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3.8 Connecting therefrigerant pipes

CAUTIONS DURING BRAZING

Replace air inside the tube with nitrogen gas to prevent copper oxide film from forming during the brazing process. (Oxygen, carbon dioxide
and Freon are not acceptable.)

●

Do not allow the tubing to get too hot during brazing.The nitrogen gas inside the tubing may overheat, causing refrigerant system valves to

become damaged. Therefore allow the tubing to cool when brazing.

●

Use a reducing valve for the nitrogen cylinder.

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Do not use agents intended to prevent the formation of oxide film. These agents adversely affect the refrigerant and refrigerant oil, and may

cause damage or malfunctions.

TIGHTENING

In the table below are shown the pipes diameter for each unit

For the flare nuts at tubing connections, be sure to use the flare nuts that were supplied with the unit, or else flare nuts for R410A. The refrige-
rant tubing that is used must be of the correct wall thickness as shown in the table below.
Because the pressure is approximately 1.6 times higher than conventional refrigerant pressure, the use of ordinary flare nuts or thin-walled
tubes may result in tube rupture, injury, or asphyxiation caused by refrigerant leakage.
In order to prevent damage to the flare caused by overtightening of the flare nuts, use the table above as a guide when tightening.

When tightening the flare nut on the liquid tube, use an adjustable wrench with a nominal handle length of 200 mm.

INSULATING THE REFRIGERANT TUBING

Thermal insulation must be applied to all units tubing, including distribution joint (field supply). For gas tubing, the insulation material must be
heat resistant to 120°C or above. For other tubing, it must be heat resistant to 80°C or above.
Insulation material thickness must be 10 mm or greater.
If the conditions inside the ceiling exceed DB 30°C and RH 70%, increase the thickness of the gas tubing insulation material by 1 step.

ø Tube

Tightening torque

Tube thickness

ø 6,35 (1/4”)

14 - 18 N*m

0,8 mm

ø 12,7 (1/2)”

49 - 55 N*m

0,8 mm

Unit

KRE-500DX1

KRE-1000DX1

Gas Pipe

ø 12,7 mm

Liquid Pipe

ø 6,35 mm

3.9 Connecting PRE-DX

• The electric heater shall be connected to the suction of fresh air stream, both upstream and downstream to a duct of the same nominal diam-

eter; the duct must be fully inserted on the heater sleeve up to the stop, so that it fits the airtight gasket.

• It is suggested to mount the heater as close as possible to the unit to which it is connected.

For PRE-DX heater the ambient temperature

must be from -25°C to +30°C; degree of protection IP40.

• The heater can be installed both horizontally and vertically; in case of horizontal electric heater, the electric box must be placed according to

one of the positions.

• The heater must be adequately supported, so that unit connections are free from any stress.
• The heater must not be insulated.

For BE heater, the supply air temperature must be lower than 50°C and the air speed must be higher than 2 m/s. Make sure that the
heater is turned ON only when the fan is switched on. The fan must continue to run at least 30 seconds after the heater has been
turned off.

• Connections and cables that are used for them have to be supplied by the installer.
• For power supply of the electric heater use a 3-wire cable (line, neutral, ground), sized for the specific current of the selected model. First,

pass along the free ends of the three cables from the inside of electrical board to the outside, through the glands on the basic unit.

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Flare insulator

Insulation tape (white)

Flare union

Unit side

Flare nut

Tube insulator

(not supplied)

Heat resistant

Insulation

Liquid tubing