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15
PC Program Instructions
6 Parameters (continued)
Tank differential temp
This parameter determines how far below the tank setpoint
the tank sensor temperature must go to start a HW call for
heat. This setting can be adjusted by accessing parameter 4AT.
The temperature range is 0°F (0°C) to 100°F (38°C). The
default value is 5°F (3.5°C).
Time to switch between HW and SH (SH/HW sw tim)
This feature sets the length of time the control will stay in HW
mode when a SH call has been received. After this time period
has expired the control will determine if a SH call needs to be
serviced. If the System Supply Temperature is below the
turn-on temperature, the control will revert to SH mode.
Otherwise, it will remain in HW mode until the System
Supply Temperature drops below the turn-on temperature. If
a HW call is still active the timer will reset. After the time
period has expired the control will revert to HW mode. This
will continue back and forth until one of the demands has
been satisfied. This parameter can be changed by accessing
parameter 4AU. The time range of this parameter is 10
minutes to 240 minutes. The default value is 30 minutes.
Boost function time (Boost Tim)
This function will only work if the outdoor air sensor is
connected. The Boost Function Time sets the amount of time
that must elapse during an SH demand before the water
temperature setpoint will be increased. This parameter can be
changed by accessing parameter 4AV. The time range for this
parameter is 1 minute to 60 minutes. The default value is 20
minutes.
Boost function temp increase (Boost incr)
This function will only work if the outdoor air sensor is
connected. If a SH demand lasts longer than the programmed
time setting in parameter 4AV, and there have been no HW
demands, the control will increase the water temperature
setpoint by the amount in this parameter. If the SH demand
continues through another time period, the setpoint will be
increased again. This will continue until either the SH
demand ends, a maximum of 20 increases has occurred, or the
maximum user setpoint has been reached. Once the SH
demand has been satisfied the setpoint will revert back to its
calculated setting. The boost temperature can be changed by
accessing parameter 4AW. The temperature range of this
parameter is 0°F to 45°F(25°C). The default value is 0°. This
feature will be active if this parameter is set to anything other
than 0°F.
Outlet setpoint temp for indirect HW (Indir HW Setp)
When a HW call for heat becomes active, the control will
control the firing rate of the boiler in order to maintain the
outlet water temperature at this setpoint. This parameter can
be changed by accessing parameter 4AX. The temperature
range of this parameter is 50°F (10°C) to 190°F (88°C). The
default value is 180°F (82°C).
Cascade max SH step power based (Max outl temp)
When a system supply sensor is connected, each burner applies
this setpoint to its outlet sensor during a space heating call for
heat. The controls limit the modulation of each burner in order
to maintain the system supply temperature at the setpoint. If an
outlet temperature approaches this setting, the controls will also
limit the modulation of that burner in order to not exceed the
setting. The control uses parameters 4AD and 4AE to turn the
burner off and back on based on this setting as well. This
parameter can be changed by accessing parameter 4AY. The
temperature range of this parameter is 32°F (0°C) to 212°F
(100°C). The default value is 185°F (85°C).
Cascade DHW setpoint offset for all members
Not used.
On the tabs at the top of the window (FIG. 6-7), click on the tab
labeled 4C Boiler Config to set the parameters that enable BMS
operation and determine the controlling sensor (see FIG. 6-7
below).
Figure 6-7 Parameter Set 4C
Config SH control
The Config SH Control parameter selects the method used to
control the modulation of the boiler. This parameter must
always be set to 2.
BMS
If BMS control of Cascade has been selected in parameter 4CG,
the control must know how to use the 0-10Vdc signal. This can
be either temperature based or power based. This parameter can
be changed by accessing parameter 4CB. The allowable values
for this parameter are “0” for power or “2” for temperature. The
default value is 0.