Understanding Furnace Flame Proving Controls 

best break down I ever seen or heard. the big picture down to mico picture. darn good.

A microamp is a millionth of an amp 10 ( -6). Milliamp is one-thousandth of an amp. 10 ( -3 ) . Thanks for the lecture, my Goodman furnace had a dirty flame proving sensor. It, ( and the wifie) are both happy now. Oh yea, a billionth of an amp is a nanoamp 10 ( -9). I actually sat through this lecture twice, thanx. KB4ZUS.

I’m a U.K. based gas/heating engineer. You call them furnaces we call them boilers, our boilers are connected (for the most part) to wet radiator heating systems. For a period of my career I worked for a boiler manufacturer, we had a reoccurring fault at a customers property where the boiler would randomly shut down to ignition lock out. Various engineers had visited the property and changed gas valves, ignition leads, flame sensing leads, flame sensing probes and a control board but the problem remained. It was discovered on my visit, that the customer had an intermittent fault with the house electrical system. One of the lighting circuits would put a short to the lighting earth (ground), when that happened it would interrupt the flame rectification circuit on the boiler, problem solved. Good, informative video.

This is absolutely fantastic material. If most of this was taught at all in school it was only a brief glance. Thank you for such a good focus on this and giving an easy way to start implementing in normal checkups. Please bring back this speaker!

Thank you for this explanation. I see someone already commented on the fact that a microamp is a millionth of an amp, not a "billionth" of an amp but let me also add that the actual peak voltage of 120VAC as measured on a True RMS voltmeter is 169.7 Volts at the peak of the sine wave. So pointing to the peak of the sine wave and calling it 120 volts may be leaving out an important concept. I enjoyed your class.

You are a fantastic teacher. I was listening while my husband was watching and I understood a lot of what you were saying. I'm not an HVAC tech. I'm a middle school teacher. I liked your analogies. It made what you were trying to teach a lot easier to understand.

Great talk. Clear and informative. I wish all instructors had this level of knowledge and interest in their topics.

Weird ass analogy with the shot gun and the pellets ngl 🤣 but I guess I got the point

Very great info! Only little snafu was milli-one thousandth and micro-one millionth vs one millionth and one billionth

i love the video but i do have a issue with one part ,water is not a conductor pure h2o is actually an insulator its the other products in water that makes a conductor but love the video ton of knowledge to share thank you

i'm stunned .one word WOW!

This was a great lesson, ty for sharing

Great video well explanation about flame rectification polarity and how to be a better service tech

Enjoyed the lecture, just to raise a point, as far as I am aware Ionization is the reason electricity can be conducted through a flame.

Phenomenal. Great talk and great information. Thank you!

Awesome class.

Great video, my only question is in the given example of the boss kicking the furnace fix the bad ground?

This is a Gem! Great information.

Not knowing anything about HVAC I am totally lost. I have heard mention of the neg. feedback, but it really did not make any sense, well kind of. My AC/furnace was shut down a few years ago. Every year they came out and replaced 2 to 4 lbs of freon and the cap and the control switch, first year $300 second year $400 Third year I replaced the cap and control switch They put the freon on in and it was $500 And the next year I bought window units. But when the temp hit a high of 14% I tried to start up the heat. Cleaned the filters and attempted to clean the ignitor and heat sensor. But broke it and got a new one and got it installed. Still no heat. I cleaned the jets and that was a pain. All it does is run long enough to glow red then shut off if you look close for a brief moment you will see the ignitor have a blue flame around it. Looks more like the old type pilot light being lit. But it soon shuts off and it restarts again. Not sure what to do.

Love it. Thank you.

very good informative video, thanks

I would describe it as the 30 millivolts generated by heating the thermocouple that energizes a coil and thus creating magnetic field strong enough to hold the contact closed

谢谢 真是受益匪浅‘

For that grounding story (too much raining from June to August at that year), could you please let us know the machines' symptoms in that story (48:54-50:05)? I just mean, when that public grounding was not sitting properly, what were the problems with those families' appliances for the users? You are a great teacher, I've watched this video again and again, I've learned much from it. Thank you!

Great video, info. Thanks Well done.

is it a fact that the 120 volts sinewave goes up to 170 volts and down to - 170 ( 1.41 is the square root of 2) and that 220 volts peaks at 311 volts? it's that the 110 and the 220 are RMS volts, NOT peak volts; careful, the peak volts are the ones that shock you !!! now back to the video; an excellent video by the way!!! thanks

Great video as always. I was checking the flame sensor signal on a mid efficiency furnace. When furnace fires up the microamp was around 1.7uA. But within a couple minutes the reading started to drop from 1.7uA to 0.6uA and furnace shuts off. I've checked all grounding, changed flame rod, verified gas pressure, cleaned burners, checked all connections and wires, checked rod distance from burner. The board is sending around 110vac to rod. Can it be a bad board? Thank

Water, which is made of hydrogen and oxygen, is not conductive of electricity. (( 27:55 ))

Yeah I've found ohms testing on ignitors to be very unreliable, I don't even do it anymore. I can tell by the brightness if they're getting hot enough.

If you replace every part that could go bad you'll be putting a new furnace in at every call !

A microamp is a millionth of an amp. A milliamp is a thousant of an amp.

I’m pretty confused, is the flame a conductor inside the Flame rod? Or is the flame touching the orifice which is the ground? Or is the flame touching the heat exchanger metal and that’s the ground? Or is the tip of the flame sensor Arcing to the closest piece of metal inside the furnace?

I really do not like analogies for electrical processes. I like to cover basic electrical principles and then just use that to explain the process. Why is that so difficult? That shotgun analogy was so incredibly useless compared to the actual explanation using electrical vernacular.

Fire the person running the camera. Focus on the slide. Just zoom out please!!!

. Flame is out of control.

@ 36:20, you said "if you get hit by 5 amps, a heavy load, it would knock you across the floor, it hurts"...lol...God help you if you got hit by 5 amps because it could take less than about 1% of that to stop your heart and kill you. Due to the resistance of your body however, it would take a very high voltage (that math you also show) to allow that 5 amps to pass through your body, that's where the puddle of water comes in. Also, mA are thousandths of an amp and uA are millionths of an amp, not millionths and billionths as stated @ 36:32 thru 36:38. But otherwise, good info and thank you for providing it.

There is so much wrong with this presentation, it’s mind boggling.