When brazing couplings, ensure the following:
1. When applying paste flux to the copper tube, avoid applying excessive amounts. This
prevents flux running inside the coupling where it can cause corrosion and damage.
2. Immerse the coupling in a cold water bath, ensuring the diaphragm (threaded) is fully
immersed.
3. Double-tipped torches are recommended to reduce brazing time. After brazing, quench the
couplings to reduce the temperature.
When assembling the couplings ensure the following:
1. Use clean oil.
2. The refrigerant oil is applied to the entire diaphragm surface, O-ring, and threaded male
coupling end.
3. Before starting the threads of the female coupling nut onto the male half, coupling halves
must be held in proper alignment with each other. Thread by hand the first three rotations
of the union nut. If the nut does not start by hand, adjust the position of the line set or, if
necessary, the unit module's position.
4. Use a backup wrench to tighten the female union nut until a definite increase in resistance is
felt. At this point, most of threads have been covered by the nut. Ensure that the female and
male bodies do not rotate at any point in the wrench installation.
5. Make a note of the location of the female nut to the bulkhead. Use a marker or scribe to mark
a line lengthwise. Finally, tighten an additional one wrench flat or 60°. This final tightening is
necessary to ensure a proper leakproof seal between the couplings.
Interconnecting refrigerant tubing
After the evaporator and condenser sections are mounted, the interconnecting refrigerant tubing
can be fabricated. For cooling systems where the indoor and outdoor sections are installed at the
same elevation, the refrigerant line sizes usually can be matched with factory supplied fittings. See
Table 3.
Note:
There are exceptions for total line lengths exceeding 75 feet where pressure drop
limitations are exceeded. For further information, refer to
General Piping Recommendations and
Refrigerant Line Length (Form 247077-UAD-H-0209)
.
The following guidelines apply to field fabricated piping:
•
Use hard drawn refrigeration type copper tubing where no appreciable amount of bending
around pipes or obstructions is necessary. If soft copper must be used, take care to avoid
sharp bends that may cause a restriction. Route refrigerant tubing for minimum linear length
and minimum number of bends and fittings. The use of long radius elbows for all 90° bends
is recommended.
•
Braze all copper to copper joints with brazing rod high in silver or equivalent brazing
material. DO NOT USE SOFT SOLDER.
•
During brazing operations, flow an inert gas such as nitrogen through the system to prevent
internal scaling and contamination.
If the piping is properly sized, traps are not required. They only increase the pressure drop across
the system, further reducing capacity.
17
Model DSH024C–120C Horizontal R-410A Air Conditioning Units C-Generation Smart Equipment Controller
Johnson Controls
