GENERAL DESCRIPTION
Page 2-26
REFRIGERATION SYSTEM
Model #: MCB(H)-1.2-.33-H/AC (115V and 230V)
Single Stage System (Refrigerant R-404A) - Refer to drawing: MCB-RF03
The compressor (item 1) will pump compressed R-404A vapor through the discharge line. The discharge
refrigerant vapor enters the air-cooled condenser.
The air-cooled condenser (item 5) cools the high pressure R-404A vapor and condenses it into a high-
pressure liquid. The condenser fan motor will be energized anytime System 1 is running.
High-pressure liquid refrigerant exits the condenser. The liquid • ows through a receiver • lter-drier, sight glass,
a tee for the wet coil, and into the main cooling solenoid valve (item 10) and then the T.E.V. (item 11) where
it changes to a low-pressure two-phase refrigerant. The two phase refrigerant is cold due to the • ashing of
refrigerant. It enters the evaporator (item 13) where it cools the chamber and boils the rest of the R-404A into
a vapor.
Superheated R-404A vapor exits the evaporator and moves through the system 1 suction line. A service port
is located near the compressor.
Control System
REFRIGERATION (Refer to drawing: MCB-RF03 & MCB(H)-EW02)
Mode: Normal cooling
When there is call for cooling the R-404A compressor turns on, 1-SOL is energized.
When there is a call for cooling refrigerant (R-404A) • ows through the solenoid (1-SOL) and the T.E.V. into
the evaporator and cools the chamber. When the chamber is near the set point the controller begins to cycle
1-SOL on and off. When 1-SOL is turned off, 4-SOL is energized allowing refrigerant to by-pass back to the
suction line.
Mode: Humidity
When Dehumidi• cation is called for, Solenoid H-11 SOL is energized. The refrigerant passes through a
solenoid valve (item H27) and a Wet Coil capillary tube (item H23). Two phase refrigerant exits the Capillary
tube and enters the wet coil (item H25). The wet coil is cold enough to attract water from the chamber air,
but not cold enough to freeze the water on the coil. The temperature of the coil is regulated by a pressure
regulating E.P.R. valve (item H26). The E.P.R. valve is set at 68 psig (4.7 barG) which corresponds to a 29°F
(-16°C) wet coil temp. The warm chamber air keeps the moisture from freezing on the coil. The refrigerant
enters the suction line and returns to the compressor
When humidity is called for, Solenoid H-11 SOL is de-energized.
For Dry Bulb Temperature cooling in humidity mode, 1-SOL is energized. This allows refrigerant to • ow
through the R-404A T.E.V. into the evaporator, which cools the chamber. When 1-SOL is off, 4-SOL is
energized allowing refrigerant hot gas to by-pass back to the suction line.
For Dry Bulb Temperature heating, solenoid 1-SOL is de-energized and 4-SOL is energized, acting a by-pass
for the refrigeration circuit. The heaters are activated to warm the chamber.
To Next Page
Loading...