Lochinvar SNA285-125, SNA500-125 Operating information, General, How the water heater operates

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TM

Installation & Service Manual

11 Operating information

General

How the water heater operates

The Shield water heater combines an advanced stainless steel heat exchanger, electronic control module, and tank that allows fully condensing operation. The blower pulls in air and pushes flue products out of the heat exchanger and flue piping. The control module regulates blower speed to control the water heater firing rate. The gas valve senses the amount of air flowing into the water heater and allows only the right amount of gas to flow. An internal pump circulates the water between the tank and heater and mixes the incoming water to provide maximum efficiency.

Temperature control

Modulation

The Shield water heater is capable of modulating its firing rate from a minimum of 20% to a maximum of 100%. The firing rate is dictated by the hot water draw and various other temperature limitations.

Night setback

The controller may be programmed to reduce the tank set point during a certain time each day. A start and stop time can be programmed for each day of the week.

Flame current support

To prevent nuisance shutdowns when the water heater is firing at minimum rates, the control will increase fan speed when the flame signal drops too low.

Protection features

Outlet temperature, flue temperature, and temperature rise limiting

The heat exchanger outlet temperature is monitored by the heat exchanger outlet temperature sensor. When the heat exchanger outlet temperature exceeds 190°F, the unit will reduce the fan speed. If the heat exchanger outlet water temperature exceeds 198°F the control will shut the unit down until it cools off.

The control module monitors the flue temperature by a sensor located in the flue exhaust. If the flue temperature exceeds 215°F the control will reduce the maximum fan speed. If the flue temperature exceeds 240°F the control will shut the unit down. The unit will restart automatically once the flue temperature drops 25°F and the minimum off time has expired.

The control monitors the temperature difference between the heat exchanger inlet and the heat exchanger outlet sensors. If this difference exceeds 25°F the control will reduce the fan speed. If the temperature difference exceeds 30°F the control will shut the unit down. The unit will restart automatically once the temperature difference has dropped below 25°F and the minimum off time has expired.

Freeze protection

DO NOT install the water heater in a room likely to freeze.

The following integral feature of the electronic control module provides some protection for the water heater.

• The electronic control module provides freeze-up protection as follows when the water heater water temperature drops below 45°F:

•Below 45°F, the internal pump operates constantly.

•Below 37°F, the burner turns on.

•The burner and pump will turn off if water heater water temperature rises above 45°F.

￿ CAUTION This feature of the electronic control module does not eliminate the possibility of freezing.

The installation must still use recognized design, installation and maintenance practice to prevent freeze potential for the water heater.

Monitor external limits

Connections are provided on the connection board for external limits. The electronic control module will shut off the burner and inhibit relighting whenever an external limit opens.

Runtime and alarm outputs

The water heater provides dry contacts for indicating when the water heater is running, and when it is unable to operate.

Error logging

The control will hold in memory the last 10 faults. The date and time of the occurrence will be recorded as well. Only the 10 most current occurrences will be held in memory.

