22
HEATING MODE CONTROL
The heating HVAC mode (
Run Status
MODE
HVAC=4
),
represents both types of heating (gas or electric) under all types of
control. For the unit to be allowed to enter the heat mode, heat
must be enabled (
HT.TY = 1 or 2
), and the Outdoor Air Tempera-
ture (
Temperatures
AIR.T
OAT
) must be less than the Heat-
ing Lockout Temp (
Configuration
HEAT
HT.LO
). Heat OAT
Lockout (
Run Status
MODE
H.LOC
) displays when heat is
locked out on outdoor temperature and therefore can not allow
heat mode. The control will display if it is ok to select the heating
mode (
Operating Modes
HEAT
OK.HT = Yes
).
Thermostat Control
For the unit to enter heating mode, three additional things must
be true: the indoor fan must be ok to use, the mode changeover
time guard must be expired, and there must be a heating de-
mand (W1, W2). The unit will remain in heating until the heat-
ing demand is dropped or if any of the above conditions turn
false. The heating mode can not officially end until all heat
stages are off and the IGC fan request is dropped (on gas units).
Space Sensor Control
For the unit to enter heating mode, five additional things must
be true: the indoor fan must be ok to use, the mode changeover
time guard must be expired, the unit must have a valid space
temperature, the W1 jumper must be installed, and there must
be a heating demand. The unit will remain in heating for at
least one minute and until the heat demand drops below –0.5°F
or if any of the above conditions turn false. The heating mode
can not officially end until all heat stages are off and the IGC
fan request is dropped (on gas units without Humidi-MiZer
system).
SUPPLY-AIR TEMPERATURE SENSOR (SAT)
The SAT Heat Mode Sensing (
Configura-
tion
HEAT
SAT
SAT.H
) informs the unit if the supply air
sensor has been relocated downstream of the heat section. This
configuration affects the Supply Air Temperature (
Tempera-
tures
AIR.T
SAT
) value displayed as listed below.
When
SAT.H = DSBL
, the Supply Air Temperature (
Tempera-
tures
AIR.T
SAT
) value on the scrolling marquee and the
CCN tables will be forced to zero when heat outputs turn ON
or OFF and for 5 minutes after. The default Supply Air Tem-
perature location is at the fan inlet, upstream of the heat sec-
tion.
When
SAT.H = ENBL
, the Supply Air Temperature (
Tempera-
tures
AIR.T
SAT
) sensor reading is displayed at the scroll-
ing marquee and the CCN tables during heating mode. This
setting should only be used if the original SAT sensor wires are
removed from the Main Base Board (MBB) and replaced by an
accessory SAT sensor located in the supply duct downstream
of the heat section.
There are two supply air temperature limits that affect heating
operation, the Maximum SAT Lower Level (
Configura-
tion
HEAT
SAT
SAM.L
) the Maximum SAT Upper Lev-
el (
Configuration
HEAT
SAT
SAM.U
). Any time the
supply air temperature rises above SAM.L the heat staging will
be limited to what is currently on and no additional stages can
be added until the supply air temperature falls back below
SAM.L
. If the supply air temperature rises above
SAM.U
, then
heating will be reduced by removing a heat stage. That stage
can not be added again until the Supply Air Temperature falls
below
SAM.L
. If the supply air temperature stays above
SAM.U
, then another stage will be removed after the Heat
Stage Decrease Time (
Configuration
HEAT
H.DEC
). If
SAM.L
and
SAM.U
are configured so that they are close to-
gether, the last stage of heat might cycle rapidly, slowed only
by its minimum on and off-time requirements.
STAGING CONTROL
Once the unit is in a heating mode, it must decide what the de-
mand is and how to satisfy. Based on the unit control configura-
tion, requested heating stages (
Run Status
HEAT
REQ.H
)
will be determined then passed to heat control to actually add the
heating stages.
Thermostat Control
There are two ways of requesting stages when thermostat con-
trol is enabled: Traditional Thermostat control or Adaptive
control. Traditional Thermostat control is used if the Thermo-
stat Control Type (
T.CTL
) is set to 1, 2, or 3. Adaptive control
is used if Thermostat Control (
T.CTL
) is set for 0.
T.CTL = 0
(Adaptive Control)
Stage timers and supply air temperature limits apply when de-
termining the request for stages. The first request (
REQ.C=1
)
comes immediately when the W1 input is active. The Heat
Stage Increase Time (
Configuration
HEAT
H.INC
) or the
Heat Stage Decrease Time (
Configuration
HEAT
H.DEC
)
has to expire before another stage can be added or a stage can
be subtracted. If at any time the Supply-Air Temperature (SAT)
rises above the Maximum Supply Air Temperature Lower Lev-
el (
Configuration
HEAT
SAT
SAM.L
), the requested
stages will not be allowed to increase. If at any time the SAT
rises above the Maximum Supply Air Temperature Upper Lev-
el (
Configuration
HEAT
SAT
SAM.U
), the requested
stages will be reduced by one without honoring
H.DEC
.
T.CTL = 1, 2 or 3
(Traditional Thermostat Control)
Stage timers and supply air temperature limits do not apply
when determining the request for stages. Request staging will
follow the thermostat inputs directly. W1 will request one
stage. W2 will request all stages.
Space Sensor Control
Space sensor staging control is an adaptive anticipation control
that weighs the actual space demand against the trend of that
demand. It also honors stage time guards and supply air limits.
The demand for heating in the space is displayed as the Heat-
ing Demand (
Run Status
HEAT
DMD.H
). The control
tries to anticipate the change in the space because of its current
stage status. This anticipation is based on the Heat Demand
Trend (
Operating Modes
HEAT
TRD.H
). This trend will
show the control how the space is reacting to the current run-
ning conditions and help it decide when to add or remove one
stage from the requested stages. The Heat Stage Increase Time
(
Configuration
HEAT
H.INC
) or the Heat Stage Decrease
Time (
Configuration
HEAT
H.DEC
) has to expire before
another stage can be added or a stage can be subtracted. If at
any time the Supply-Air Temperature (SAT) rises above the
Maximum Supply Air Temperature Lower Level (
Configura-
tion
HEAT
SAT
SAM.L
), the requested stages will not be
allowed to increase. If at any time the SAT rises above the
Maximum Supply Air Temperature Upper Level (
Configura-
tion
HEAT
SAT
SAM.U
), the requested stages will be re-
duced by one without honoring
H.DEC
.
HEAT RELAY CONTROL
The heat relay control is responsible for energizing or de-energiz-
ing the MBB’s heat stage relays and works hand in hand with the
staging control. As the staging control requests stages, the heat
relay control determines what actual heat relays are available or
energized and tries to provide stages for what is requested. The
availability of a heat relays depends on heat being installed, how
many stages, and time guards. The type of Heat Installed (
Con-
figuration
HEAT
HT.TY
) must be set for gas or electric for
any stages to be available. The Number of Heat Stages (
Configu-
ration
HEAT
N.HTR
) configuration tells the control how
many heat relays can be used. Heat Stage 1 Timeguard (
Run Sta-
tus
HEAT
TG.H1
) and Heat Stage 2 Timeguard (
Run Sta-
tus
HEAT
TG.H2
) display the time a respective heat relay
has before it is available for use. The available stages at any given
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: ......