How To Troubleshoot A Flame Sensor With A Megohmmeter To Check The Ceramic Insulator

A flame sensor or sparker for heating systems can be bench tested and checked for ceramic continuity with a megohmmeter. The ceramic insulator can become weak, have hair line cracks or just be due to poor quality. Using a megohmmeter to check the ceramic insulator value can help to determine these issues. As per the White-Rodgers premium flame sensor manual, the value must be a minimum of 500 megaohms.
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[@colinyonkman1972]

I was a the shop wondering if I would ever need that tool. Now I need one because, that is an amazing tip to know.
Thank you for sharing your knowledge

[@HVACKnowItAll]

My pleasure, but that tool goes well beyond that test.

[@fixitfelix718]

Thanks just posted a video on my meter and didnt know what microamps were...thanks for your video!!!

[@josebuenfil7559]

Gracias

[@user-pf1kt3cr8p]

Can you use a Supco Megohmmeter M500 to do this test or do I need the ET600? Awesome video. Thank you for sharing your knowledge.

[@cooliosis1862]

I just put the probe on the bracket or where the boot plugs in, put my other probe on the flame rod, move the probe slowly up and down the flame rod, and test continuity. If it shows continuity after you clean it it is good. If it is too chewed from condensate or whatever it will not. All that really matters is the hot junction has continuity. It works for me. The only thing I measure ohms on is the wire for the boot from the board.
Here up north we mostly work on boilers though. I don't know what types of stuff you have going on down south.
Anyways that method works for me

[@HVACKnowItAll]

That's not the same as this test. This is an insualtion test, not a flame rod continuity test.

[@Oz_is_on_fire]

Good one! Didn’t know this before, thanks!

[@HVACKnowItAll]

My pleasure

[@victork3397]

I had a junior tech call me for help because the furnace low volt fuse would blow every time the furnace would light. He unplugged the flame sensor and it lit for a few seconds then shut down, fuse intact. When he put it back and the furnace lit again, the fuse would immediately blow.
That was definitely a oddball one. I suggested replacing flame sensor and bringing a control board just in case the new flame sensor didn’t fix it. Not sure what else it could be 🤷‍♂️ any ideas?

[@jimfurnell7657]

Great tip, didn't know about it 👍

[@HVACKnowItAll]

Thanks Jim!

[@brianmcdermott1718]

Greart tips. Thank you.

[@HVACKnowItAll]

You're welcome!

[@whitesheatingairappliancer7101]

Great video.

[@HVACKnowItAll]

Thank you!

[@mikeymartinez1099]

How do you like that meggar? I’m considering it as an alternative to the fluke option! Thanks!

[@HVACKnowItAll]

It works quite well

[@NotThatGuy_YepThatGuy]

Thanks

[@HVACKnowItAll]

You're welcome

[@LuisRamos-rw5yu]

Could I use supco m500

[@HVACKnowItAll]

Should be fine yes

[@lightningbolt8592]

I like it

[@HVACKnowItAll]

Thanks Nolan!

[@stephwaylonwells3218]

👍

[@HVACKnowItAll]

👍

[@HVACKnowItAll]

Anyone else try this?

[@isaacyoung8029]

I tend to avoid taking them off because of rust. I only do it if they look dirty/broken.