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Contents What to do if YOU Smell GAS Installation & Service ManualContents Hazard definitions Please read before proceedingBlower Shield How it worksModels SNR150-100 -- SNA285-125 Model SNA500-125 Model SNA400-125CSA RatingsBefore locating the water heater, check Installation must comply withCloset and alcove installations Determine water heater location1Closet Installation Minimum Required Clearances Prevent combustion air contamination Flooring and foundationRemove water heater from wood pallet Do not install the Shield water heater into 3Combustion Air Direct from Outside Minimum Recommended Combustion AIR Supply to Equipment Room Direct venting options General ventingVent pipe and fittings Venting and combustion airCanada Air inlet pipe materials Air intake/vent connectionsVent and air piping Vent LengthRemoving from existing vent Vent Size If using the alternate sidewall terminationSidewall direct venting Vent/air termination sidewall2Clearance to Gravity Air Inlets Termination and fittings Prepare wall penetrationsPrepare wall penetrations Alternate Field Supplied Option 5AMultiple Vent Terminations must also comply with -1A Multiple vent/air terminationsDescription and usage Sidewall termination installationSidewall termination optional concentric vent 9Concentric Vent Dimensional Drawing Multiventing sidewall terminations 12Concentric Vent Sidewall AttachmentVent/air termination vertical Vertical direct venting2Vertical Terminations with Multiple Water Heaters Prepare roof penetrationsVertical termination optional concentric vent Vertical termination installationMultiventing vertical terminations 6Concentric Vent Roof Installation1Vertical Direct Venting w/Room Air Conventional and sidewall ventingGeneral piping information System pipingSystem water piping methods ScaldingDelta T Piping componentsWater chemistry Single Unit 3Multiple Units Water Tank Supply Gas connections Connecting gas supply pipingPropane gas Natural gasLength of Pipe in Straight Feet for 1/2 PSI Natural Gas Pipe Capacity ChartCheck inlet gas supply Gas pressure Gas valve replacementField wiring 3Low Voltage Field Wiring Connections Inputs Condensate drain Condensate disposalFinal checks before starting the water heater Start-upCheck for gas leaks Inspect/fill condensate system Check flame and combustion Start the water heaterIf water heater does not start correctly Check system and water heater2Operating Instructions Models SNR150-100 -- SNA285-125 3Operating Instructions Models SNA400-125 -- SNA500-125 General Temperature controlProtection features Operating informationSaving parameters Water heater temperature regulationAdjustable control parameters HTR Ignition Sequence of operation1Control Panel Shield control moduleStatus Display Screens Status display screensStatus Display Screens cont’d Owner maintenance Maintenance Maintenance and annual startupService technician Maintenance Check water heater relief valve Flue vent system and air pipingCheck water system Check expansion tankCheck flame signal Check ignition ground wiring Check burner flameCheck all water heater wiring Check control settingsNiosh stated First Aid Cleaning heat exchangerHandling ceramic fiber materials Oiled bearing circulatorsCheck the following TroubleshootingBefore troubleshooting Check control module fusesAbove 50% No DisplayNo Burner Operation Unit Does Not ModulateTemperature F Resistance Ω Checking temperature sensorsTroubleshooting No Flame Ign FlameSequence Fail No FlameRunning GV/RelayFan Speed Low Manual ResetHigh Limit Fan LowSensor Open SwitchFan High Fan Speed HighProgr ParametersWrite EEProm Service BlkWatch Dog Error Low 24 VACGas Supply Pressure Combustion Analysis ProcedureGas Valve Adjustment Or ObstructionModel SNA500-125 Gas valve adjustment procedureModels SNR150-100 -- SNA285-125 Model SNA400-125120 VAC DiagramsLOW Voltage

SNA400-125, SNR150-100, SNA285-125, SNR200-100, SNA500-125 specifications

Lochinvar has established itself as a leader in the realm of high-efficiency heating solutions, and its line of condensing boilers, including the SNA500-125, SNR200-100, SNA400-125, SNA285-125, and SNR150-100, exemplifies the brand’s commitment to innovation, efficiency, and reliability.

The SNA500-125 model stands out with its impressive heating capacity, designed for larger commercial applications. Featuring advanced modulating burners, it can precisely adjust its output based on real-time demand, significantly enhancing energy efficiency. The stainless steel heat exchanger ensures robust durability and improved thermal performance, while the integrated controls offer advanced diagnostic capabilities and user-friendly operation.

Next in the lineup, the SNR200-100 serves as a versatile option for mid-sized applications. Its compact design allows for flexible installation, making it a valuable choice for facilities with limited space. The boiler incorporates a high-efficiency combustion system that maximizes fuel utilization, while its low NOx emissions technology aligns with environmental standards, reducing the carbon footprint of users.

The SNA400-125 delivers a robust solution for diverse heating needs, equipped with state-of-the-art modulation technology that not only optimizes efficiency but also offers quiet operation – a crucial feature for facilities where noise reduction is paramount. This model also includes built-in redundancy options, enhancing reliability during peak operational periods.

The SNA285-125 provides a balance of performance and efficiency for smaller commercial settings. Its innovative control system offers precise temperature management and easy integration with existing systems. Energy Star certified, this model is not only cost-effective but supports sustainability efforts in various industries.

Lastly, the SNR150-100 is ideally suited for light commercial applications, featuring a compact footprint and excellent heat transfer capabilities. The user-friendly interface and robust safety features make it an excellent choice for operators prioritizing both ease of use and reliability.

All these models incorporate Lochinvar's commitment to superior design and advanced technologies, setting a benchmark in the high-efficiency heating market. With a focus on long-term performance and compliance with modern environmental standards, Lochinvar continues to deliver top-tier solutions tailored to meet diverse customer needs. Whether for large-scale operations or smaller settings, these boilers represent a significant advancement in commercial heating technology.
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