29
Occupied Setpoint (
Setpoints
RH.SP
) during the occupied
period and Space RH Unoccupied Setpoint (
Set-
points
RH.UN
) during unoccupied periods. If the Space
Humidity Sensor (
SP.RH
) value is above the Space RH Set-
point (
RH.SP
), then dehumidification is needed. If the
Space Humidity Sensor (SP.RH) value is below the Space
RH Setpoint (
RH.SP
) minus the Space RH Deadband (
Set-
points
RH.DB
), then dehumidification is no longer need-
ed. If the unit is configured for space sensor control (
Con-
figuration
UNIT
U.CTL = 3
), then the setpoint Reheat
Heat SP Deadband (
Setpoints
RH.HB
) applies. This con-
figuration sets the offset above the heating set point at
which a unit in Reheat2 mode will turn off. This is a protec-
tion against over cooling the space and causing a heat de-
mand.
NOTE: When there is a dehumidification demand, the economizer
damper position is limited to its minimum damper position (
Oper-
ating Mode
ECON
EC.MP
).
REHEAT MODES
Dehumidification (reheat) is a cooling mode function. Refer to
Cooling Operation for cooling mode control. With Humidi-MiZer
units there are three additional HVAC Mode (HVAC) expanded
texts available for the user: Reheat1, Reheat2, and Reheat1/Re-
heat2. Selection of the reheat mode for each refrigerant circuit is
determined by the dehumidification demand and the cooling de-
mand. Table 10 shows the corresponding circuit mode and output
status for the different demand combinations. Units with multiple
circuits can operate with a combination of Reheat1 and Reheat2
circuits, as determined by the amount of space cooling demand.
See Appendix B for complete tables of unit operation response to
thermostat and humidity inputs.
NOTE: Compressor staging control for Humidi-MiZer units re-
quires that circuit A always operates when circuit B is on. This ap-
plies to normal operation, service test, and for control alarm re-
sponses. This operation difference is required due to the fact that
the Motormaster outdoor fan control senses circuit A only.
Operation of the revised refrigerant circuit for each mode is de-
scribed below.
NOTE: x = refrigerant circuit A or B
Normal Cooling
For 48/50HC04-12 units, refrigerant flows from the outdoor con-
denser through the normally open Cooling Liquid Valve (
CLV.x
)
to the expansion device. Reheat Liquid Valve (
RLV.x
) and Reheat
Discharge Valve (
RDV.x
) are closed. (See Fig. 9.) For 48/
50HC14-28 units, refrigerant flows from the outdoor condenser
through the de-energized 3-way Liquid Diverter Valve (
LDV.x
) to
the expansion device. Reheat Discharge Valve (
RDV.x
) is closed.
Reheat 1 (Subcooling Mode)
This mode increases latent cooling and decreases sensible cooling
compared to normal cooling.
For 48/50HC04-12 units, refrigerant flows from the outdoor con-
denser, through the normally open Reheat Liquid Valve (
RLV.x
),
and through the reheat condenser coil to the expansion device.
Cooling Liquid Valve (
CLV.x
) and Reheat Discharge Valve
(
RDV.x
) are closed. (See Fig. 11.)
For 48/50HC14-28 units, refrigerant flows from the outdoor con-
denser, through the energized 3-way Liquid Diverter Valve
(
LDV.x
), and through the reheat condenser coil to the expansion
device. Reheat Discharge Valve (
RDV.x
) is closed. (See Fig. 12.)
Reheat 2 (Hot Gas ReheatMode)
This mode provides maximum latent cooling with little to no sen-
sible capacity. This mode can operate to provide dehumidification
when there is no cooling demand. Similar to Reheat 1 mode, re-
frigerant flows from the outdoor condenser, through the normally
open Reheat Liquid Valve (
RLV1.x
), or through the energized 3-
way Liquid Diverter Valve (
LDV.x
), and through the reheat con-
denser coil to the expansion device. Reheat Discharge Valve
(
RDV.x
) is open which provides some compressor discharge gas
to the reheat condenser to further increase the reheat of the evapo-
rator air stream (See Fig. 13 or 14 based on unit and size).
Table 10 — Control Modes with Humidi-MiZer System
Output and Valve States versus Circuit Mode .x = Circuit A or B identifier
DEMAND AND MODE
OUTPUTS
48/50HC 04-12 VALVES
48/50HC 14-28 VALVES
Space
Humidity
Circuit
Cooling
Demand
Circuit
Mode
Circuit
Compressor
(CMP.x)
Cooling-
Reheat
Control
(CRC)*
Reheat2
Valve
(RH3.x)
CLV.x Valve
2-way
RLV.x Valve
2-way
RDV.x
Valve 2-way
RLV.x Valve
3-way
RDV.x
Valve 2-way
—
—
No power
Off
Off
Off
Off (open)
Off (open) Off
(closed) Off Off
(closed)
Low
No Off Off Off
Off
Off
(open)
On
(closed) Off (closed) Off Off
(closed)
Low
Yes
Cool
On
Off
Off
Off (open) On (closed) Off (closed) Off Off
(closed)
High
Yes Reheat1 On
On
Off
On
(closed)
Off
(open)
Off
(closed) On Off
(closed)
High
No
Reheat2
On
On
On
On (closed) Off (open)
On (open)
On
On (open)
Summary of Contents for /50HC 04-28
Page 69: ...69 Fig 24 Typical Control Diagram for 48HC 04 14 Units 48HC 08 09 shown ...
Page 70: ...70 Fig 25 Typical Power Diagram for 48HC 04 14 Units 48HC 08 09 shown ...
Page 71: ...71 Fig 26 Typical Control Diagram for 50HC 04 14 Units 50HC 14 shown ...
Page 72: ...72 Fig 27 Typical Power Diagram for 50HC 04 14 Units 50HC 14 Non Humidi MiZer shown ...
Page 73: ...73 Fig 28 Typical Control Diagram 48HC 17 28 Units ...
Page 74: ...74 Fig 29 Typical Control Diagram 50HC 17 28 Units ...
Page 75: ...75 Fig 30 Typical Humid MiZer Power Diagram and Component Arrangement 48 50HC 17 28 Units ...
Page 76: ...76 Fig 31 Typical Non Humid MiZer Power Diagram and Component Arrangement 48 50HC 17 28 Units ...
Page 89: ...89 Fig 42 Modulating ERV Wiring Schematic ...
Page 90: ...90 Fig 43 EnergyX ERV Control Box Component Layouts ...
Page 101: ...101 Fig 59 Exhaust Fan Assembly Removal Exhaust Fan Assembly ...
Page 141: ......