Humidi- - Mizer Adaptive Dehumidification System - Carrier 48HC D17 Series Service And Maintenance Instructions

5/8" HEX
EXAMPLE:
Model 48HC*D28
Circuit A (from Fig. 14):
Outdoor Temperature . . . . . . . . . . . . . . . . . .
Suction Pressure . . . . . . . . . . . . . . . . .
Suction Temperature should be
Circuit B (from Fig. 15):
Outdoor Temperature . . . . . . . . . . . . . . . . . .
Suction Pressure . . . . . . . . . . . . . . . . .
Suction Temperature should be
HUMIDI- -MIZER
DEHUMIDIFICATION SYSTEM
Units with the factory- - equipped Humidi- - MiZer
are capable of providing multiple modes of improved
dehumidification as a variation of the normal cooling
cycle. The design of the Humidi- - MiZer system allows for
two humidity control modes of operation of the rooftop
unit, utilizing a common
dehumidification coil located downstream of the standard
evaporator coil. This allows the rooftop unit to operate in
both a dehumidification (Subcooling) mode and a hot gas
Reheat Mode for maximum system flexibility.
Humidi- - MiZer package is factory- - installed and will
operate whenever there is a dehumidification requirement
present.
The Humidi- - MiZer system is initiated based on an input
from a discrete input from a mechanical space or return
air humidistat.
Humidi- -MiZer Modes
Dehumidification Mode (Subcooling)
This mode will be engaged to satisfy part- - load type
conditions when there is a space call for cooling and
dehumidification. Although the temperature could have
dropped, decreasing levels of the sensible load in the
space, the outdoor and/or space humidity levels can be
higher. A typical scenario could be when the outside air is
85_F (29_C) with 70% to 80% relative humidity (RH).
SEAT
1/2-20
UNF RH
0.596
o
30
0.47
This surface provides a metal to metal seal when
torqued into the seat. Appropriate handing is
required to not scratch or dent the surface.
Fig. 14 - - CoreMax Access Port Assembly
85_F (29_C)
125 psig (860 kPa)
. . . . . . . . . . 63_F (17_C)
85_F (29_C)
120 psig (830 kPa)
. . . . . . . . . . 58_F (14_C)
ADAPTIVE
®
®
option
subcooling/reheat
The
CORE
(Part No. EC39EZ067)
WASHER
O-RING
1/2" HEX
Desired sensible heat ratio (SHR) for equipment in this
scenario is typically from 0.4 to 0.7. The Humidi- - MiZer
unit will initiate Dehumidification mode when the space
temperature and humidity are both above the temperature
and humidity setpoints and will attempt to meet both
setpoint requirements.
Once the humidity requirement is met, the unit can
continue to operate in normal cooling mode to meet any
remaining sensible capacity load.
sensible load is met and humidity levels remain high the
unit can switch to Hot Gas Reheat mode to provide
neutral, dehumidified air.
Reheat Mode
This mode is used when dehumidification is required
without a need for cooling, such as when the outside air is
at a neutral temperature, but high humidity exists. This
situation requires the equipment to operate at a low SHR
of 0.0 to 0.2. With no cooling requirement calling for
dehumidification,
dehumidification system will turn on both compressors
and open the two hot gas bypass valves allowing
refrigerant flow to the Humidi- - MiZer coil to reheat the
unit's supply air to a neutral temperature.
As the hot bypassed refrigerant liquid (gas or two- - phase
mixture) passes through the Humidi- - MiZer coil, it is
exposed to the to the cold supply airflow coming from the
evaporator coil. The refrigerant is subcooled in this coil to
a temperature approaching the evaporator leaving air
temperature. The liquid refrigerant then enters a
Thermostatic Expansion Valve (TXV) decreasing the air
pressure.
The refrigerant enters the TXV and evaporator coil at a
temperature lower than the temperature in the standard
cooling operation. This lower temperature increases the
latent capacity of the evaporator. The refrigerant passes
through the evaporator turning it into a superheated vapor.
The air passing over the evaporator coil becomes colder
than it would during normal operation. As this same air
passes over the Humidi- - MiZer Reheat Coil, it will be
warmed to the neutral supply air temperature.
12
o
45
DEPRESSOR PER ARI
720 + 0.01/-0.035
FROM FACE OF BODY
7/16-20 UNF RH
Alternatively, if the
the Humidi- - MiZer adaptive
C08453