hussmann P/N 0420057_B - Manual (Page 20)

Line Sizing
Refrigerant lines should be sized as shown on
the refrigeration legend that is furnished for the
store or according to ASHRAE guidelines.
Refer to the information on the next page for
branch line piping of Hussmann Equipment.
Oil Traps
P-traps (oil traps) must be installed at the base
of all suction line vertical risers.
Pressure Drop
Pressure drop can rob the system of capacity.
To keep the pressure drop to a minimum, keep
the refrigerant line run as short as possible
using a minimum number of elbows. Where
elbows are required,
USE LONG RADIUS ELBOWS
ONLY .
INSULATION
The suction and liquid lines should be clamped
or taped together and insulated for a minimum
of 30 ft (9144 mm) from the merchandiser.
Additional insulation for the balance of the
liquid and suction lines is recommended wher-
ever condensation drippage is objectionable or
lines are exposed to ambient conditions.
SUCTION LINE
• Pitch in direction of flow.
• May be reduced by one size at one third of
case run load and again after the second
third. Do not reduce below the case suction
line size.
• Case suction lines should enter at the top of
the branch line.
LIQUID LINE
• May be reduced by one size after one half
the case run load. Do not reduce below the
case liquid line connection size.
• Take-offs to case liquid lines should exit the
bottom of the branch liquid line. Provide an
expansion loop for each evaporator take-off.
(Minimum 3 in. [76 mm] loop.)
CONTROL SETTINGS
Merchandiser Technical Data Sheets (TDS) are
shipped with this manual. The TDS provide
case control settings and defrost data.
An evaporator pressure regulator or EPR
(primary control) and a 3 – 5ºF (1.7 – 2.7ºC)
differential thermostat (secondary control) must
control refrigeration temperature. The EPR
must be set to maintain the proper saturated
evaporator temperature as listed in the data
sheets. The thermostat must be set a couple
degrees colder than the discharge air tempera-
ture specified in the data sheets. The thermostat
will prevent product freezing should the EPR
temperature drift downward during reduced
load periods (lights off, lower ambient). The
thermostat will be wired to control the com-
pressor motor contactor (single compressor) or
a liquid line solenoid valve (parallel compressor
systems).
Defrost is Off Time. Defrost control settings are
listed in the data sheets. When these merchan-
disers are connected to parallel compressor
systems, a suction stop valve must be used to
isolate the evaporator during defrost periods.
2-2 R
EFRIGERATION
/ E
LECTRICAL
P/N 0420057_B
U.S. & Canada 1-800-922-1919 • Mexico 1-800-522-1900 • WWW.HUSSMANN.COM
Suction Line Return
Minimum Loop
3-in. (76 mm)
Liquid Line Take Off