
18
Refrigeration(cont’d)
Thermostatic Expansion Valve
Location
This device is located on the same side as the refrigeration
stub.Abalancedportexpansionvalvemodelisfurnished
as a standard equipment, unless otherwise specied by
thecustomer
Expansion Valve Adjustment
Expansion valves must be adjusted to fully feed the
evaporator. Before attempting any adjustments, make
suretheevaporatoriseitherclearorverylightlycovered
withfrost,andthatthextureiswithin10°Fofitsexpected
operatingtemperature.
Measuring the Operating Superheat
1.Determinethesuctionpressurewithanaccu-
ratepressuregaugeattheevaporatoroutlet.
2.Fromarefrigerantpressuretemperaturechart,
determinethesaturationtemperatureatthe
observedsuctionpressure.
3.Measurethetemperatureofthesuctiongasat
thethermostaticremotebulblocation.
4.Subtractthesaturationtemperatureobtained
instepNo.2fromthetemperaturemeasuredin
stepNo.3.
5.Thedifferenceissuperheat.
6.Setthesuperheatfor5°F-7°F.
Evaporator Pressure Regulator
AnEvaporatorPressureRegulatorisinstalledinthefront
oftheself-servicesectiontomaintainaconstantdischarge
temperature.Itislocatedatthefrontrightsideofthecase,
underthefanplenumneartheTEXValve.
Service Case Temperature Control
TemperaturecontrolintheuppersectionoftheVR3with
the Sevice Option is done by means of a thermostat and
suction solenoid valve. This controls both temperature
andhumidity.
T-STAT Location
The T-STATS are located within the electrical raceway.
Refer to the wiring diagram(pg. 22-29). There are also
labelsonthebackofthecaseindicatingT-STATlocation(s).
Piping
Therefrigerantlineoutletsarelocatedunderthedeckpans.
Insulatesuctionlinestopreventcondensationdrippage.
Refrigeration Lines
Liquid Suction
3/8"O.D. 5/8"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 5/8”, 7/8”,
or 11/8”. Refer to the particular case you are hooking up.
Refrigerant lines should be sized as shown on the
refrigerationlegendfurnishedbythestore.
Install P-TRAPS(oiltraps)atthebaseofallsuctionline
verticalrisers.
Pressure dropcanrobthesystemofcapacity.Tokeepthe
pressuredroptoaminimum,keeprefrigerantlinerunas
shortaspossible,usingtheminimumnumberofelbows.
Whereelbowsarerequired,uselongradiuselbowsonly.
Control Settings
See VR3HV technical data sheet for the appropriate
settingsforyourmerchandiser.Maintaintheseparameters
toachievenearconstantproducttemperatures.Product
temperature should be measured first thing in the
morning,afterhavingbeenrefrigeratedovernight.Forall
multiplexing, defrost should be time terminated. Defrost
timesshouldbeasfollows:OFFCYCLE-Fourtimesdaily
for 30 minutes. The number of defrosts per day should
never change.The duration of the defrost cycle may be
adjustedtomeetconditionspresentatyourlocation.
Access to TX Valves and Drain Lines
Mechanical -Removeproductfromendofcase.Remove
product decks. Remove refrigeration and drain access
panels (labeled). TX valve (mechanical only) and drain
arelocatedundereachaccesspanelatendofthecase.
Electronic - TheElectronicExpansionvalvemasterand
slavecylinder(s)arelocatedwithintheelectricalaccess
panel(s).
Electronic Expansion Valve (Optional)
A wide variety of electronic expansion valves and case
controllers can be utilized. Please refer to EEV and
controller manufacturers information sheet. Sensors for
electronic expansion valves will be installed on the coil
outlet, and in the discharge air. (Some supermarkets
require a 3rd sensor in the return air). Case controllers
willbelocatedintheelectricalracewayorunderthecase.