1
Service
Service Manual
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1
Service
(continued)
H: Control modes
SH controlling sensor
The SH controlling sensor parameter selects the sensor the
control will use to regulate the boiler firing rate. This
parameter is adjustable by the installer by accessing
parameter
H1
. The sensor selections are as follows: The
outlet sensor regulates the firing rate based on the outlet
water temperature of the boiler and the inlet sensor regulates
the firing rate based on the inlet water temperature of the
boiler. If the outlet sensor is selected, and the optional system
supply sensor is connected, the control will regulate the firing
rate based on the system supply sensor temperature. The
default sensor is the Outlet Sensor.
SH source
The SH source parameter selects the method used to control
the modulation of the boiler. This parameter is adjustable by
the installer by accessing parameter
H2
. The control methods
are as follows:
1 - Thermostat. The control modulates the boiler based on
the user set point and the temperature of the selected
controlling sensor.
2 - BMS (Building Management System). The control
modulates the boiler based on the 0 - 10 VDC signal delivered
to the appropriate terminals on the connection board. When
BMS is selected additional parameters for BMS operation
may need to be adjusted. These can only be accessed by the
optional PC software. See the Knight Smart System PC
Program Instructions Manual for additional BMS parameter
information.
3 - Cascade. The boiler is part of a group of boilers sequenced
together. The designated Leader boiler determines the total
output needed from the group based on the set point and
controlling sensor reading. It assigns portions of this output
to itself (Leader) and the Member boilers. When Cascade is
selected, each boiler in the group requires a unique address
(see below). The default control is Thermostat.
Boiler cascade address
The boiler designated as the Leader needs to be programmed
with address 0. All the Member boilers require addresses
from 1 to 7, and the addresses must be different for each
Member. The addresses can be in any order, regardless of the
order in which the units are wired together. This parameter
is adjustable by the installer by accessing parameter
H3
. The
outdoor air (if used) and system supply sensor must be
connected to the Leader boiler. The default address is 1.
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
H4.
The default max.
cascade set point is 185°F (85°C).
Figure 1-2
Ramp Delay Interval
% RATE
RAMP 6
RAMP 5
RAMP 4
RAMP 3
RAMP 2
RAMP 1
CALL
FOR
HEAT
TIME
1
TIME
2
TIME
3
TIME
4
TIME
5
TIME
6
MINUTES
Содержание KNIGHT 399 - 800
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