035-18549-000-B-0402
12
Unitary Products Group
If the unit has already lost its holding charge, it should
be leak tested and the necessary repairs should be
made. If the unit has maintained its holding charge, you
can assume that it has no leaks and proceed with the
installation.
Before installing the liquid line between the outdoor
and indoor units, remove the copper disc from the liq-
uid connection on the outdoor unit per the following
procedure:
1.
Make sure the refrigerant in the line has been
recovered and that the liquid service valve on the
unit is front-seated and closed. The valve stem
should be turned to its maximum clockwise posi-
tion.
2.
Drill a small hole through the disc before unbrazing
it to permit a flow of dry nitrogen through the con-
nection while it is being unbrazed.
3.
Remove the cap from the 1/4" access port on the
liquid line stop valve.
4.
Connect a supply of dry nitrogen to this access
port.
5.
Unbraze the copper disc from the liquid connection
while maintaining a minimum flow of dry nitrogen
through the connection.
After the disc has been removed,
1.
Burnish the external surfaces of the liquid connec-
tion on the outdoor unit and the end of the field-
supplied piping being used for the liquid line.
NOTE: Clean surfaces are essential for a well brazed
connection.
2.
Carefully clean the internal surfaces of the above.
Any particles left on these surfaces may lead to a
future system malfunction.
NOTE: Use only copper tubing that has been espe-
cially cleaned and dehydrated for refrigerant
use. If the tubing has been open for an
extended period of time, it should be cleaned
before being used.
The liquid line connections can now be brazed while
maintaining a minimum flow of dry nitrogen through the
piping.
NOTE: A filter-drier is factory-mounted in the outdoor
unit for the heating cycle and in the indoor unit
for the cooling cycle.
Do NOT install another filter-drier in the field-
supplied liquid line because refrigerant will
flow in both directions on a heat pump system.
1.
The matched air handlers are shipped with a small
R-22 charge and they should be checked for leaks
before installation. Drill a small hole through the
sealing cap or disc in both the liquid and suction
connection. If there is a pressure release, the
evaporator has no leaks and you can proceed with
installation. If the charge has been lost, the coils
should be leak tested and the necessary repairs
made.
2.
Move the dry nitrogen supply from the access port
on the liquid line service valve of the outdoor unit to
the hole through the vapor disc on the indoor unit.
When making a braze connection, wrap a wet
rag around all tubing inside the unit to prevent
damage to the other components.
Dry
nitrogen
should
always
be
supplied
through a connection while it is being brazed or
unbrazed because the temperature required to
make or break a brazed joint is sufficiently high
to cause oxidation of the copper unless an inert
atmosphere is provided. The flow of nitrogen
should be continued until the joint has cooled.
The dry nitrogen must always be supplied
through a pressure regulating valve.
This hole is also required to prevent the inter-
nal pressure from building up as the disc is
being unbrazed and from blowing the disc off.
This
warning
applies to
any disc being
removed from a service valve, coil connection,
etc.