Allied Lennox 4AC16LT Series Manual de instrucciones de instalación - Página 7

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Flushing Existing Line Set and Indoor Coil

This procedure should not be performed on systems

that contain contaminants, such as compressor burn

out.

Required Equipment

The following equipment is needed to flush the existing

line set and indoor coil (Figure 8). Two clean R-22 recovery

bottles, an oil-less recovery machine with a "pump down"

feature, and two sets of gauges (one for use with R-22 and

one for use with R410A).

Flushing Procedure

NOTE: The line set and/or indoor coil must be flushed with

at least the same amount of refrigerant that previously

charged the system. Check the charge in the flushing

cylinder before flushing the unit.

Remove existing R-22 refrigerant using the appropriate

procedure.

If the existing outdoor unit is not equipped with shutoff

valves, or if the unit is not operational AND the existing

R-22 refrigerant will be used to flush the system:

Disconnect all power to the existing outdoor unit. Connect

the existing unit, a clean recovery cylinder, and the

recovery machine according to the instructions provided

with the recovery machine. Remove all R-22 refrigerant

from the existing system. Refer to the gauges after

shutdown to confirm that the entire system is completely

void of refrigerant. Disconnect the liquid and suction lines

from the existing outdoor unit.

If the existing outdoor unit is equipped with manual shutoff

valves AND new R-22 refrigerant will be used to flush the

system:

Start the existing R-22 refrigerant system in cooling mode

and close the liquid line valve. Pump all the existing R-22

refrigerant back into the outdoor unit.

(It may be necessary to bypass the low pressure switches

to ensure complete refrigerant evacuation.)

When the low side system pressures reach 0 psig, close

the suction line valve. Disconnect all power to the existing

outdoor unit. Refer to the gauges after shutdown to confirm

that the valves are not allowing refrigerant to flow back

into the low side of the system. Disconnect the liquid and

suction lines from the existing outdoor unit.

Remove the existing outdoor unit. Set the new R410A

unit and follow the brazing connection procedure

outlined previously to make line set connections. Do

not install the R410A thermal expansion valve at this

time.

506467-01

Make low voltage and line voltage connections to the

new outdoor unit. Do not turn on power to the unit or

open the outdoor unit service valves at this time.

Remover the existing R-22 refrigerant flow control

orifice or thermal expansion valve before continuing

with flushing procedures. R-22 flow control devices

are not approved for use with R410A refrigerant and

may prevent proper flushing. Use a field-provided

fitting to reconnect the lines.

Remove the pressure tap valve cores from the

4AC16LT units service valves. Connect an R-22

cylinder with clean refrigerant to the suction service

valve. Connect the R-22 gauge set to the liquid line

valve and connect a recovery machine with an empty

recovery tank to the gauge set.

Set the recovery machine for liquid recovery and start

the recovery machine. Open the gauge set valves to

allow the recovery machine to pull a vacuum on the

existing system line set and indoor coil.

Invert the cylinder of clean R-22 and open its valve to

allow liquid refrigerant to flow in to the system through

the suction line valve. Allow the refrigerant to pass

from the cylinder and through the line set and the

indoor coil before it enters the recovery machine.

After all of the liquid refrigerant has been recovered,

switch the recovery machine to vapor recovery so that

all of the R-22 vapor is recovered. Allow the recovery

machine to pull a vacuum on the system.

NOTE: A single system flush should remove all of

the mineral oil from the existing refrigerant lines and

indoor coil. A second flushing may be done (using

clean refrigerant) if insufficient amounts of mineral oil

were removed during the first flush. After each system

flush, allow the recovery machine to pull a vacuum on

the system at the end of the procedure.

Close the valve on the inverted R-22 cylinder and the

gauge set valves. Pump the remaining refrigerant out

of the recovery machine and turn the machine off.

10. Use nitrogen to break the vacuum on the refrigerant

lines and indoor coil before removing the recovery

machine, gauges, and R-22 refrigerant drum. Re-

install pressure tap valve cores into the 4AC16LT

unit's service valves.

11. Install the refrigerant expansion valve approved for

use with R410A refrigerant in the liquid line at the

indoor coil.

Refrigerant Metering Device

4AC16LT units are designed for use with TXV systems

only.

Expansion valves equipped with Chatleff-type fittings are

available from the manufacturer. See Table 3 for proper

TXV for each unit.

Issue 1827

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