Bulletin 30-20 — Page 11
© Copyright 2010, Unico, Inc.
minate the secondary drain line above a windowsill so
that the drainage splashes on the window. This will serve
as an indicator that there is a problem with the primary
drain. In cases where a secondary drain line cannot be
run, add a float switch or a micro switch with a paper
fuse.
Refrigerant Coil Connections
Note
All refrigerant coils are shipped from
our factory pressurized with nitrogen.
They do not contain any refrigerant.
WARNING
To prevent injury to eyes, face away
from the Schrader valve when releasing
nitrogen gas.
The refrigerant coils are equipped with a Schrader valve
port to relieve the pressure and for factory testing pur-
poses. It can also be used to check for leaks prior to in-
stallation. Unscrew the Schrader cap and press the de-
pressor. If there is no nitrogen pressure present, the
coil may have developed a leak during shipment and
should be returned to the point of purchase for ex-
change. If pressure is present, then go ahead and relieve
the pressure in the coil be continuing to press on the de-
pressor. When all the pressure is removed cut the ends of
the connections off.
Cut end of connection as shown.
Connection after the end has been cut off.
WARNING
To prevent injury, remove all pressure
from coil before removing connection
end caps.
CAUTION
When brazing, purge with nitrogen gas
to prevent the formation of oxides.
The refrigerant lines are copper sweat connections. The
liquid line is 3/8-inch (9.5mm) OD and the suction line
is 7/8-inch (22mm) OD. Refer to the condensing unit
manufacturer’s instruction for proper line sizing infor-
mation based on distance from condenser.
Install a liquid line filter drier as close to the coil module
as possible to protect the evaporator from foreign object
debris. For attic installations or when using long line
sets, an optional moisture indicating sight glass should
also be installed between the filter-drier and expansion
valve, near the indoor unit.
All refrigerant coils require a thermostatic expansion
valve. The valve is shipped loose and should be attached
prior to charging. If the system will be using R-410a, be
sure to use the R-410a valve; these can be ordered sepa-
rately as shown in Table 6. Always use new Teflon seals
when replacing the TXV (Unico Part No. A00809-001).
Remove nut as shown.
Remove side panels as shown.
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