Armstrong Air 4SCU 16LS Series, Инструкция по установке и обслуживанию

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506859-01 Issue 1236 Page 10 of 32
4. Remove 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 R-410A refrigerant and may
prevent proper flushing. Use a field-provided fitting to
reconnect the lines.
5. Remove the pressure tap valve cores from the
4SCU16/18LS 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 maching with an empty
recovery tank to the gauge set.
6. 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.
7. 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.
8. 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 sytem.
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.
9. 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 4SCU16/18LS unit’s service
valves.
11. Install the fixed orifice (or thermal expansion valve
approved for use with R-410A refrigerant) in the liquid
line at the indoor coil.
Refrigerant Metering Device
4SCU16/18LS units are designed for use with TXV systems.
Refer to the appropriate following section for information on
installing the chosen refrigerant metering device.
An R410A system will not operate properly with an R-22
metering device.
Install the refrigerant metering device as shown in Figure
12. Do not twist cap tubes when loosening the seal nut from
the orifice housing. Use wrench to back up the distributor.
Expansion Valve Systems
Expansion valves equipped with Chatleff-type fittings are
available from the manufacturer. See Table 3 for proper
TXV for each unit.
To install an expansion valve (See Figure above):
1. Separate the distributor assembly and remove the piston
orifice and used teflon seal. Insert nozzle end of the
expansion valve along with a new teflon seal into the
distributor and tighten to 20 - 30 ft. lbs. Use backup
wrench on all wrench flats.
Overtightening will crush
the teflon seal and may cause a leak.
2. Attach liquid line portion of distributor assembly along
with new teflon seal to the inlet of the expansion valve.
Tighten to 20 - 30 ft. lbs. Use backup wrench on all
wrench flats. Overtightening will crush the teflon
seal and may cause a leak.
Figure 12
Table 3
Model Part NUMBER
4SCU16LT-24-36 A4TXV01
4SCU16LT-48 A4TXV02
4SCU16LT-60 H4TXV03
4SCU18LT-18, -24, -30 A4TXV01
4SCU18LT-36, -42 A4TXV02
4SCU18LT-48, -60 H4TXV03
TXV Data