Heatcraft Mohave, Installation & Operation Manual, Page: 12 / 76

12
Recommended Refrigerant Piping Practices
The system as supplied by
Heatcraft Refrigeration Products
, was
thoroughly cleaned and dehydrated at the factory. Foreign matter may enter the
system by way of the evaporator to condensing unit piping. Therefore, care must
be used during installation of the piping to prevent entrance of foreign matter.
Install all refrigeration system components in accordance with applicable local and
national codes and in conformance with good practice required for the proper
operation of the system.
The refrigerant pipe size should be selected from the tables on pages 15-21. The
interconnecting pipe size is not necessarily the same size as the stub-out on the
condensing unit or the evaporator.
The following procedures should be followed:
(a)
Do not leave dehydrated compressors or filter driers open to the
atmosphere.
(b) Use only refrigeration grade copper tubing, properly sealed against
contamination.
(c) Suction lines should slope 1/4" per 10 feet towards the compressor.
(d) Suitable P-type oil traps should be located at the base of each
suction riser to enhance oil return to the compressor.
(e) For desired method of superheat measurement, a pressure tap
should be installed in each evaporator suction line in the proximity of
the expansion valve bulb.
(f)
When brazing refrigerant lines, an inert gas should
be passed through the line at low pressure to prevent
scaling and oxidation inside the tubing. Dry nitrogen is
preferred.
(g) Use only a suitable silver solder alloy on suction and liquid lines.
(h) Limit the soldering paste or flux to the minimum required to prevent
contamination of the solder joint internally. Flux only the male portion
of the connection, never the female. After brazing, remove excess flux.
(i) If isolation valves are installed at the evaporator,full port ball valves
should be used.
(j) Do not install liquid/suction line heat exchangers.
Refrigerant Pipe Support
1. Normally, any straight run of tubing must be supported in at least two locations
near each end of the run. Long runs require additional supports. The refrigerant
lines should be supported and fastened properly. As a guide, 3/8 to 7/8 should be
supported every 5 feet; 1-1/8 and 1-3/8 every 7 feet; and 1-5/8 and 2-1/8 every
9 to 10 feet.
2. When changing directions in a run of tubing, no corner should be left
unsupported. Supports should be placed a maximum of 2 feet in each direction
from the corner.
3. Piping attached to a vibrating object (such as a compressor or compressor base)
must be supported in such a manner that will not restrict the movement of the
vibrating object. Rigid mounting will fatigue the copper tubing.
4. Do not use short radius ells. Short radius elbows have points of excessive stress
concentration and are subject to breakage at these points.
5. Thoroughly inspect all piping after the equipment is in operation and add
supports wherever line vibration is significantly greater than most of the other
piping. Extra supports are relatively inexpensive as compared to refrigerant loss.
Piping
Example of Pipe Support Condensing Unit / Compressor to Wall Support.