Fujitsu 18RLX, 24RLX, 42RLX, 36RLX Service Bulletin

FUJITSU GENERAL AMERICA, INC

SERVICE BULLETIN

353 Route West. Fairfield, NJ 07004
Ph: 973-575-0381 Fx: 973-836-0449

Number: 0006
Date: 9/22/09 Rev2

Em: [e-mail]

Type: Field

Fresh Air Intake w/ Compressor Operation OnlyPROBLEM

Duct Fan ControlSOLUTION

Production: All CassettesMODEL :18/24/36/42RLX Systems

1. Outline

The circuit shown below provides a cost effective solution for wiring a current switch
that monitors the compressor operation ON/OFF status and energizes the coil of a
relay which in turn close the contacts and provide line voltage to the duct fan. The
duct fan is required to introduce fresh (outside) air for ventilation.

2. Application

A third party current sensor switch with a built-in relay was
used in this application. The current sensor may be
installed around one of the compressor line voltage wires (Red,
Black or White).

3. Wiring diagram

IPM

24V DC

115V AC

+
_

Current Sensor

N.O.

N.O.

N.O.

Built in Relay

Compressor

Duct fan booster

4. Components utilized

Current sensor with built-in relay specifications:
Split Core Fixed Threshold Current Status Sensor with Command Relay and
Switching Power Supply.

FGAI Fresh Air Kit Part # KHRS940-25

5. Recommended Fan size.

Duct and Fan are field supply. A fan capable of generating 15 CFM at a
static pressure of approximately .26 inches W.C.

Wiring

•Recommended wire size- 14 AWG.

10A Fuse

(Field Supply)

Current Sensor Installation

• Install the current sensor around one of the compressor line voltage
wires.

• Tuck sensor into the clearance behind the compressor wire molex
plug.

• Secure the current sensor with a zip tie.

Secure Current Sensor

1

3

2

4

1

3

2

4

• 4 zip ties are needed for correct installation.

• Secure the current sensor wires with all four zip ties according to the
arrows. Do not tie around any of the copper lines.

•Cut the ends of the zip ties.

CASSETTE

CEILING CASSETTE

OUTSIDE (FRESH) AIR INTAKE

58.8 Pa
.24 in W.C.

15 CFM

4” Duct

Outside (Fresh)

Air Intake

Fan

2.75” x 4”

Field Supplied

Transition

Fan Static Pressure Requirements:

Static pressure required at Cassette = .24 in W.C.
25 ft. 4” duct + intake=45ft. TEL x .04/100 = .018 in W.C.

TOTAL =.258 in W.C.

Fan Selection:

Select fan to deliver 15 CFM @ approximately .26 in W.C.
Static pressure requirements will vary with duct length and
inlet conditions.

NOTE: Filter for outside air required. Add filter static pressure loss to static
pressure requirements above.