Glow bar igniter

Having trouble with my Fridgidaire oven. Sometimes is just doesn't heat up. Looked up the igniter function referenced in link below.

Don't most resistance heaters increase in resistance as they heat up? Maybe the igniter is not NiChrome.

6-4 "The same thing happens, electrically speaking, with the igniter. When you first apply voltage, the igniter is cold and the resistance is high. When the igniter heats up, the resistance drops, and electricity is able to flow through it more easily, and the voltage across it drops."

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Reply to
Stumpy
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"Stumpy"

** The article mentions that glow bar igniters use "Carborundum".

Carborundum = Silicon Carbide = a semiconductor !!!

Like most semiconductors, it has a NEGATIVE temperature co-efficient.

So, when AC power is applied the igniter heats and draws more and more current as it reaches a yellow glow - the current is then high enough to operate a solenoid valve to turn on the gas.

Whoooop !!

The gas flame also heats the igniter and it stays at a low resistance value till you turn the oven off.

However, the gas flame eats away at the material and after maybe hundreds of hours it becomes damaged and so the resistance goes up - whether it is hot or cold.

When enough damage has occurred, it will no longer pass sufficient AC current to operate the gas valve.

It still gets hot, maybe even yellow hot at some spots - but no whooop cos there is no gas.

.... Phil

Reply to
Phil Allison

I've got a flat, Norton type igniter which may not be carborundum. I thought SiC had a positive temperature co-efficient of resistance. Wasn't on the list I looked up Well I'm not worried, Amazon has an OEM replacement for less than $20. Looks like an easy fix even if I don't understand it. Maybe the packaging will give a description.

Reply to
Stumpy

An invisible crack will render it useless. Before installing, flex your new one to reveal any hairline cracks. They are extremely brittle. So do not do what I just told you to do.

Reply to
Bulkhead

"Stumpy"

** Same type in my Westinghouse oven.

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** It is ABSOLUTELY carborundum !!!!!!!!!

** Silicon Carbide is negative up about 800C, then goes positive.

The resistance of the igniter shown drops by a factor of 2 when heated to red glow.

The advice in the link is all correct.

OTOH - you are an ass.

... Phil

Reply to
Phil Allison

Right - I'll definitely do that.

Reply to
Stumpy

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Uh no, they use silicon nitride now for some ignitors.

Reply to
Cydrome Leader

New one went in fast. Tried flexing the old, heat discolored one. It is very stiff, tough material. Unlikely to break it unless you're trying to.

Reply to
Stumpy

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