Laars Pennant PNCH Installation And Operation Instructions Manual - page 44
LAARS Heating Systems
Page 44
Figure 30. Temperature Control Outdoor Start Graph.
pump operation is continuous. Also, during outdoor
reset, with the pump delay set to
ON
, the pump
continues to run even during Warm Weather Shut
Down.
6.4.7 Setpoint Operation
When either mode 1 or 2 is selected, the control
controls the water temperature based on a fixed
setpoint. The setpoint temperature is set using the BOIL
BOIL
BOIL
BOIL
BOIL
TARGET
TARGET
TARGET
TARGET
TARGET item in the ADJUST
ADJUST
ADJUST
ADJUST
ADJUST menu.
Heat Demand – For “heat demand” to exist,
there must be continuity between the Com D (common
demand) and the Ht D (heat demand) terminals. The
Pennant ships with a jumper between these terminals.
The control also evaluates the sensor(s) installed
in the system, including the outlet sensor provided on
the boiler when using mode 1. When the control senses
continuity between Com D and Ht D terminals, and
that the sensor reading is below the target temperature,
the control will activate the Dem segment in the
display.
The control energizes the pump (on pump
mounted boilers) and energizes the Pmp Pmp
terminals. The boiler pump segment is turned on in the
display. The control then operates the stages to
maintain the setpoint temperature.
6.4.8 Dedicated Domestic Hot Water
When mode 3 is selected, the control provides
dedicated domestic hot water operation.
Internal DHW Demand – A sensor is required
to be connected on the SC2 and Sup/S terminals. An
internal demand for DHW is generated when the
temperature demand for DHW sensor drops ½ of the
tank differential setting below the desired DHW tank
temperature. The TANK TARGET
TANK TARGET
TANK TARGET
TANK TARGET
TANK TARGET setting is used to set
the desired DHW tank temperature.
Once an internal demand is generated, the Dem
segment turns on in the LCD. The control then closes
the Pmp Pmp contact, which starts the pump and the
control turns on the boiler pump segment in the
display. The control then operates the stages to
maintain the programmed boiler target temperature at
the boiler outlet sensor.
The boiler target temperature is set using the
BOIL TARGET
BOIL TARGET
BOIL TARGET
BOIL TARGET
BOIL TARGET item in the Adjust
Adjust
Adjust
Adjust
Adjust menu. NOTE:
External demand is not required in this mode of
operation.
Tank Differential – A differential setting that
operates ½ above and below the TANK TARGET
TANK TARGET
TANK TARGET
TANK TARGET
TANK TARGET is
selectable using the TANK DIFF
TANK DIFF
TANK DIFF
TANK DIFF
TANK DIFF item in the Adjust
Adjust
Adjust
Adjust
Adjust
menu.
6.4.9 Outdoor Reset Operation
When either mode 4 or 5 is selected, the control
uses outdoor reset to control the water temperature.
Outdoor reset adjusts the target temperature based on
the outdoor air temperature and reset ratio. The reset
ratio is determined from the Boiler Start, Boiler
Design, Outdoor Start and Outdoor Design settings.
Heat Demand – For “heat demand” to exist,
there must be continuity between the Com D (common
demand) and the Ht D (heat demand) terminals. The
Pennant ships with a jumper between these terminals.
The control also evaluates the sensor(s) installed
in the system. If the control is not in warm weather
shutdown (WWSD), and the sensor(s) are below the
target temperature, the Dem segment is turned on in
the display. The control energizes the pump (on pump
mounted boilers) and energizes the Pmp-Pmp
terminals, and the boiler pump segment is turned on in
the display. The control then operates the stages to
maintain the setpoint temperature.
Boiler Start (BOIL START
BOIL START
BOIL START
BOIL START
BOIL START) – The BOIL START
temperature is the theoretical boiler supply water
temperature that the heating system requires when the
outdoor air temperature equals the OUTDR START
temperature setting. The BOIL START is typically set
to the desired building temperature (see Figure 30).
Outdoor Start (OUTDR START
OUTDR START
OUTDR START
OUTDR START
OUTDR START) – The OUTDR
START temperature is the outdoor air temperature at
which the control provides the BOIL START water
temperature to the system. The OUTDR START is
typically set to the desired building temperature.
Outdoor Design (OUTDR DSGN
OUTDR DSGN
OUTDR DSGN
OUTDR DSGN
OUTDR DSGN) – The OUTDR
DSGN is the outdoor air temperature that is the
typical coldest temperature of the year where the
building is located. This temperature is used when
doing heat loss calculations for the building.
Boiler Design (BOIL DSGN
BOIL DSGN
BOIL DSGN
BOIL DSGN
BOIL DSGN) – The BOIL DSGN
temperature is the water temperature required to heat