Lochinvar Understanding Cascade Setup for Efficient Boiler Operation
Page 67

Installation & Operation Manual

11 Operating information (continued)

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 Wall Mount 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. 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 Knight Wall Mount 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 62 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 Knight Wall Mount 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.

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 change every hour during the first 24 hours, after that 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 is used to heat an indirect DHW tank, or locks out, 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.

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 Knight Wall Mount Service manual for information regarding Night Setback.

Ramp Delay operation of the boilers as described in the Knight Wall Mount Service Manual is not active when the boilers are part of a Cascade system.

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Contents Models WH 55 Contents Boiler water When servicing boilerPlease read before proceeding Boiler operationStainless steel heat exchanger Knight Wall Mount Boiler How it worksModels 55 Knight Wall Mount Boiler Ahri Rating RatingsBefore locating the boiler, check Installation must comply withCloset and alcove installations Determine boiler location1Closet Installation Minimum Required Clearances Prevent combustion air contamination PrecautionsVent and air piping Wall mounting locationProducts to avoid When using an existing vent system to install a new boilerAreas likely to have contaminants When removing a boiler from existing common vent system Remove boiler from wood pallet Prepare boilerGas conversions Mounting to a metal studded wall Mounting the boilerMounting to a wood studded wall Mounting to a concrete wallDirect venting options Sidewall Vent General ventingAir intake/vent connections Install vent and combustion air pipingModel Max Vent Air Requirements for installation in CanadaSizing Model Kit Number Equivalent Vent LengthAir inlet pipe materials MaterialsAir contamination Optional room airVent fittings Approved PVC/CPVC Vent Pipe and FittingsMaterial Standard Vent pipePolypropylene ModelCentrotherm InnoFlue SW Duravent Polypro Stainless steel vent Determine location If using the alternate sidewall terminationSidewall direct venting Vent/air termination sidewall2AClearance to Gravity Air Inlets Prepare wall penetrations Model Air Vent Centerline WidthMultiple vent/air terminations Prepare wall penetrations Alternate Field Supplied OptionSidewall termination optional concentric vent Sidewall termination installationDescription and usage Sidewall termination optional concentric vent models 92 and 3 Concentric Vent Dimensional Drawing reference D onMultiventing sidewall terminations 12Concentric Vent Sidewall AttachmentVent/air termination vertical Vertical direct ventingPrepare roof penetrations Vertical termination optional concentric vent Vertical termination installationMinimum Combustion AIR Typical Multiventing vertical terminationsExisting vent as a chase Alternate vertical concentric ventingVent / Air Inlet Size Minimum Existing Vent / Chase Size Concentric Venting ArrangementChilled water system Hydronic pipingSystem water piping methods General piping information Low water cutoff deviceNear boiler piping components Circulator sizing Near boiler piping connectionsPump Size Grundfos 20F Temperature Rise Applications25F Temperature Rise Applications 35F Temperature Rise ApplicationsVariable speed pump setup Smart System / Multi-temperature loop control optionVariable speed pump option 3Single Boiler Primary / Secondary Piping Make UP Water Indirect Number of Units Boiler Member 8Single Boiler Multiple Temperature DHW Priority Model Required Pipe Sizes Boiler Make UP Boiler Gas connections Connecting gas supply pipingPropane Gas Natural gasCheck inlet gas supply Natural Gas Pipe Capacity ChartLength of Pipe in Straight Feet for 1/2 PSI Gas Pressure Gas valve replacementInstallation must comply with Low voltage connections Field wiringLine voltage connections Thermostat Outdoor temperature sensorLouver proving switch Flow switchBoiler management system Alarm contactsWiring of the cascade System supply sensorFieldwiring InstallationCondensate drain Condensate disposalFill and test water system Freeze protection when usedStart-up Check/control water chemistryInspect/check condensate lines and fittings Clean/Inspect Trap AssemblyCheck for gas leaks Inspect/fill condensate system Check thermostat circuitsCheck system and boiler Final checks before starting the boilerStart the boiler If boiler does not start correctly2Operating Instructions Models 55 Operating Instructions Model Natural Gas Propane Set space heating operationConfiguration of the cascade Verify DHW modeSet domestic hot water DHW operation General Operating informationProtection features Boiler temperature regulation Cascade Outdoor reset operation, if usedOperation Display Sequence of operationInstaller Access modesUser 1Control Panel Knight wall mount boiler control moduleCall for Heat Information Dial Function See the following pages for instructions General Maintenance Maintenance and annual startupService technician Owner maintenanceMaintenance Flue vent system and air piping Check ignition ground wiringCheck all boiler wiring Check control settingsCheck burner flame Check flame signalCleaning boiler heat exchanger Perform start-up and checksPC Interface Diagrams2Wiring Diagram

WH 55-399 specifications

The Lochinvar WH 55-399 is a high-efficiency water heater designed for residential and commercial applications, offering a reliable solution for hot water needs. This model represents an advanced approach to water heating, combining cutting-edge technologies and features that ensure optimal performance and energy efficiency.

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In summary, the Lochinvar WH 55-399 stands out with its combination of high efficiency, advanced technology, and durable construction. Whether for residential or commercial use, this water heater provides a dependable and cost-effective solution for all hot water needs. Its innovative design and performance characteristics make it a top choice for anyone seeking a premium water heating option.
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