To troubleshoot a Lochinvar boiler, first record its exact model and the full fault message, then use the service manual for that boiler family. Lochinvar fault names, reset steps and diagnostic procedures vary by model, so there is no single code list or fix that safely applies to every unit. Homeowners can make a few non-invasive checks; work involving gas, combustion, internal wiring or safety controls belongs to a qualified heating professional.
Start with the exact boiler and fault message
Find the full model designation and serial number on the boiler’s identification label, and write down the display message or code exactly as shown. Record when it appeared and whether the boiler was calling for heat. These details help a technician identify the right service information and avoid applying a procedure from another model family.
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Lochinvar Corporation RLY30061 INTEGRATED CONTROL BOARD | $632.40 | Buy on Amazon |
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Lochinvar 100208458 Genuine OEM Control Board - User Interface | $380.19 | Buy on Amazon |
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Use Lochinvar’s official product literature and document lookup to find the installation and service manual for the matching series and model. Check that the document applies to your boiler’s model and region, and follow its revision-specific instructions. The WHB, KHB and Knight KB manuals have distinct troubleshooting charts; their code names and steps are not interchangeable.
What you can check safely
Keep homeowner troubleshooting to observation and basic controls, without opening the boiler cabinet or touching internal components.
#1 Best Overall
- Product Type: Control
- Confirm the thermostat is set to call for heat and note whether other heating zones are working.
- Read and record the display message, including any code, before taking action.
- If it is safe and the manual permits, check whether the accessible boiler switch or breaker appears to be off or tripped. Do not remove electrical covers or probe wiring.
- Look for visible water leaks or unusual sounds from a safe distance; report them to a service professional.
If the boiler is locked out, do not repeatedly reset it or try resets to bypass a safety condition. Some faults require a manual reset only after the cause has been corrected; the applicable manual specifies whether and how. If the fault returns, stop and arrange qualified service.
Common diagnostic categories—and what they mean
The categories below are useful context for describing a problem to a technician, not instructions to dismantle or repair the boiler. Exact checks, values and reset procedures depend on the model and its manual.
Rank #2
- Product Type: Module
Water flow and low-water cutoff
On the WHB, the service chart describes a “Flow Switch/LWCO” fault when an optional flow switch or low-water cutoff is not making. Its technician-directed checks include pump operation during a call for heat, closed valves or piping obstructions, and whether the system is full and purged of air. The chart specifies a manual reset after the condition is corrected. This fault name and reset guidance should not be assumed to apply to other Lochinvar boilers.
Venting, air intake and fan
WHB fan-speed troubleshooting points to vent or air-intake length, obstruction, wiring and fan operation. KHB and Knight KB manuals also contain their own vent-obstruction checks. Vent configuration and allowable lengths are model-specific; a qualified technician should consult the boiler’s applicable installation and service instructions rather than rely on a generic venting remedy.
Rank #3
- For use with WB 51, WB 81, WB 106, WB 151, WB 211, KB 81, KB 211, KB 106, KB 286, KB 151, Lochinvar parts, hydronic heater parts, Lochinvar, Knight, floor standing KB, wall-mount WB and WH
Temperature, overheating and circulation
Temperature and delta-T faults can lead a technician to check circulation, pump performance, air in the system, piping and sensors. The KHB and KB charts use their own fault terminology and procedures for temperature sensing, overheating and hydronic flow. Sensor measurements and other test specifications must come from the exact manual.
Electrical supply, controls and combustion
Voltage checks, internal wiring inspection, gas-pressure testing, combustion analysis, burner work and safety-control testing are professional service tasks. Do not remove covers, adjust the gas train, or attempt to test energized components. The manufacturer’s manual and a technician’s training govern the required instruments and procedures.
Rank #4
- KB080, KB105, KB150, KB210, KB285, KBX501, KBX601, KBX701, KBX801, OAN151-286, OAN400-601, OAN701-801Specifications
- Key Spec Includes: Control board, User interface
- Length: 7.5 in.
- Width: 4.7 in.
- Height: 3.4 in.
When to call a heating professional
Contact a qualified boiler or HVAC service provider for a recurring lockout, suspected venting or combustion issue, visible leak, abnormal noise, or any fault that calls for internal inspection or testing. Gas odor or a suspected gas leak requires immediate attention: leave the area and follow local emergency gas-safety guidance; do not operate switches or attempt a boiler reset.
When arranging service, provide the model and serial number, exact display message, and what you observed. You can ask whether the provider has experience with your Lochinvar model and will document the fault and test results against the official service manual. Do not order a replacement pump, sensor, control board, pressure switch or igniter based on a generic code description; parts identification depends on the exact boiler and its literature.
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- Integrated Ctrl Module, Lochinvar EnergyRite Heaters, 152-252
- 100286274
Lochinvar support tools and manuals
Lochinvar’s Tools for Success page includes troubleshooting aids for the low-water cutoff and gas pressure switch, plus boiler simulators for Knight KHB and WHB. These are supplemental resources, not a substitute for the correct manual or on-site diagnosis. For fault-specific procedures and any service work, use documentation that matches the boiler’s series, model and region.
Quick Recap
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