GENERAL DESCRIPTION
34
Chamber Cooling (2 HP – 3.5 HP systems)
After passing the bypass tee, the liquid refrigerant flows through the liquid line solenoid (item 110), and
into the thermostatic expansion valve (item 111) where it changes to a low pressure, two phase
refrigerant. The two phase refrigerant is cold due to the flashing of refrigerant. The two phase
refrigerant enters the distributor (item 112) where the refrigerant is evenly distributed to evaporator
circuits. The evaporator (item 113) serves to boil the rest of the R-410A into a vapor. This boiling action
cools the chamber. If dehumidification is called for, some of the R-410A refrigerant is diverted to the
humidity loop prior to entering the thermostatic expansion valve (see Humidity Loop section).
Superheated refrigerant vapor exits the evaporator and moves through the suction line. (3.5 HP units) A
crankcase pressure regulator is located close to the compressor to keep the compressor suction from
rising above a preset factory pressure. A suction service valve (item 115) is located near the
compressor.
Chamber Cooling (6 HP – 15 HP systems)
After passing the bypass tee, the liquid refrigerant flows through the maximum liquid line solenoid (item
110), and into the maximum thermostatic expansion valve (item 111) where it changes to a low-
pressure two phase refrigerant. In parallel with the maximum valve, liquid refrigerant flows through a
minimum liquid line solenoid (item 119), and into the minimum thermostatic expansion valve (item 120)
where it also changes to a low pressure, two phase refrigerant. The two phase refrigerant is cold due to
the flashing of refrigerant. The two phase refrigerant enters the distributor (item 112) where the
refrigerant is evenly distributed to evaporator circuits. The evaporator (item 113) serves to boil the rest
of the R-410A into a vapor. This boiling action cools the chamber. If dehumidification is called for, some
of the R-410A refrigerant is diverted to the humidity loop prior to entering the thermostatic expansion
valve (see Humidity Loop section).
Superheated refrigerant vapor exits the evaporator and moves through the suction line. A crankcase
pressure regulator is located close to the compressor to keep the compressor suction from rising above
a preset factory pressure. A suction service valve (item 115) is located near the compressor.
Humidity Loop (Optional Equipment)
When dehumidification is called for while in humidity mode, some of the liquid refrigerant is diverted to
the humidity loop. The refrigerant passes through the wet coil solenoid valve (item H127) and a wet coil
capillary tube (item H123). Two phase refrigerant exits the capillary tube and enters the evaporator
(item H125). The evaporator is cold enough to attract moisture from the chamber air, but not cold
enough to freeze water on the evaporator. The temperature of the evaporator is regulated by an
evaporator pressure regulator valve (item H126) E.P.R. for short. This valve is intended to flood the coil
to keep pressure higher than the suction pressure. The warm chamber air keeps the moisture from
freezing on the coil. After the refrigerant leaves the wet coil, it enters the suction line and returns to the
compressor.
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