LAARS EDN Series - Installation, Operation and Maintenance Instructions - Manual (Page 25)

Endurance Page 25
6.4. These do not show on the control display, but it
is helpful to know how they affect the control logic of
the Endurance units.
6.5.1 ACV Release (EBP only)
When the EBP is in tank charge mode, and there
is a call for space heating, the EBP needs to know
at what temperature it can release the ACV (anti-
condensing valve) back to the space heating position,
allowing the hot water to go into the system. The ACV
release point is the “burner off” point minus 5°F (3°C).
For example, if the “burner off” point is 190°F (88°C),
the ACV release point is 185°F (85°C). This means
that when the supply temperature reads 185°F (85°C)
in the tank, it will release the ACV for heating mode.
6.5.2 Tank Charge Setting (EBP only)
When the temperature at the tank sensor goes
below the tank charge setting, the EBP will be in
“tank charge” mode. The tank charge setting equals
the programmed “burner off” point minus a fixed
40°F (22°C) differential. For example, if the “burner
off” point is 190°F (88°C), the EBP will go into “tank
charge” mode when the tank sensor reads below 150°F
(66°C). The ACV will close, and the EBP will run to
bring the supply temperature up to 185°F (85°C), and
the ACV will be released back to the space heating
mode (as long as there is no call for domestic hot
water).
6.5.3 Burner On Point
The “Burner On” point is calculated by
subtracting the “Burner On Differential (Dif)” from the
“Burner Control Point.” For EBP units the differential
is fixed at 13°F (7°C) and for EDP/EDN units, it is
adjustable (shown as “Dif” in the setup menu) from
4°-30°F (2°-17°C). This value tells the Endurance
when to re-energize during a call for heat in which the
Endurance reached its “Burner Off Point.”
6.5.4 Modulation Point
During a call for heat, the Endurance will ignite
at low fire and will begin to modulate to match the
load as it approaches the “Burner Control Point.”
There is no fixed temperature when this will occur, and
this value is not displayed on the Endurance.
6.6 Other Control Functions
6.6.1 Using Buttons on Control
Figure 30 shows a drawing of the control,
including the placement of the four buttons. Table 4
shows the actions associated with each of the buttons.
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.
For EDP/EDN units, the default setting is 170°F
(77°C) and it is adjustable 155-200°F (68-93°C).
For EBP units, the default setting is 170°F (77°C)
and it is adjustable 170-200°F (77-93°C). Note that
the difference between EBP and EDP/EDN adjustment
ranges is because the EBP units 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,
of course, not affect the generation of domestic water
in the EBP models.
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
during a call for heat, and the call for heat continues,
this differential will determine at what point below
the Burner Control Point the Endurance will energize
again. In the EBP models, this differential is fixed
at 13°F (7°C) to ensure that the transfer tank will
be properly charged. In the EDP/EDN models, this
differential is adjustable 4°-30°F (2°-17°C).
6.5 Calculated Control Values
There are several control values that are not
directly set by the user, but are calculated by the boiler
control, once the user has set the parameters in Section