PIPING
All piping must be clean and dry. Keep it capped to prevent dirt and moisture from entering.
Do not leave piping open to the atmosphere overnight. When brazing, keep dry nitrogen
flowing through the lines to prevent internal oxide and scale formation. Use a high
temperature silver brazing alloy. An off cycle pumpdown, with the room thermostat controlling
the liquid solenoid, is recommended, and is mandatory to maintain compressor warranty on
electric defrost systems.
Suction lines should slope a MINIMUM of 1/4 inch per foot in the direction of flow to insure oil
return. “P” traps must be used at the bottom of every suction riser and at 15 foot intervals. To
control compressor superheat and return gas temperature it may be necessary to insulate the
suction line, especially if long line runs are subjected to high ambient temperatures. Liquid-
suction line heat exchangers are often used with electric defrost systems and are highly
recommended to obtain optimum performance.
See page 6 and 7 for line sizing recommendations. Take caution not to undersize lines. The
liquid solenoid should be installed near the expansion valve inlet, inside the refrigerated space
or in the evaporator end housing. Secure the liquid line at the evaporator. When the liquid
solenoid opens and closes the liquid line experiences a “SHOCK” and tends to move
forcefully. Without proper support, the joints at the solenoid, expansion valve, distributor, and
distributor leads will fracture. Line supports are inexpensive compared to refrigerant loss and
downtime. All piping must be supported to prevent vibration and breaking. Tube clamps
should have a cushion surface for protecting the tubing.
Expansion valves should be selected from the valve manufacturers literature. If liquid
subcooling is present, be sure to use the correction factor to determine the correct size valve.
Avoid oversizing the valve which can cause hunting and floodback. On KS Electric Defrost
Systems, always use the expansion valves supplied with each evaporator. Read and retain the
expansion valve instructions. The expansion valve bulb must be clamped securely on the side
of a horizontal run of suction line, before any traps, preferably at the 4 o’clock or 8 o’clock
position. The bulb must be in complete contact with clean copper tube and must not bridge
any uneven surface. Use the bulb clamp supplied with the expansion valve. Take care not to
distort or crush the expansion valve bulb when tightening the clamp. See page 9 for
expansion valve adjustment recommendations.
The drain line should run directly from each evaporator and exit the freezer as quickly as
possible. It should be pitched a MINIMUM of 4 inches per foot. The drain line must always
be as large as the drain pan connection or larger. Do not reduce the drain line size. Some
evaporators defrost quickly and therefore a large volume of condensate must be drained
rapidly. There should be no traps or sharp changes of direction within the freezer. Drain lines
should have a trap where the ambient is always above 33°F or be protected from freezing by
continuous heating. The entire drain connection, drain line and trap may be heated and
insulated. Traps will prevent warm, moist air from being drawn up through the drain line,
which will form ice in the drain pan or on the bottom of the coil. Drain lines should run to an
open drain. They should never be directly connected to a sewer. Never let the condensate
run onto walkways or floors creating a safety hazard. Inspect the drain pan and connection
periodically to be sure it is clean and clear for free draining.
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