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12.4.2. Transferring (Using New Refrigerant Piping)
1. Removing the unit
a. Collecting the refrigerant into the outdoor unit by pumping down
The refrigerant can be collected into the outdoor unit (pumping down) by pressing the TEST RUN button, even when the
temperature of the room is low.
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Check to make sure that the valve stems of the 2-way valve and 3-way valve have been opened by turning them counter-
clockwise. (Remove the valve stem caps and check to see that the valve stems are fully opened position. Always use
a hex wrench (with 4-mm opposing sides) to operate the valve stems.)
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Press the TEST RUN button on the indoor unit, and allow preliminary operation for 5-6 minutes. (TEST RUN mode)
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After stopping the operation, let the unit sit for about 3 minutes, then close the 2-way valve by turning the valve stem in
the clockwise direction.
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Press the TEST RUN button on the indoor unit again, and after 2-3 minutes of operation, turn the valve stem of the 3-
way valve quickly in the clockwise direction to close it, then stop the operation.
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Tighten the caps of the 2-way valve and 3-way valve to the stipulated torque.
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Remove the connection pipes (liquid side and gas side).
b. Removing the indoor and outdoor units
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Disconnect the pipes and connecting electric cables from between the indoor and outdoor units.
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Put capped flare nuts onto all of the pipe connections of the indoor and outdoor units, to make sure no dust or other
foreign matter enters.
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Remove the indoor and outdoor units.
2. Installing the unit
Install the unit using new refrigerant piping. Follow the instructions in section 4.1 to evacuate the pipes connecting the indoor
and outdoor units, and the pipes of the indoor unit, and check for gas leaks.
12.4.3. AC Units Replacement (Using Existing Refrigerant Piping)
When replacing an R410A AC unit with another R410A AC unit, you should re-flare the refrigerant piping. Even though the
replacement AC unit uses the R410A, problems occur when, for example, either the AC unit maker or the refrigerating machine oil
is different.
When replacing an R22 AC unit with an R410A AC unit, the following checks and cleaning procedures are necessary but are
difficult to do because of the chemical characteristics of the refrigerating machine oil (as described in items c) and d) of section
About R410A Refrigerant
). In this case, you should use new refrigerant piping rather than the existing piping.
1. Piping check
Because of the different pressure characteristics of R22 and R410A, the design pressure for the equipment is 1.6 times
different. The wall thickness of the piping must comply with that shown in Table 10, but this is not easy to check. Also, even if
the thickness is correct, there may be flattened or bent portions midway through the piping due to sharp curves. Buried sections
of the piping also cannot be checked.
2. Pipe cleaning
A large quantity of refrigerating machine oil (mineral oil) adheres to existing pipes due to the refrigeration cycle circulation. If the
pipes are used just as they are for the R410A cycle, the capacity will be lowered due to the incompatibility of this oil with the
R410A, or irregularities may occur in the refrigeration cycle. For this reason, the piping must be thoroughly cleaned, but this is
difficult with the present technology.
12.4.4. Refrigerant Compatibility (Using R410A Refrigerant in R22 ACs and Vice Versa)
Do not operate an existing R22 AC with the new R410A refrigerant. Doing so would result in improper functioning of the equipment
or malfunction, and might lead to a major accident such as an explosion in the refrigeration cycle. Similarly, do not operate an
R410A AC with R22 refrigerant. The chemical reaction between the refrigerating machine oil used in R410A ACs and the chlorine
that is contained in R22 would cause the refrigerating machine oil to degrade and lead to malfunction.
12.4.5. Recharging Refrigerant During Servicing
When recharging is necessary, insert the specified amount of new refrigerant in accordance with the following procedure.
1. Connect the charging hose to the service port of the outdoor unit.
2. Connect the charging hose to the vacuum pump adaptor. At this time, fully open the 2-way valve and 3-way valve.
3. Fully open the handle Lo of the manifold gauge, turn on the power of the vacuum pump and continue the vacuum process for
at least one hour.
4. Confirm that the low pressure gauge shows a reading of -0.1 Mpa (-76 cmHg), then fully close the handle Lo, and turn off the
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