33
REHEAT CONTROL
The cooling staging and compressor control routines are re-
sponsible for controlling each circuit in one of the three sub-
modes (Cool, Reheat1, or Reheat2). When there is only a cool-
ing demand, one or more circuits will operate in normal cool-
ing mode. When there is only dehumidification demand, all
circuits will operate in Reheat2 mode. When there is both cool-
ing demand and dehumidification demand, all circuits will op-
erate in either Reheat1 or Reheat2 mode, with the portion of
Reheat1 circuits determined from the cooling demand. The Re-
quested Reheat2 Stages (
Operating Modes
COOL
HMZR
REQ.R
) shows the control’s request for reheat cir-
cuits if cooling is not already requesting all stages. Available
Reheat2 Stages (
Operating Modes
COOL
HMZR
AVL.R
) displays circuits that are available for reheat use. Actu-
al Reheat2 Stages (
Operating Modes
COOL
HMZR
ACT.R
) displays the current number of circuits running in Re-
heat2 mode. These three status points should only be moni-
tored when there is only a dehumidification demand, because
their values can be forfeited to cooling stages when cooling de-
mand is present. Reheat2 Stage Incr. Time (
Configura-
tion
HMZR
R.INC
) and Reheat2 Stage Decr. Time (
Con-
figuration
HMZR
R.DEC
) set the time delay when adding
or subtracting a compressor for a reheat function. These only
apply when using adaptive thermostat or space sensor control.
There are three relay outputs that show reheat status. Cool Re-
heat1 Control (
Outputs
COOL
CRC
) shows when the unit
has switch from pure cooling to reheat ready (based on a dehu-
midification demand). Reheat2 Valve A (
Out-
puts
COOL
RH2.A
) and Reheat2 Valve B (
Out-
puts
COOL
RH2.B
) display when the respective circuit’s
Reheat2 valve is energized.
A circuit can be restricted from Reheat2 operation by the out-
side temperature and saturated suction temperature. Reheat2
OAT Limit A (
Configuration
HMZR
RA.LO
) and Reheat2
OAT Limit B (
Configuration
HMZR
RB.LO
) set the low-
est outside temperature the respected circuit is allowed to run
in reheat2 mode. The lockout on/off status is shown as Reheat2
OAT Lockout A (
Operating Modes
COOL
HMZR
R.LO.A
) and Reheat2 OAT Lockout B (
Operating
Modes
COOL
HMZR
R.LO.B
) for their respective cir-
cuit. If a circuit’s saturated suction pressure falls below the low
limit configuration during Reheat2 operation, the circuit will
switch to reheat1 (the circuits Reheat2 valve will be turned off)
for at least 2 minutes and until its suction rises back above the
high limit. Reheat2 SSP Lo Limit A (
Configura-
tion
HMZR
RA.LP
) and Reheat2 SSP Lo Limit B (
Config-
uration
HMZR
RB.LP
) set the low pressure limit for Re-
heat2 mode for individual circuits. Reheat2 SSP Hi Limit A
(
Configuration
HMZR
RA.HP
) and Reheat2 SSP Hi Limit
B (
Configuration
HMZR
RB.HP
) set the high pressure
limit for Reheat2 mode for each circuit.
REHEAT MODE DIAGNOSTIC HELP
The status of reheat mode sensor inputs may be viewed within
the display Inputs menu. The status of reheat mode outputs
may be viewed within the display Outputs or
Run Sta-
tus
COOL
menus. Additional diagnostic help, including sta-
tus of circuit reheat temperature limit lockouts may be viewed
within the Humidi-MiZer sub-menu of the cooling mode diag-
nostic table at
Operating Modes
COOL
HMZR
.
The Service Test mode may be used to force the system to op-
erate in various stages of Reheat1 or Reheat2 mode, or to inde-
pendently operate the reheat valve control outputs.
The following forced operating states are changed or added to
the available service test operation for a Humidi-MiZer
equipped unit:
Service Test
COOL
CMP.A (Cool A Test)
A value of On will turn on circuit A in Normal Cooling mode.
Service Test
COOL
CMP.B (Cool B Test)
A value of On will turn on circuits A and B in Normal Cooling
mode.
Service Test
HMZR
RH1.A (Reheat1 A Test)
A value of On will turn on circuit A in Reheat1 mode.
Service Test
HMZR
RH1.B (Reheat1 B Test)
A value of On will turn on circuits A and B in Reheat1 mode.
Service Test
HMZR
RH2.A (Reheat2 A Test)
A value of On will turn on circuit A in Reheat2 mode.
Service Test
HMZR
RH2.B (Reheat2 B Test)
A value of On will turn on circuits A and B in Reheat2 mode.
Service Test
HMZR
CRC (Cool-Reheat1 Valve Test)
For 48/50HC04-12 units, a value of On will turn on the CRC
relay. This will turn on
CLV.x
valves and turn off
RLV.x
valves.
For 48/50HC14-28 units, a value of On will turn on the CRC
relay. This will energize the
LDV.x
valves.
Service Test
HMZR
RHV.A (Reheat2 Valve A Test)
A value of On will turn on the
RDV.A
valve.
Service Test
HMZR
RHV.B (Reheat2 Valve B Test)
A value of On will turn on the
RDV.B
valve.
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
set points. 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 90.1 compliance. A space
sensor is required for non-linkage applications.
SETTING UP THE SYSTEM
The settings for temperature compensated start can be found in
the local display under
Configuration
UNIT
.
Temp Comp Strt Cool Factr (TCS.C)
This is the factor for the start time bias equation for cooling.
Temp Comp Strt Heat Factr (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.
TEMPERATURE COMPENSATED START LOGIC
The following conditions must be met for the algorithm to run:
• Unit is in unoccupied state.
• Next occupied time is valid.
• Current time of day is valid.
• Valid space temperature reading is available (sensor or
CCN network).
The algorithm will calculate a Start Bias time in minutes using
the following equations:
If (space temperature > occupied cooling set point)
Start Bias Time = (space temperature – occupied cooling set
point)*
TCS.C
If (space temperature < occupied heating set point)
Start Bias Time = (occupied heating set point – space tempera-
ture)*
TCS.H
When the Start Bias Time is greater than zero the algorithm
will subtract it from the next occupied time to calculate the
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
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: ......