Lochinvar Power-fin 1701 - Manual (Page 20)

1
Service
20
Service Manual
Max. cascade set point
This parameter determines the set point used by the individual
boilers in a Cascade. When a boiler is commanded to fire by the
Leader boiler, it will attempt to achieve this temperature at its
outlet. The Leader boiler will limit the modulation of the last
boiler to fire in order to hold the temperature at the system
supply sensor to the user set point. If any of the boiler outlet
temperatures reach the max. cascade set point, the boiler will
then modulate down on its own in order to keep its outlet
temperature within the max. cascade set point. Therefore, this
parameter can be used to limit the outlet temperatures of all the
boilers in a Cascade. Note that this parameter does not apply
when the boiler is heating an indirect DHW tank. This
parameter is adjustable by the installer by accessing parameter
I2. The temperature range for this parameter is 32°F (0°C) -
261°F (127°C). The default max. cascade set point is 185°F
(85°C).
Cascade offset (boilers only)
This parameter determines how much the temperature must go
above set point before the lead boiler will turn off. This
parameter can be adjusted by the installer by accessing
parameter I3. The temperature range for this parameter is 0°F
(0°C) - 54°F (30°C). The default value is 9.9°F (5°C).
Cascade off-on differential (boilers only)
This parameter determines how much the temperature must go
below the turn off temperature (Set point + Offset) before the
lead boiler turns on. This parameter can be adjusted by the
installer by accessing parameter I4. The temperature range for
this parameter is 0°F (0°C) - 54°F (30°C).The default value is
19.8°F (11°C).
J: Building Management System (BMS)
BMS type
When the unit or cascade is controlled by the 0-10V BMS input,
the voltage signal can control either the modulation rate
(power) (B9 or M9 only) or the set point. This parameter may
be adjusted by the installer by accessing parameter J1. The
default value is Power.
Voltage at minimum
This setting determines the voltage at which the external signal
begins to increase either the modulation or the set point. Below
this voltage, the modulation or set point will be at their
minimum values. This parameter can be adjusted by the
installer by accessing parameter J2. The range for this parameter
is 0V - (J3 - 0.1V). The default value is 2V.
Voltage at maximum
This setting determines the voltage at which the external signal
forces either the modulation or the set point to their maximum
value. This parameter, along with the previous parameter,
determines how much the modulation or set point changes as
the BMS input voltage changes. The modulation or set point
will change in proportion to the change in voltage between the
minimum and maximum voltage settings. This parameter may
be adjusted by the installer by accessing parameter J3. The range
for this parameter is (J2 + 0.1V) - 10V. The default setting is
10V.
Minimum power
This setting determines the modulation of the unit (B9 or M9
only) or cascade when the BMS input voltage is at or below the
Voltage at Minimum setting. This parameter is active only when
the BMS type is set to Power. On heaters with F9 firing controls,
this function does not apply. On heaters with B9 firing controls,
this parameter should not be less than 50%. On heaters with M9
firing controls, this parameter can be as low as 20%. When the
cascade function is also active, this parameter may be as low as
the minimum firing rate of the individual heaters divided by the
number of heaters in the cascade. This parameter may be
adjusted by the installer by accessing parameter J4. The range
for this parameter is 0 - 100%. The default value is 20%.
Maximum power
This setting determines the modulation of the unit (B9 or M9
only) or cascade when the BMS input voltage is at or above the
Voltage at Maximum setting. This parameter is only active
when the BMS type is set to Power. This parameter can be
adjusted by the installer by accessing parameter J5. The range
for this parameter is 0 - 100%. The default value is 100%.
Minimum set point
This setting determines the set point used by the unit or cascade
when the BMS voltage is at or below the Voltage at Minimum
setting. This parameter is only active when the BMS type is set
to Set Point. This parameter can be adjusted by the installer by
accessing parameter J6. The temperature range for this
parameter is 32°F (0°C) - 248°F (120°C). The default value is
70°F (21°C).