Refrigeration; Condenser Ventilation - Hussmann RGD Installation And Operation Manual

Rev.0106
REFRIGERANT TYPE
The standard refrigerant will be R-22 unless otherwise
specified on the customer order. Check the serial plate
on the case for information.
PIPING
The refrigerant line outlets are located under the fixture
at the left hand end when viewed from the back. Insulate
the suction lines to prevent condensation leakage.
REFRIGERATION LINES
LIQUID
3/8" O.D.
NOTE: The standard coil is piped at 5/8" (suction);
however, the store tie-in may vary depending on
the number of coils and the draw the case has.
Depending on the case setup, the connecting point
in the store may be
5 7 1
/ ", / ", or 1 / ". Refer to the particular case you
8 8 8
are hooking up.
Refrigerant lines should be sized as shown on the refrig-
eration legend furnished by the store.
Install P-traps (oil traps) at the base of all suction line ver-
tical risers.
Pressure drop can rob the system of capacity. To keep the
pressure drop to a minimum, keep refrigerant line run as
short as possible, using the minimum number of elbows.
Where elbows are required, use long radius elbows only.
CONTROL SETTINGS
See the "Case Specs" section of this guidebook for the
appropriate settings for your merchandiser. Maintain these
parameters to achieve near constant product tempera-
tures. Product temperature should be measured first thing
in the morning, after having been refrigerated overnight.
For all multiplexing, defrost should be time terminated.
Defrost times should be as follows: OFF CYCLE - One
time daily for 110 minutes. The number of defrosts per
day should never change. The duration of the defrost cycle
may be adjusted to meet conditions present at your loca-
tion.
ACCESS TO TX VALVES & DRAIN LINES
MECHANICAL - Remove product from the case. Remove
product racks (if applicable). Remove refrigeration and drain
access panels (labeled). TX valve (mechanical only) and drain
are located under each access panel at end of the case.
ELECTRONIC - The Electronic Expansion valve master and
slave cylinder(s) are located within the electrical access
panel(s).
ELECTRONIC EXPANSION VALVE (OPTIONAL)
A wide variety of electronic expansion valves and case
controllers can be utilized. Please refer to EEV and con-
troller manufacturers information sheet. Sensors for elec-
SUCTION
5/8" O.D.

Refrigeration

tronic expansion valves will be installed on the coil inlet,
coil outlet, and in the discharge air. (Some supermarkets
require a 4th sensor in the return air). Case controllers
will be located in the electrical raceway or under the case
THERMOSTATIC EXPANSION VALVE LOCATION
An Alco balanced port expansion valve model is furnished
as standard equipment, unless otherwise specified by cus-
tomer. There is one expansion valve located on the right
side of each evaporation coil under the bottom deck pans.
EXPANSION VALVE ADJUSTMENT
Expansion valves must be adjusted to fully feed the evapo-
rator. Before attempting any adjustments, make sure the
evaporator is either clear or very lightly covered with frost,
and that the fixture is within 10 F of its expected operat-
ing temperature.
MEASURING THE OPERATING SUPERHEAT
1. Determine the suction pressure with an accurate
pressure gauge at the evaporator outlet.
2. From a refrigerant pressure temperature chart,
determine the saturation temperature at the
observed suction pressure.
3. Measure the temperature of the suction gas at the
thermostatic remote bulb location.
4. Subtract the saturation temperature obtained in step
No. 2 from the temperature measured in step No. 3.
3. The difference is superheat.
5. Set the superheat for 5 F - 7 F.
FAN SPEED CONTROL
Located in the electrical raceway on the lower right end
is a fan speed control. This control is set at the factory for
maximum. To adjust, turn the knob clockwise to obtain
approximately 50 FPM air speed. This may vary due to
store ambient conditions, especially the relative humidity.
With low humidity, slow the fan. With high humidity con-
ditions, set the control for maximum. Each case has its
own control and allows independant settings in case line-
ups.
NOTE: Slow air picks up more humidity from coil and ice.

Condenser Ventilation

Be sure to supply adequate ventilation for the condenser
in Self Contained units. Allow 150 square inches for units
up to 1 1/2 h.p., and 200 for condensr units over 2 h.p.
7