SSN24 – HOT SURFACE IGNITOR & FLAME SENSOR (HONEYWELL SMART VALVE)

If your furnace has a Honeywell Smart Valve and won’t light, this combined ignitor and flame sensor assembly is the part you need. It replaces the Q3400A1024 — a unique part that combines both ignition and flame sensing in one unit. Not compatible with standard 120V ignitor systems.

Replaces: Q3400A1024, 1009524, IG9500, SSN24

Fits: Furnaces with Honeywell Smart Valve systems using ignitor/sensor Q3400A1024.

Need help? See our Furnace Not Heating Guide.

In stock at Open To Public HVAC Parts in Dallas. We test parts at the counter before you buy. Call or text (214) 340-9421.

Specs

• StyleHot surface ignitor (HSI)
• ElementSilicon carbide
• ConnectorVerify with existing part
• MountBracket style

Cross-reference numbers

This part replaces the following OEM and aftermarket numbers:

• 1009524
• IG9500
• Q3400A1024

Not sure if your number matches? Call (214) 340-9421 or bring the old part in — bench-testing is free.

Fits these models

• HSI hot-surface-ignition gas furnaces (most 80%+ AFUE units from 1990s onward)
• Verify voltage rating matches your existing HSI — installing the wrong voltage will burn the new one out instantly
• Bracket and connector geometry vary by OEM — bring the old part in to match

How do I test a hot surface ignitor?

Pull it out, check resistance with a multimeter across the leads. Healthy HSIs read roughly 40-90 ohms (80V) or 40-200 ohms (120V). Open circuit = dead. Bring it to the counter — we test these free.

Why does my new HSI keep failing?

HSIs fail from cycle stress and contamination. Common causes: dirty filter (overheats furnace, short-cycles), dirty flame sensor (forces re-light attempts), oversized furnace, or skin oils on the ceramic element. Fix the root cause when you replace.

How long should an HSI last?

3-7 years typical. Short-cycling burns through HSIs fast — address what's causing the short-cycling, not just the burned ignitor.