768A-843 – HOT SURFACE IGNITOR (80V)

White-Rodgers (Copeland) 768A-series silicon nitride hot surface ignitor, published by the manufacturer as an 80 V nitride OEM direct replacement in the Thermo Products group. Nitride ignitors use a silicon-nitrogen probe that glows to ignite the burner gas and are more durable than carbide elements. Pair only with a control board whose ignitor output is 80 V.

Specifications published by the manufacturer. Source: manufacturer documentation.

Specs

• BrandWhite-Rodgers / Copeland
• TypeSilicon nitride hot surface ignitor
• Voltage80 V
• OEM group (per manufacturer)Thermo Products
• ElementSilicon nitride (Si3N4)
• ImportantMust be matched to an 80 V ignitor output board
• Bracket / lead lengthNot published for this specific number

Cross-reference numbers

This part replaces the following OEM and aftermarket numbers:

• 768A-143
• 380650

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

How do I test a hot surface ignitor?

Kill power, unplug it at the connector, and ohm across the two pins. Good readings run roughly 40 to 200 ohms depending on type, with silicon carbide up near the top of that range and silicon nitride lower. OL or infinity means the element is open and the part is done. A reading in range does not fully clear it, because a cracked ignitor can still glow and still fail to light gas, but an open reading is a confirmed bad part before you spend a dime.

Silicon carbide or silicon nitride - which one do I need?

Match your furnace. Silicon carbide is the older flat or forked element with a speckled gray look, and it is brittle enough that people crack them just getting them out of the burner box. Silicon nitride is the newer smooth rod or bar, tougher, and it heats faster. Some run 120 volt and some run 80 volt, and those are not interchangeable. If you cross over to a universal, the bracket has to hold the element in the same spot in the gas stream or it will not light reliably.

Why did my new ignitor only last one season?

Usually one of two things. Either it got handled by the element, or the furnace is short cycling. Never touch the glowing section with bare fingers, because skin oil bakes in and makes a hot spot that cracks the element early. And if you are on your third ignitor in two winters, the ignitor is a symptom - look at flame sensing, a restricted flue, a plugged filter, or limit trips.