Ignition failure on a Laars boiler means the burner cannot establish a flame within its attempt window, and the cause is usually narrower than it first appears.
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Quick answer
Ignition failure on a Laars boiler means the control system attempted to light the burner but did not detect a flame within its allowed window, and it is most often caused by a gas supply issue, a fouled or misaligned ignition electrode, incorrect gas pressure, a blocked burner, or a faulty ignition control module. The boiler will typically go into a lockout after a set number of failed attempts as a safety measure. A licensed gas fitter isolates the true cause with gas pressure testing, electrode inspection, and control board diagnostics rather than by trial and error.
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When a Laars boiler calls for heat, the sequence involves purging air from the combustion chamber, opening the gas valve, energizing the igniter, and confirming a flame signal within a short window, typically a few seconds. If a flame is not detected, the control board will usually retry the sequence a limited number of times before locking out rather than continuing to attempt ignition indefinitely, since repeated unsuccessful attempts mean unburned gas is being introduced into the combustion chamber each time.
From a homeowner's perspective, this often shows up as the boiler attempting to start, making a clicking or humming sound, and then going quiet with a fault indicator on the display rather than producing heat.
Several of these causes produce very similar symptoms from the outside, meaning a boiler that will not ignite could equally be a gas pressure problem, an electrode problem, or a control board problem, and swapping parts without testing risks paying for a component that was never the actual issue. A proper diagnostic sequence checks incoming and manifold gas pressure first, since that rules out or confirms a supply-side issue quickly, then inspects the electrode and its gap and condition, then verifies the ignition module's signal and timing against specification.
| Observation | Possible direction | Safe homeowner action |
|---|---|---|
| Boiler clicks repeatedly but never fires | Electrode or ignition module issue | Note the number of clicks and sound pattern; call for service |
| Other gas appliances also seem weak | Gas supply or pressure issue affecting the home | Mention any other appliances affected when calling |
| Failure started right after nearby gas work | Air in the line or a pressure change | Tell the technician about the recent work and its timing |
| Intermittent ignition, sometimes fires, sometimes doesn't | Marginal electrode or pressure fluctuation | Note the pattern of when it works versus when it doesn't |
A proper visit starts with confirming the fault history from the control board where available, then testing incoming and manifold gas pressure with a manometer, inspecting the ignition electrode's condition and gap, and checking the ignition module's output against the manufacturer's specification. Depending on findings, the fix might be as simple as cleaning or re-gapping the electrode, or it might involve addressing a gas supply issue that goes beyond the boiler itself. Because this work involves gas piping, combustion, and safety controls, it must be performed by a Technical Safety BC licensed gas fitter.
Safety note
If you ever smell gas, hear a hissing sound near the unit, or notice soot or a burning smell near the appliance, leave the home immediately and call FortisBC at 1-800-663-9911 from a safe location before doing anything else. Diagnosing and repairing ignition failure on a gas boiler must be done by a Technical Safety BC licensed gas fitter.
Repeated clicking without a flame usually points to the igniter attempting a spark that either isn't reaching the burner properly or isn't being followed by adequate gas flow, which can stem from an electrode issue, gas pressure, or a control fault. A technician can isolate which one with testing.
Yes, unusually low incoming gas pressure, sometimes caused by another appliance drawing gas at the same time or an issue upstream of the boiler, can prevent reliable ignition even when the boiler's own components are functioning correctly.
This is set by the control board and varies by model, but boilers are generally designed to make a limited number of attempts before locking out rather than trying indefinitely, since repeated failed attempts introduce unburned gas each time.
Yes, a fouled, cracked, or misaligned electrode is one of the more frequent causes, since it prevents a reliable spark from forming even when gas supply and pressure are otherwise normal.
Modern Laars condensing boilers use electronic ignition rather than a standing pilot, and troubleshooting the ignition sequence involves gas pressure testing and component inspection that should be left to a licensed gas fitter rather than attempted at home.
Yes, air introduced into the gas line during nearby work, such as a meter replacement or a new appliance hookup, can temporarily affect ignition reliability until it clears or is purged properly by a licensed technician.
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