.

All Kuhl and Kuhl + units have a low voltage interface connector through which a Remote Wall Thermostat, Desk Control and Auxiliary Fan’s Relay can be connected. The interface connector is located on the left side behind the decorative front cover.

Interface Connector Location

Figure 1

Table 1

	Interface Connector Definitions
	Front Panel. Wire jumper between FP and
FP	F2 enables front panel operation. Jumper off
	enables remote wall t-stat operation.
F2	Used with F1 to provide 24 VAC to external
	fan relay. (See above for use with FP)
F1	Used with F2 to provide 24 VAC to
	external fan relay.
D2	Used with D1 for desk control on or off
	operation.
D1	Used with D2 for desk control on or off
	operation.
C	Common Ground Terminal
GH	Call for high fan
GL	Call for low fan
B	Call for heat pump reversing valve
Y	Call for compressor
W	Call for heating
R	24V Power from Electronic Control to Wall

Adding a Remote Wall Thermostat

An external thermostat may be added to the air conditioner to provide remote temperature sensing and control.

Thermostat Selection

Friedrich recommends the use of either the Friedrich RT4 or RT5. These thermostats are single stage heat/cool, manual changeover. The RT4 is a digital display thermostat with single speed fan control. The RT5 features a digital display, two fan speed selection, filter check light, temperature limiting, status indicator light, room temperature offset, backlight and battery backup. Other thermostats may be used as long as they are single stage heat/cool and are configured correctly for the unit.

Thermostat terminals requirements:

For cooling only units: C, R, G, Y.

For cooling with electric heat units: C, R, G, Y, W.

For heat pump units: C, R, G, Y, W, B.

For two fan speeds, thermostat must have 2 fan speed selection.

During Heat Pump Mode:

The B terminal must be continuously energized. The W terminal must have 24 VAC output to call for heat. The control board decides on whether to turn on the Heat Pump Heat (compressor) or Electric Heat. The Y terminal should not have 24 VAC output during heat mode.

Connecting a Remote Wall Thermostat

To enable the remote thermostat operation, remove the jumper between terminals FP & F2 on the interface connector. Connect the thermostat using Figure 1 and Table 1 as a guide.

Procedure

1)Unplug the unit.

2)Unscrew and remove the decorative front cover. (Page 30)

3)Locate the Interface Connector (24 VAC terminal strip (See figure 1 at left) and remove the jumper wire at FP and F2.

4)Make the wire connections according to the configuration needed for your unit (see above or page 68 for wiring diagrams).

5)Once each wire is matched and connected, the unit is now ready to be controlled by the thermostat.

6)Reattach the decorative front cover (see page 30).

Note: Under T-Stat operation the front panel is disabled except the Maintenance functions (see page 29 for details).

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