Lochinvar 400-801 operation manual Outdoor reset operation, if used, Cascade

Page 42

Outdoor Knight XL Installation & Operation Manual

8 Operating information

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 (WTR30024).

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 Outdoor Knight XL Service Manual to change the settings.

Reset curve

The reset curves look at outdoor air temperature and adjusts the set points.

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. The Leader control can be programmed to use Lead/Lag or Efficiency Optimization control methods.

Once the Leader boiler receives a call for heat from a room thermostat, BMS, or Modbus, 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 Outdoor 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 59 of this manual to program the set point.

If the water temperature at the system supply sensor is less than the set point + the turn-off offset - the off-on differential, then the control will initiate a call for heat on the Cascade (see the Outdoor Knight XL Service Manual for an explanation of the offset and differential). The Leader will energize the lead boiler on the Cascade. For a new startup this will be the Leader boiler.

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Sequence of the cascade

To equalize the run time of all boilers on the Cascade, the firing sequence will automatically be changed at set intervals.

The sequence will be changed once every 24 hours. The switching on/off sequence will be as follows:

TIME

SWITCHING ON SEQUENCE

 

 

Start

L-M1-M2-M3-M4-M5-M6-M7

 

 

1 hour

M1-M2-M3-M4-M5-M6-M7-L

 

 

2 hours

M2-M3-M4-M5-M6-M7-L-M1

 

 

If a boiler locks out or is used to heat an indirect DHW tank, it will automatically be given the lowest priority for the rest of that 24 hour period.

DHW, Night Setback, and Ramp Delay operation with cascade

For normal mode DHW operation any boiler(s) in the Cascade can be selected to provide heat for a DHW call. Select a boiler to be designated as the DHW boiler. Connect the DHW thermostat or sensor to the terminals on the Low Voltage Connection Board marked for the corresponding device. When the boiler receives a DHW call, the Leader control will take that boiler out of the Cascade sequence. If another boiler is available, the Leader will start it up to take its place.

The DHW boiler will adjust its set point to the programmed DHW boiler set point and will adjust its firing rate to maintain this. Once the DHW call has been satisfied, the Leader control will place that boiler back into the Cascade sequence.

Switching of the boiler between DHW operation and SH operation when there is a call for both does not occur in Cascade Mode.

When DHW is programmed for Zone Mode, connect the DHW thermostat or tank sensor to the Leader boiler. When a DHW call is received, the Leader will modulate the entire Cascade to bring the system supply temperature up to the DHW boiler set point (if higher).

Night Setback operation of the boilers within the Cascade is available. Programming of the Night Setback will be done through the Leader boiler. Refer to the Outdoor Knight XL Service manual for information regarding Night Setback.

Ramp Delay operation of the boilers as described in the Outdoor Knight XL Service Manual is available when the boilers are part of a Cascade system.

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Contents
Outdoor Knight XL Models 400 Contents When servicing boiler Please read before proceedingOutdoor Knight XL How it works Stainless steel heat exchangerModel Models 601 Ratings Outdoor Knight XL Boiler Ahri RatingInstallation must comply with Determine boiler locationBefore locating the boiler, check Flooring and foundation Provide clearancesOutdoor vent / air intake location Prevent combustion air contaminationInstall flue pipe assembly Models 400 Prepare boilerRemove boiler from wood pallet 3Install flue pipe assembly Models 701 Models 7014Installing Propane Orifice Model Gas conversions ModelModels 601 Leveling the boilerHydronic piping TEE with 1 Fitting on TOP Nipple Close Nipple Flow switch adjustment Near boiler piping componentsNear boiler piping connections Circulator sizingVariable speed pump option Head Feet Pressure20F 25F 30F 35F Model 7Single Boiler Multiple Temperatures 8Single Boiler Primary/Secondary Piping Number of Units Manifold Pipe Sizes in Inches mm10Multiple Boilers Primary/Secondary Piping Temperature Wires to Loop Sensors 120VAC to Connecting gas supply piping Gas connectionsNatural gas Propane GasCheck inlet gas supply InchesGas valve replacement Gas pressureLine voltage connections Field wiringInstallation must comply with Low voltage connectionsLow gas pressure switch Outdoor temperature sensorHigh gas pressure switch ThermostatWiring of the cascade Flow switchAlarm contacts ModBus3Low Voltage Field Wiring Connections Condensate disposal Condensate drainCheck/control water chemistry Freeze protection when usedStart-up Fill and test water systemInspect/fill condensate system Check for gas leaksCheck thermostat circuits Inspect/check condensate lines and fittingsIf boiler does not start correctly Final checks before starting the boilerStart the boiler Check system and boilerFor Your Safety Read Before Operating Set space heating operation Natural Gas PropaneVerify DHW mode Set domestic hot water DHW operationConfiguration of the cascade How the boiler operates Operating informationGeneral How the control module operatesTemperature control Protection featuresBoiler temperature regulation Outdoor reset operation, if used CascadeSequence of operation Operation DisplayStandby, ready to start a new cycle Outdoor Knight XL control module Access modesInstaller UserCall for Heat Information Dial Function Maintenance Maintenance and annual startup Service technicianOwner maintenance Maintenance Check expansion tank Flue vent system and air pipingCheck water system Check boiler relief valveCheck control settings Check ignition ground wiringCheck all boiler wiring Inspect ignition and flame sense electrodesReview with owner Check flame signalCleaning boiler heat exchanger Model Kit Part Component Number DescriptionDiagrams High Voltage2Ladder Diagram