CeilAir CW series Manuel de l'opérateur télécharger pdf (Page 30)

(©July, 2008)

CeilAiR OHS Series Installation, Operation & Maintenance Manual

ir Technology Systems, Inc.

2-19

2.7.6 Remote Shut Down

NOTE

All wiring must be provided in accordance with local

and national electrical code requirements for Class 2

circuits.

Each unit is provided with a means to remotely shut

down the air conditioning unit. A normally closed

switch rated at 5 amperes at 24VAC is required for this

purpose. Two conductors from the normally closed

switch must be connected to the control terminal

board located within the unit electric box. Refer to the

supplied electrical schematic for proper wire termina-

tions.

2.8 Refrigerant Charging Procedures

Refrigerant charging procedures vary depending on the

type of refrigerant used in the unit. Before charging,

check the unit nameplate to confirm the refrigerant

type. If the unit operates with R22 refrigerant see

section 2.8.1. If R407C is used, see section 2.8.2.

NOTE

Refrigerant charging must be performed by a jour-

neyman, refrigeration mechanic or an air condi-

tioning technician.

2.8.1 R22 Refrigerant Charging Procedures

2.8.1.1 Self-Contained Systems

All self-contained water/glycol-cooled units (units that

require no refrigerant field piping) are factory charged

with R22. No field charging is required.

2.8.1.2 Remote Air-Cooled Split Systems (AR/AHU)

Remote air-cooled units are factory equipped with a

dry nitrogen holding charge, which must be removed

before piping and charging the unit.

PREPARING SYSTEM FOR CHARGING

1. Once all connections have been made, pressurize

the system to 150 psig with dry nitrogen. Leaks

may be detected by checking the standing

pressure.

2. After ensuring there are no leaks, relieve pressure

and evacuate the system. Pull a vacuum of 50

microns or less using the suction and discharge

service ports and the service port of the receiver (if

applicable). Hold the vacuum for 2 hours. Ensure

no portion of system has been isolated from the

evacuation process (liquid, suction or discharge

lines).

CAUTION

A proper vacuum must be drawn on the refriger-

ant system prior to charging. If this is not done

the refrigerant will combine with the moisture in

the pipes to form an acid that will eventually

cause compressor failure.

FINE TUNING THE SYSTEM CHARGE

2.8.1.2.1 0ºF Fan Cycling and -20ºF Variable

Speed Control

The following instructions are for charging systems

with condenser fan cycling or variable speed control

using R22 refrigerant.

1. Bleed air from hoses and "break" the system

vacuum by supplying R22 vapor. Supply R22

vapor to the suction port until the pressure is

raised to about 50 psig. This small holding charge

allows the low pressure switch to “make” through

out the process of fine tuning the system charge.

WARNING

Do not add liquid R22 refrigerant to suction side

of system.

2. Refrerring to Section 3.0, start the system and

use the microprocessor controller to lower the

temperature set-point 3-5°F below room tempera-

ture. This will ensure the cooling mode stays on

during the charging procedure.

CAUTION

An adequate heat load must be supplied to the

unit to ensure a proper charge.

3. Supply R22 vapor to the suction port until the

liquid line sight glass is cleared of all bubbles.

4. After the unit has stabilized, the liquid line sight

glass should be clear and the discharge pressure

should be a minimum of 200 psig. A superheat

reading should be taken near the feeler bulb from

the thermal expansion valve, ensuring the tem-

perature measuring device is well insulated. The

superheat should be approximately 12-15ºF.

5. A subcooling reading should be taken on the

output side of the condenser, with the tempera-

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CeilAir CW series Manuel de l'opérateur Page 30

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