LAARS Pennant PNCV (Sizes 500-2000) - Install and Operating Manual - Manual (Page 42)

LAARS Heating Systems Page 42
Figure 28. Temperature Control Interstage Differential.
6.4 Advanced Topics
For most installations, Section 6.3 provides all
the information required to set up the Pennant boiler,
and this section should be skipped. Continue setup in
Section 6.5.
This section provides definitions of the pro-
gramming parameters, advanced programming topics,
and other information that may be of interest.
Advanced programming mode allows the
installer to set the temperature control for proportional
staging. In advanced programming mode, the
interstage differential, interstage delay, interstage on
and off delay, and minimum time on and off are all set
manually.
NOTE: Advanced programming mode is not required
in most applications, and is intended for advanced
installers only.
To enter advanced programming mode, remove
the bezel on the temperature control by pulling out at
the bottom. Remove the small phillips head screw to
access the dip switch. The dip switch is mounted on
a circuit board. Locate the letter “A” on the circuit
board and slide the corresponding dip switch toward
the letter “A”. The default setting of this dip switch is
toward the OFF lettering on the circuit board.
6.4.1 Differential
Differential has an abbreviated name of DIFF. An
on/off heat source must be operated with a differential
in order to prevent short cycling. The differential
is divided around the boiler target temperature (see
Figure 28 ). The first stage contact will close when the
water temperature at the operating sensor is one-half of
the differential setting below the target temperature. It
will open when the water temperature at the operating
sensor is one-half of the differential setting above the
target temperature. The remaining stages will operate
sequentially, based on the staging mode selected.
6.4.2 Staging Mode
The Pennant 500 and 750 control operates two
stages. The Pennant 1000 control operates three stages.
The Pennant control for models 1250–2000 operates
four stages. The method of staging used by the
control is either P (proportional) or PID (proportional
& integral & derivative), and is selected using the
STGMODE item in the ADJUST menu.
Proportional (P) – Proportional staging, also
known as step staging, is based on manually adjusted
settings which determine when the next stage is
required to turn on. These manual settings are based
on temperature and time. The interstage differential
sets the temperature drop at which the next stage turns
on. However, in order for a stage to fire, the interstage
delay on and minimum off times must first elapse.
Interstage Differential (STG DIFF) – The
interstage differential is the temperature drop at which
the next stage will turn on. Once a stage turns on, the
next stage cannot turn on until the temperature drops
the interstage differential below the temperature at
which the previous stage turned on. The interstage
differential is adjustable through the STG DIFF
setting in the Adjust menu (see Figure 28 ).
Interstage Delay On (ON DLY) – The interstage
delay on is the amount of time that must elapse before
turning on the next stage. Once a stage turns on, the
next stage cannot turn on until the interstage delay
on time elapses. The interstage delay on is adjustable
through the ON DLY setting in the Adjust menu.
Interstage Delay Off (OFF DLY) – The
interstage delay off is the amount of time that must
elapse before turning off the next stage. Once a stage
turns off, the next stage cannot turn off until the
interstage delay off time elapses. The interstage delay
off is adjustable through the OFF DLY setting in the
Adjust menu.
Minimum On Time (MIN ON) – The minimum
on time is the minimum amount time that a stage must
be on before it is allowed to turn off. Once a stage
turns on, it cannot turn off until a minimum on time
elapses. The minimum on time is adjustable through
the MIN ON setting in the Adjust menu.
Minimum Off Time (MIN OFF) – The
minimum off time is the minimum amount time that a
stage must be off before it is allowed to turn on. Once
a stage turns off, it cannot turn on until a minimum
off time elapses. The minimum off time is adjustable
through the MIN OFF setting in the Adjust menu.
Proportional & Integral & Derivative (PID)
– PID staging allows the control to determine when
the next stage is required to turn on. The control
automatically determines the settings that are manually
selected in proportional staging mode. After each stage
is turned on in the firing sequence, the control waits a
minimum amount of time before turning on the next