Re: [EE]: Flame rectification

Thwe complexity of he control of gas furnaces is a good indicator of why
electric heating is prefferable
__________________________________________
David C Brown
43 Bings Road
Whaley Bridge
High Peak                           Phone: 01663 780582
Derbyshire                eMail: [email protected]
*SK23 7ND          web: www.bings-knowle.co.uk/dcb
<http://www.jb.man.ac.uk/~dcb> *



*Sent from my etch-a-sketch*


On Fri, 19 Dec 2025 at 20:14, Brooke <[email protected]> wrote:

> Hi Bob:
>
> I think this is the same system used on my gas stove cook top.
> PS sometimes there's a problem of not enough spark to light a burner.  Any
> ideas of why?
>
> --
> Have Fun,
>
> Brooke Clarke
> https://www.PRC68.com
> axioms:
> 1. The extent to which you can fix or improve something will be limited by
> how well you understand how it works.
> 2. Everybody, with no exceptions, holds false beliefs.
>
> -------- Original Message --------
> > Date: Fri, 19 Dec 2025 06:37:01 +0000
> > From: Bob Blick<[email protected]>
> > To: "Microcontroller discussion list - Public."<[email protected]>
> > Subject: [EE]: Flame rectification
> > Message-ID:
> >       <
> DS5PR19MB997170D9166D3299975BFE43BDDCA9A@DS5PR19MB997170.namprd19.prod.outlook.com
> >
> >
> > Content-Type: text/plain; charset="iso-8859-1"
> >
> > I was doing a cleaning of my gas-fired forced air furnace, and it got me
> thinking about how wonderfully designed it must be. It has a Honeywell
> S8610U "Intermittent Pilot" module that combines both high(15KV-ish)
> voltage ignition and low(80VAC-ish) voltage, low(5uA-ish) current flame
> detection on the same wire and electrode. Fantastic. Especially since this
> very module has been running since 1997, with very little maintenance, and
> has not missed a beat.
> >
> > Has anyone reverse engineered the in and outs of this device and can
> describe the circuitry, and how flame detection doesn't die the first time
> the high voltage comes on? And how it can toggle between the two modes so
> quickly and reliably?
> >
> > For those who haven't encountered it, the module runs on 24VAC,
> generates a recurring high voltage spark at twelve Hz, energizes a pilot
> gas valve, senses the pilot ignition on the same wire using flame
> rectification (in between the high voltage sparks) and energizes the main
> gas valve if there is a pilot flame present, then stops the HV and
> continues to monitor the flame. It sounds like bzz-click-bzz-thunk-whoosh
> when starting. Quite obsolete by today's standards, of course. It was built
> to last almost forever :)
> >
> > Thanks! Bob
>
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