Flame sensing electrodes
 

Anyone know how these work and why my tumble dryer has a long central
electrode in the flame path with an adjacent earth pin that is angled so
that theres a small gap between the end of the insulated electrode and the
end of the earth pin.

I ask as all the replacement ones I see for sale only have a single
insulated electrode and no earth one. Im assuming that the electronics
for these must be a bit different and a single electrode type wont work in
mine.

Its a White Knight gas tumble dryer. Only 30 years old now so Id like to
get a few more years out of it but Crosslee dont stock spares for this
machine any more and I havent seen anything similar on line.

The present earth pin has suffered some erosion/corrosion and its not
always sensing the flame.

Hopefully, heres a picture. https://photos.app.goo.gl/HGzbwdk6Lw1zMNAb9

Tim

--
Please don't feed the trolls

Flame sensing electrodes
 

On 13/03/2020 17:40, Tim+ wrote:
Anyone know how these work and why my tumble dryer has a long central
electrode in the flame path with an adjacent earth pin that is angled so
that theres a small gap between the end of the insulated electrode and the
end of the earth pin.

Thermocouple for flame detection.

Is the other electrode an earth pin or the electrode for the spark and
is actually connected to a HV generating circuit.



--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

Flame sensing electrodes
 

On 13/03/2020 18:53, alan_m wrote:
On 13/03/2020 17:40, Tim+ wrote:
Anyone know how these work and why my tumble dryer has a long central
electrode in the flame path with an adjacent earth pin thatÂ* is angled so
that theres a small gap between the end of the insulated electrode
and the
end of the earth pin.

Thermocouple for flame detection.

Is the other electrode an earth pin or the electrode for the spark and
is actually connected to a HV generating circuit.




Sorry I missed the photo - which looks like a spark electrode to me
rather than a flame sensor.

--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

Flame sensing electrodes
 

alan_m wrote:
On 13/03/2020 17:40, Tim+ wrote:
Anyone know how these work and why my tumble dryer has a long central
electrode in the flame path with an adjacent earth pin that is angled so
that theres a small gap between the end of the insulated electrode and the
end of the earth pin.

Thermocouple for flame detection.

Um no. Its electronic.

Is the other electrode an earth pin or the electrode for the spark and
is actually connected to a HV generating circuit.

Its definitely NOT an ignition electrode, thats handled by a separate
electrode next to the burner.

Having said that, if it looks like an ignition electrode, maybe Ill have
more luck searching for one of those that I can repurpose.

The machine is working again after cleaning and regapping the electrode. I
think the main problem is that the earth electrode has eroded so much, it
tends to sag in the heat and close up the gap. When it gets too small, it
doesnt seem to detect the flame any more.

Tim


--
Please don't feed the trolls

Flame sensing electrodes
 

Flame sensing is employed in quite a few boilers and heating appliances. There's a pretty good description of the principles in Wikipedia so I'll refrain from repeating it here.

Flame sensing electrodes
 

Cynic wrote:
Flame sensing is employed in quite a few boilers and heating appliances.
There's a pretty good description of the principles in Wikipedia so I'll
refrain from repeating it here.


Yeah, I had seen that but it doesnt really explain why mine has an earth
electrode and none of the new ones do.

Tim

--
Please don't feed the trolls

Flame sensing electrodes
 

Chris Hogg explained on 13/03/2020 :
Looks like a spark ignition electrode, but if you're sure it's the
ignition detector, then within a flame there's some ionisation

I thought ionisation detection was a more recent method than as long
ago as 30 years? The common method back then was the thermocouple
method of flame detection.

Flame sensing electrodes
 

Harry Bloomfield, Esq. wrote:
Chris Hogg explained on 13/03/2020 :
Looks like a spark ignition electrode, but if you're sure it's the
ignition detector, then within a flame there's some ionisation

I thought ionisation detection was a more recent method than as long
ago as 30 years? The common method back then was the thermocouple
method of flame detection.


Fecking hell. How many time do I have to say that its NOT a thermocouple?
Ive owned and serviced this machine for 30 years now. I DO know the
difference.

Year of manufacture.

https://photos.app.goo.gl/jA8HLZCgbJos84ZF8

Annotated wiring diagram

https://photos.app.goo.gl/pptJcPpJdxyBgbEk9

Tim

--
Please don't feed the trolls

Flame sensing electrodes
 

Yeah, I had seen that but it doesnt really explain why mine has an earthÂ*
electrode and none of the new ones do.Â*

Without being there to actually see it I recall there were a few burners that employed the same electrode as both ignition (arc) electrode and flame sense electrode. I can see the earth electrode having a purpose in positioning one end of the ignition arc. For the newer models it may be that reality proved that refinement unnecessary.

Flame sensing electrodes
 

Ignore my previous reply about shared duty electrodes. I hadn't looked at your wiring diagram.

Flame sensing electrodes
 

On Friday, 13 March 2020 19:09:50 UTC, Tim+ wrote:
alan_m wrote:
On 13/03/2020 17:40, Tim+ wrote:
Anyone know how these work and why my tumble dryer has a long central
electrode in the flame path with an adjacent earth pin that is angled so
that theres a small gap between the end of the insulated electrode and the
end of the earth pin.

