LAARS Pennant PNCV (Sizes 500-2000) - Install and Operating Manual User Manual
Page 44
LAARS Heating Systems
Page 44
Figure 30. Temperature Control Outdoor Start Graph.
selected, 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 TARGET item in the 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 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 item in the 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 is
selectable using the
TANK DIFF item in the 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) – 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) – 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) – 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) – The BOIL