Re: [EE]: Flame rectification

Spark now tracks down one of the ceramic electrodes. Will try scotch bright.

I dont think they are in parallel. Keen to short one and test when next
home.

On Sun, 21 Dec. 2025, 05:37 Bob Blick, <[email protected]> wrote:

> Hi Harold,
>
> Thanks for the link to the flame detector patent.
>
> On my gas stove, the ignition switch on one of the knobs doesn't always
> work. So I'll turn that burner on, then turn on another burner. When it
> lights, they'll both light. I forget if the spark electrodes are all
> directly paralleled or if there is a 4-way enclosed spark gap somewhere to
> distribute the ignition. That would make the system more tolerant of
> partial shorts of one or more electrodes.
>
> Friendly regards, Bob
>
>
> ________________________________________
> From: Piclist <[email protected]> on behalf of Harold
> Sent: Friday, December 19, 2025 1:41 PM
> To: Microcontroller discussion list - Public.
> Subject: Re: [EE]: Flame rectification
>
> I was not aware of the use of flame rectification for flame detection. I
> see a patent on it at
>
> https://patentimages.storage.googleapis.com/bd/ad/0d/f76a332c6472e8/US4427363.pdf
> .
>
> I've seen thermocouples used to control the pilot light gas valve in water
> heaters. The patent mentions that thermocouples are slow, so you could end
> up with a lot of gas beind dumped into the room before the loss of flame
> is detected. The flame rectification is quick. Very clever!
>
> We have a gas stove with electronic ignition. One thing that I thought was
> clever is that the igniter causes the spark on all the burners, not just
> the one that is turned on. I think this is a clever design simplification.
> The burner with gas is ignited. The others just spark. I SUSPECT the spark
> gaps are in parallel, so it seems there could be a situation where one
> spark gap "hogs" the current with a lower arc voltage causing the others
> to not arc. One of our burners seems to ignite less reliably, but I don't
> really know why.
>
> We did have an intermittent problem in our gas furnace. The contractor
> finally just replaced the control board. It has a microcontroller, the
> ignition transformer, a bunch of relays, and other stuff. As mentioned
> previously, there is a sequence of operations that it goes through in
> starting. It first starts the exhaust fan and ensures it is working (as
> mentioned previously, I suspect it uses differential pressure). It then
> turns on the pilot gas and the igniter. On detecting the pilot flame, it
> turns on the main gas (accurate sound effect given previously). Then after
> a few seconds (probably temperature controlled), it turns on the blower
> that moves the heated air into the ducts.
>
> There are a LOT of safety features to ensure the house does not blow up or
> burn down. I wonder how many furnaces have caught houses on fire. I
> suspect it's pretty low.
>
> Google AI says "The most common causes of house fires are cooking (the
> leading cause, often from unattended food), followed by heating equipment
> (especially portable heaters), electrical malfunctions (wiring,
> appliances), smoking materials, and candles, with children playing with
> fire and dryers also significant factors, all highlighting risks from
> unattended flames, faulty systems, and flammable materials."
>
> Harold
>
>
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