Hot-surface igniter

If you smell gas, leave the building and call FortisBC at 1-800-663-9911 or 911 from outside before anything else. FortisBC's guidance is to treat a rotten-egg smell as a gas emergency: do not touch switches, do not reset the boiler and do not try to find the leak. Get outside first, then call from a safe place.

The igniter sits on the gas and combustion side of the boiler, and in British Columbia work on it is licensed gas work under Technical Safety BC. Homeowner checks stop at reading the display and picking up the phone; everything past that belongs to a licensed contractor working under permit.

A failed igniter is not a gas leak, but an ignition fault is still a gas-system fault. The element runs hot enough to burn skin, the surrounding parts carry gas, and the circuit that proves flame is a safety device. Never open the combustion chamber or handle the igniter yourself.

On a call for heat the control runs its safety checks, starts the combustion fan to purge the chamber, then energizes the hot-surface igniter. The element heats to glowing temperature; when the control sees the igniter's current reach its expected level, it waits a short dwell and opens the gas valve. Gas meets the hot element, the burner lights, and the igniter switches off as soon as the control proves flame.

Laars' Mighty Therm2 manual describes this sequence for its hot-surface system: the ignition control verifies igniter current, dwells, opens the gas valve for a four-second trial, and shuts the igniter off once a flame signal is detected. On that line the igniter and flame sensor are the same part on the smaller sizes, while the largest models use two igniter/sensor assemblies.

Hot-surface ignition has largely replaced spark ignition and standing pilots on modern equipment because there is no open spark and no continuously burning pilot. Laars' Pennant installation and operation instructions describe the staged commercial line using hot surface igniters, one per stage pair, and Weil-McLain's Canadian parts catalogue includes hot-surface ignition modules among its service parts. Older Viessmann Vitogas 050 ECD manuals exist in both standing-pilot and hot-surface-ignition versions, a reminder that the same boiler family can be built either way.

Hot-surface igniters are wear items. The ceramic body can crack from thermal cycling, the element can burn open or drift in resistance, and the connector or lead can corrode. Dust, condensate and combustion debris on the element can also stop it reaching ignition temperature even though it still glows faintly.

A weak igniter usually shows up as an ignition lockout: the boiler runs its purge, calls for heat, and the burner never lights. Some controls report the failure directly, while others retry a set number of times and lock out. The boiler's display text or code is the most useful clue a homeowner can write down.

Ignition problems are not always the igniter. A closed manual gas valve, an unpurged gas line after service, a faulty ignition module, poor grounding or a dirty flame sensor can produce the same lockout. That is why technicians test the ignition circuit rather than replacing the element on sight.

Note the exact alert text or code, whether the boiler retries, and whether other gas appliances are working. A whole-house gas interruption points at supply, not the boiler. If the boiler lights sometimes and not others, say so when you call, because intermittent behaviour changes the diagnosis.

Never reset a gas boiler repeatedly to force it to light, and never open the burner compartment to look at the igniter. If you smell gas at any point, the safety-first step above overrides everything else.

Keep the boiler area clear and the vent terminals unobstructed. Laars cautions that the igniter gets hot and that replacement requires a new igniter gasket, which is exactly why this part is fitted by a technician with the correct replacement rather than improvised.

A technician confirms the call for heat and the control's sequence, then tests the igniter circuit: supply voltage, igniter current or resistance against the manufacturer's specification, and the condition of the ceramic and connector. Laars' manual walks through replacing the igniter/sensor by shutting off power, disconnecting the plug, removing the flange screws and fitting a new gasket with the replacement.

If the igniter tests good, the technician moves to gas supply, the ignition module, grounding and the flame-sensing circuit. After any repair the boiler is fired several times and combustion is verified with an analyser before the job is finished.

Ignition faults are one of the most common no-heat calls ROMA Heating & Cooling attends, and most end with a new igniter, lead or module rather than a new boiler. Call for a diagnosis rather than living with lockouts through the heating season.