72
evaporator leaving air temperature. The liquid refrigerant then
enters a thermostatic expansion valve (TXV) where the refrig-
erant pressure is decreased. The refrigerant enters the TXV and
evaporator coil at a temperature lower than in standard cooling
operation. This lower temperature increases the latent capacity
of the evaporator. The refrigerant passes through the evaporator
and is turned into a superheated vapor. The air passing over the
evaporator coil will become colder than during normal opera-
tion. However, as this same air passes over the Humidi-MiZer
reheat coil, it will be warmed to meet the supply air setpoint
temperature requirement. See Fig. 18.
Temperature Compensated Start —
This logic is
used when the unit is in the unoccupied state. The control will
calculate early Start Bias time based on Space Temperature
deviation from the occupied cooling and heating setpoints.
This will allow the control to start the unit so that the space is at
conditioned levels when the occupied period starts. This is
required for ASHRAE (American Society of Heating,
Refrigerating, and Air-Conditioning Engineers) 90.1 compli-
ance. A space sensor is required for non-linkage applications.
SETTING UP THE SYSTEM — The settings for tempera-
ture compensated start can be found in the local display under
Configuration
UNIT
.
TCST-Cool Factor (
TCS.C
) — This is the factor for the start
time bias equation for cooling.
TCST-Heat Factor (
TCS.H
) — This is the factor for the start
time bias equation for heating.
NOTE: Temperature compensated start is disabled when these
factors are set to 0.
ITEM
EXPANSION
RANGE UNITS CCN POINT
TCS.C
Temp.Cmp.Strt.Cool Factr 0 - 60
min
TCSTCOOL
TCS.H
Temp.Cmp.Strt.Heat Factr 0 - 60
min
TCSTHEAT
Evaporator Discharge Temperature
In Subcool or Reheat Mode, compressor staging
and increased subcooling drives evaporator
discharge temperature down to meet higher latent
loads
Airflow
EVAPORATOR
HUMIDI-MIZER ADAPTIVE
DEHUMIDIFICATION
SYSTEM COIL
Supply Air Temperature Control
Innovative algorithm to control supply air temperature
modulates flow bypass to meet desired supply air setpoint -
no overcooling or overheating of the space.
Subcooling Mode: Meet Cooling Mode Supply Air Setpoint
Reheat Mode: Meet Return Air Offset or Reheat Setpoint (configurable)
CCT
S
AT
D.C.SP COOL
RAT-D.V.RA or
D.V.HT
Fig. 17 — Humidi-MiZer
®
System Control
3
4
EXPANSION
INDOOR AIR
EVAPORATOR
5
5'
EVAPORATOR
REHEAT HX
EXPANSION
DEVICE
4'
3'
CHECK VALVE
3-WAY VALVE
3a'
2'
2a'
BYPASS
MODULATING
VALVE
CONDENSER
OUTDOOR AIR
CONDENSER
MODULATING
VALVE
1'
COMPRESSOR
1
2
CONDENSER
OUTDOOR AIR
COMPRESSOR
CIRCUIT B
CIRCUIT A
Fig. 18 — Humidi-MiZer
®
System Diagram
Summary of Contents for Carrier Weathermaker 48A2
Page 105: ...105 Fig 20 Typical Main Control Box Wiring Schematic 48 50A2 A3 A4 A5 Units...
Page 106: ...106 Fig 21 Typical Auxiliary Control Box Wiring Schematic...
Page 107: ...107 Fig 22 Typical 2 Stage Gas Heat Wiring Schematic Size 060 Units Shown a48 8357...
Page 108: ...108 TO NEXT PAGE Fig 23 Typical Staged Gas Heat Wiring Schematic Size 060 Units Shown A48 7296...
Page 109: ...109 Fig 23 Typical Staged Gas Heat Wiring Schematic Size 060 Units Shown cont A48 8358...
Page 110: ...110 Fig 24 Typical Electric Heat Control Schematic 50 Series Size 060 Units Shown a50 8228...
Page 111: ...111 Fig 25 Typical Power Schematic 48 50A2 A3 A4 A5 060 Unit Shown...
Page 112: ...112 Fig 26 Typical Low Ambient Controls Option Wiring...
Page 113: ...113 Fig 27 Typical Small Chassis Component Location Size 020 035 Units...
Page 114: ...114 Fig 28 Typical Large Chassis Component Locations Size 040 060 Units...
Page 118: ...118 Fig 30 Economizer Control Board ECB1 and VAV Control Board ECB2 A48 7706...
Page 142: ...142 A48 3733 Fig 56 Main Burner Removal...
Page 176: ...176 APPENDIX C VFD INFORMATION cont Fig F Internal Enclosure Fan Replacement A48 7716...
