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Operating information
General
How the boiler operates
The Knight wall mount boiler uses an advanced stainless
steel heat exchanger and electronic control module that
allows fully condensing operation. The blower pulls in air
and pushes flue products out of the boiler through the heat
exchanger and flue piping. The control module regulates
blower speed to control the boiler firing rate. The gas valve
senses the amount of air flowing into the boiler and allows
only the right amount of gas to flow.
How the control module operates
The SMART SYSTEM control module receives inputs
from boiler sensors and external devices.
module activates and controls the blower and gas valve to
regulate heat input and switches the boiler, Domestic Hot
Water (DHW), and system pumps on and off as needed.
The user programs the module to meet system needs by
adjusting control parameters. These parameters set operating
temperatures and boiler operating modes. Boiler operation
can be based on boiler outlet water temperature, boiler inlet
water temperature, system temperature, a 0 - 10V signal, or
Modbus, depending on the parameter settings.
Control inputs and outputs
Space heating demands
There are three (3) thermostat connections available on this
control. These inputs tell the boiler to provide water for space
heating. Each thermostat connection has its own set point
and outdoor air reset curve. When multiple thermostats have
a call for heat the control will give priority to the demand
with the highest set point.
Example: Assume that both Heat/Loop Demand 1 and Heat/
Loop Demand 2 have a call for heat. Heat/Loop Demand 1
has a set point of 110°F. Heat/Loop Demand 2 has a set point
of 140°F. The boiler will regulate the system temperature to
140°F until Heat/Loop Demand 2 has been satisfied. Once
Heat/Loop Demand 2 has been satisfied the boiler will
provide 110°F water to the system.
When multiple temperature loops are
CAUTION
used, thermostatic mixing valves are
required for the protection of any low
temperature loops.
0 - 10V input (set point or power)
The Knight wall mount boiler can be controlled by a Building
Management System (BMS) using a 0 - 10 vdc signal. The
control can be configured by the installer to use this signal to
either control set point or firing rate.
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The Knight wall mount boiler can also be programmed to
accept a call for heat from a 0 - 10V signal, reference the Knight
Wall Mount Service Manual for a detailed explanation of this
procedure.
DHW priority
The SMART SYSTEM control allows the connection of a DHW
thermostat or tank sensor to the low voltage connection board.
When a tank sensor is connected, the DHW thermostat input
is ignored.
DHW / space heating (SH) cycling
If a DHW call for heat is received while a space heating call is
in progress and the DHW is in Normal Mode, the control will
start the DHW pump and shut the boiler pump off. The system
pump will remain on. If the space heating call is still active
The control
while the DHW call is in operation, the control will wait for 30
minutes (time adjustable by installer) then it will switch back to
the space heating demand. There is a timer to switch from space
heating to DHW and a timer to switch from DHW to space
heating. The control will switch back and forth until one of the
heat demands end.
Programmable controlling sensor
The control module is programmed to use the outlet sensor
as the control sensor by default. If a system supply sensor
is connected, the control automatically uses it as the control
sensor. The control sensor can be changed by the installer to
the inlet sensor. If the inlet sensor is chosen as the controlling
sensor, it is recommended that the system supply sensor
be installed in order to provide the best control of the inlet
temperature.
Anti-cycling
After the burner turns off, the control will delay the next burner
cycle for a set time period (time is adjustable by the installer).
The time delay will be bypassed if the inlet water temperature
drops too far during the delay.
Boiler and system pump control
The boiler pump will run whenever the burner is firing, unless
the DHW is programmed for Normal Mode and the boiler is
heating the DHW tank. The boiler pump will run during Freeze
Protection Mode as well. It will continue to run for a short time
after the burner turns off or the Freeze Protection Mode ends.
The system pump will run whenever there is a space heating call
for heat, a DHW call for heat when the DHW is programmed
fo5r Zone Mode, or the boiler goes into Freeze Protection
Mode. It will continue to run for a short time after the end of
the heat demand or the Freeze Protection Mode. The system
pump can be programmed to run continuously if desired,
except during outdoor shutdown.
Temperature control
Modulation
The Knight wall mount boiler is capable of modulating its firing
rate from a minimum of 20% to a maximum of 100%. The
firing rate is dictated by the call for heat (i.e., space heating or
domestic hot water), the heating load, ramp delay (if enabled),
and various other temperature limitations.
Installation & Operation Manual
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