Installation & Operation Manual
11 Operating information
Monitor external limits
Connections are provided on the connection board for external limits such as flow switch, low water cutoff, gas pressure switches, and an auxiliary device proving switch. The SMART SYSTEM will shut off the burner and inhibit relighting whenever any of these external limits open.
Run-time and alarm outputs
The boiler provides dry contacts for indicating when the boiler is running, and when it is unable to operate.
Run-time and cycle counting
The control uses two timers to monitor the total hours of burner operation. One timer monitors the time the boiler is firing under 50% of rate. The other timer monitors the time the boiler is firing over 50% rate.
The control uses four (4) ignition counters to monitor the amount of boiler cycles. The first counter counts all ignitions of the control. The second counter counts only ignition attempts that have failed. The third and fourth counters are the same as the first and second respectively, but can be reset by the installer.
Service reminder
The control can be programmed for service reminder notification. This notification will become active when either a set time frame has expired, or a set amount of running hours or cycles has expired (all adjustable by the installer). The display will alternate the standard text on the display screen with Service Due every 5 seconds. The service reminder notification can be reset by the installer.
Error logging
The control will hold in memory the last 10 error codes as well as the last 10
Boiler temperature regulation
Operating temperature (target)
The SMART SYSTEM control module senses water temperature and regulates boiler firing and firing rate to achieve a target temperature. The target temperature can be set between 70°F (21°C) and 190°F (88°C).
•Target temperature is fixed when the outdoor sensor is not installed.
•Target temperature is calculated as described on this page under “Outdoor Reset Operation” and “Target Temperature Boost” when the outdoor sensor is connected.
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High limit operations
When outlet temperature exceeds 200°F (93.3°C), high limit action occurs. The boiler shuts down until the outlet water cools down.
Low water cutoff protection
1.The SMART SYSTEM control module uses temperature sensing of both supply and return areas of the heat exchanger. If the flow rate is too low or the outlet temperature too high, the control module modulates and shuts the boiler down. This ensures boiler shutdown in the event of low water or low flow conditions.
2.Some codes and jurisdiction may accept these integral features of the control in lieu of requiring an additional limit control or low water cutoff. Consult local jurisdiction to determine. A low water cutoff is available from the factory (WTR20009).
Outdoor reset operation, if used
Target temperature with outdoor reset
This feature improves the system’s efficiency as the outdoor temperature warms up.
See the Knight XL Service Manual to change the settings.
Reset curve
The reset curve looks at outdoor air temperature and adjusts the set point.
Cascade
When multiple boilers are installed, they can be wired together in a cascade sequence. A maximum of eight boilers can be controlled from a single control. In this application one boiler would be designated as the Leader control and all others would be designated as Member controls.
Once the Leader boiler receives a call for heat from a room thermostat, the control will determine what the set point will be. If outdoor air reset is desired, connect the outdoor air sensor to the terminals on the Low Voltage Connection Board on the Leader boiler. The set point will be calculated based on the programmed reset curve parameters. See the Knight XL Service Manual to program the reset curve. If outdoor air reset is not desired, do not connect the outdoor air sensor. A fixed temperature set point can be programmed into the control. See page 54 of this manual to program the set point.
