Precautions When Reusing Existing R22 Refrigerant Pipes - Mitsubishi Electric Mr.Slim PUHZ-SHW80VHA Service Manual

2-3. PRECAUTIONS WHEN REUSING EXISTING R22 REFRIGERANT PIPES

(1) Flowchart
The existing pipe thickness meets speci-
fications and the pipes are not damaged.
Check if existing air conditioner can operate.
Existing air conditioner can
operate.
Perform cooling operation
for about 30 minutes and
then do a pump down work.
Disconnect existing air con-
ditioner from piping.
Existing pipes can be reused.
Connect a new air conditioner.
●The air conditioner automatically performs cooling operation through replace filter for about 2 hours.
Connecting a new air conditioner
Flaring work should be done so that flare meets the dimension for R410A.
Use flare nut provided with indoor and outdoor unit.
When using gas piping of 19.05mm for SHW112, 140.
Make sure that DIP SW8-1 on outdoor unit controller board is set to ON.
This is to keep the pressure on pipes within permissible range.
● Use different diameter joint or adjust the piping size by brazing.
When using pipes larger than specified size for SHW80.
Make sure that DIP SW8-1 on outdoor unit controller board is set to ON.
This is to prevent oil flow ratio from lowering due to the decrease in flowing refrigerant.
● Use different diameter joint or adjust the piping size by brazing.
When existing pipes are specified size.
The pipes can be reused.
● Use different diameter joint or adjust the piping size by brazing.
OCH526
Measure the existing pipe thickness and check for damage.
Existing air conditioner
cannot operate.
Use a refrigerant recovery
equipment to recover the
refrigerant.
In case existing pipes were used
for gas or oil heat pump system,
be sure to clean the pipes.
5
The existing pipe thickness does not meet
specifications or the pipes are damaged.
Existing pipes cannot be
reused. Use new pipes.
SHW·HA