11 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. The control 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) heat/loop demand connections available on this control. These inputs tell the boiler to provide water for space heating. Each demand connection has its own set point and outdoor air reset curve. When multiple demands 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.
CAUTION When multiple temperature loops are 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.
SMART SYSTEM Multi-temp loop control
The Knight wall mount boiler is capable of producing up to three (3) set point temperatures to meet different space heating demands. This device controls the temperatures of up to three (3) separate loops, based on the settings for the three (3) heat/loop demands (reference Lochinvar kit RLY30086).
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Installation & Operation Manual
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. When a boiler is programmed for DHW Normal Mode, the maximum firing rate can be limited to match the input rating of the indirect tank coil.
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. For stand-alone boilers, if the space heating call is still active 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, or the boiler goes into Freeze Protection Mode. It may be programmed to run during a DHW call for heat when the DHW is programmed for Zone 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 and/ or a DHW call for heat.
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.
