LAARS Pennant PNCV (Sizes 500-2000) - Install and Operating Manual - Manual (Page 39)

Pennant (500-2000) Page 39
Figure 27. Temperature Control Target Temperature
Graph.
These terminals can power a contactor for a larger
system pump. Laars recommends a minimum pump
delay setting of 5 minutes. See Section 6.4.6 for more
information.
NOTE: In modes other than mode 6, the pump will
run continuously if the “HtD” and “ComD” terminals
are jumpered and not connected to a zone valve or
pump end switch, or other “contact closure” device
to indicate when the heat demand in the system is
satisfied. The pump will never run, and the boiler will
never fire, if the jumper is removed and the terminals
left empty.
OUTDOOR RESET (modes 4 and 5): 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 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 both “PMP” terminals.
The pump symbol appears in the display (see Figures
25 and 26). The control then operates the stages to
maintain the setpoint temperature.
Boil Start (Boiler Start): The BOIL START
temperature is the theoretical boiler supply
temperature that the heating system requires when the
outdoor air temperature equals the OUTDR START
temperature setting.
EXAMPLE 1
DHW (Mode 3) Programming. For domestic
hot water systems up to 175°F / 79°C, use mode 3 as
described below.
Step 1: Install the additional sensor into the
storage tank, wiring it to “SC2” and “SUPS” terminals
on the field wiring panel ( Figure 23 ).
Step 2: Press the three programming buttons
to enter ADJUST mode ( Figure 25 ). Press ITEM to
select the programming item, and the arrow keys to
adjust the setting. TARGET TANK is desired tank
temperature. Recommended settings with a desired
tank temperature of 125°F:
Example DHW Programming
Item F° C°
MODE 3 3
BOIL TARGET 140°F 60°C
TARGET TANK 125°F 52°C
DIFF TANK 2°F 1°C
BOIL MASS 1 1
DIFF 2°F 1°C
DLY 5:00 5:00
F° F° °C
Step 4: See Section 6.4.11 Limit Controls.
Set both high limits 25°F / 14°C higher than BOIL
TARGET to allow for temperature rise across heat
exchanger. Manual high limits on water heaters have
a maximum 200°F / 93°C setting. (If water must be
at 175°F / 79°C or higher with a volume water heater
model, use mode 1. For volume water applications
exceeding 200°F / 93°C, contact the factory.)
Fine tuning: For faster staging, increase BOIL
TARGET setting. Larger DIFF TANK and DIFF
settings will slow response to demand, but may save
energy.
If unit short cycles, enter Advanced
Programming mode ( Section 6.4 ) and increase
BOILER MAX setting to the BOIL TARGET setting
or higher. Set BOILER MIN to 120°F / 49°C, and
STGMODE to PID. See Section 6.4.12 Advanced
Programming Mode to enter Advanced Programming
mode, or contact the factory for assistance.
EXAMPLE 2
Figure 26. Temperature Control Symbol Description.