LAARS EBP 175 MBTU/h - Installation, Operation and Maintenance Instructions - Manual (Page 24)

Page 24 LAARS Heating Systems
time. This is the length of time that the Endurance
pump will run after the call for heat has ended. It can
be used to purge heat from the boiler, putting it into the
system or transfer tank. It is adjustable from 0 to 10
minutes, and the default value is 3 minutes.
NOTE: Some systems are designed such that the
Endurance pump will be left with only the internal
recirculation path when a call for heat has ended.
Make sure the system design is known before setting
a pump time delay, so that the water has a path
during the purge time.
6.4.4 “Oar” Outdoor Reset
Outdoor reset can be turned on and off using the
“Oar” parameter. You must have an outdoor sensor,
properly located, to use this function.
IMPORTANT NOTE: The Endurance outdoor reset
is limited, to ensure that internal water temperature is
high enough to prevent heat exchanger condensation
and to keep the temperature of the water in the
20 gallon transfer tank high enough to serve the
domestic water plate heat exchanger at all times.
This feature is not meant to replace or mimic a
system outdoor reset controller.
6.4.5 “Oal” Minimum Outdoor
Reset Point
The “Oal” parameter tells the controller what
the minimum allowable supply temperature can be,
regardless of the outdoor reset calculation.
The default setting is 170°F (77°C) and it is
adjustable 170-200°F (77-93°C). The Endurance must
be able to keep the transfer tank at a high enough
temperature to generate the domestic water through the
DHW heat exchanger.
6.4.6 “rc” Outdoor Reset Ratio
The outdoor reset ratio is shown as “rc” in the
display. The ratio determines part of the relationship
between the outdoor temperature and the Endurance
supply temperature. It is adjustable between 0.1 and
5. The reset number represents the increase in the
Calculated Setpoint (CSP) for every degree below the
warm outdoor shutdown temperature.
The boiler control calculates CSP = Oal + (oTo –
air temp) x rc.
6.4.7 “oTo” Warm Outdoor Shutdown
When in the outdoor reset function is on, the
control has the ability to shut down the boiler system
when the outdoor temperature sensor reads the “oTo”
temperature that is set. This parameter is adjustable
from 55°-70°F (13°-21°C) and has a default setting of
65°F (18°C). The warm outdoor shutdown feature will,
not affect the generation of domestic water.
6.4.8 “unI” Temperature Units
The control has the ability to display and be
programmed in both °F (Fahrenheit) or °C (Celsius).
The “unl” lets the user choose between °F and °C.
6.4.9 “Dif” Burner On Differential
The differential between the Burner Control
Point and the Burner On Point is shown as “Dif” in the
display. If the Endurance reaches the Burner Off Point
Figure 33. Flow Schematic.