Thermocouple for flame detection.

Um no. Its electronic.

Is the other electrode an earth pin or the electrode for the spark and
is actually connected to a HV generating circuit.

Its definitely NOT an ignition electrode, thats handled by a separate
electrode next to the burner.

Having said that, if it looks like an ignition electrode, maybe Ill have
more luck searching for one of those that I can repurpose.

The machine is working again after cleaning and regapping the electrode. I
think the main problem is that the earth electrode has eroded so much, it
tends to sag in the heat and close up the gap. When it gets too small, it
doesnt seem to detect the flame any more.

Tim

What's your difficulty with adding more metal to that one?


NT

Flame sensing electrodes
 

This appliance redefines the term old to me. I cannot help but wonder what
else might be happening in the unit. Gas, electricity, water and textiles
and a flame, what could possibly go wrong!

Brian

--
----- --
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"Chris Hogg" wrote in message
...
On 13 Mar 2020 17:40:16 GMT, Tim+ wrote:

Anyone know how these work and why my tumble dryer has a long central
electrode in the flame path with an adjacent earth pin that is angled so
that there's a small gap between the end of the insulated electrode and
the
end of the earth pin.

I ask as all the replacement ones I see for sale only have a single
insulated electrode and no earth one. I'm assuming that the electronics
for these must be a bit different and a single electrode type won't work
in
mine.

It's a White Knight gas tumble dryer. Only 30 years old now so I'd like to
get a few more years out of it but Crosslee don't stock spares for this
machine any more and I haven't seen anything similar on line.

The present earth pin has suffered some erosion/corrosion and it's not
always sensing the flame.

Hopefully, here's a picture. https://photos.app.goo.gl/HGzbwdk6Lw1zMNAb9

Tim

Looks like a spark ignition electrode, but if you're sure it's the
ignition detector, then within a flame there's some ionisation, so
there will be conductivity across the gap when the flame is present.
Like you, I looked at images and only saw single electrode ones, but
presumably the other electrode is just any bit of earthed metal such
as the casing. Your bent electrode is effectively earthed in the same
way. Have you tried cleaning it up with a wire brush or emery paper,
both at the tip and around the base where it clamps onto the frame, to
make a good electrical contact there?

--

Chris

Flame sensing electrodes
 

On Friday, 13 March 2020 17:40:19 UTC, Tim+ wrote:
Anyone know how these work and why my tumble dryer has a long central
electrode in the flame path with an adjacent earth pin that is angled so
that theres a small gap between the end of the insulated electrode and the
end of the earth pin.

I ask as all the replacement ones I see for sale only have a single
insulated electrode and no earth one. Im assuming that the electronics
for these must be a bit different and a single electrode type wont work in
mine.

Its a White Knight gas tumble dryer. Only 30 years old now so Id like to
get a few more years out of it but Crosslee dont stock spares for this
machine any more and I havent seen anything similar on line.

The present earth pin has suffered some erosion/corrosion and its not
always sensing the flame.

Hopefully, heres a picture. https://photos.app.goo.gl/HGzbwdk6Lw1zMNAb9


The resistance path in a flame is very low.
The probe is measuring the absence or not of the flame by measuring resistance.

Quite often the probe is just a an ordinary spark electrode used for this purpose.

Flame sensing electrodes
 

Tim+ submitted this idea :
Fecking hell. How many time do I have to say that its NOT a thermocouple?
Ive owned and serviced this machine for 30 years now. I DO know the
difference.

Comments like that will deter people from helping you!

At 30 years, you have maybe had your monies worth out of it. Is the
probe damaged or broken, if not then perhaps the electronics have
failed.

Flame sensing electrodes
 

On 14/03/2020 07:51, harry wrote:
On Friday, 13 March 2020 17:40:19 UTC, Tim+ wrote:
Anyone know how these work and why my tumble dryer has a long central
electrode in the flame path with an adjacent earth pin that is angled so
that theres a small gap between the end of the insulated electrode and the
end of the earth pin.

I ask as all the replacement ones I see for sale only have a single
insulated electrode and no earth one. Im assuming that the electronics
for these must be a bit different and a single electrode type wont work in
mine.

Its a White Knight gas tumble dryer. Only 30 years old now so Id like to
get a few more years out of it but Crosslee dont stock spares for this
machine any more and I havent seen anything similar on line.

The present earth pin has suffered some erosion/corrosion and its not
always sensing the flame.

Hopefully, heres a picture. https://photos.app.goo.gl/HGzbwdk6Lw1zMNAb9


The resistance path in a flame is very low.
The probe is measuring the absence or not of the flame by measuring resistance.

Quite often the probe is just a an ordinary spark electrode used for this purpose.


The key thing about a flame sensing electrode+flame is that it acts as a
diode and will only conduct current in one direction.
If it conducted in both directions it wouldn't be possible to discern
between a normal "flame present" or a "flame missing and the electrodes
shorted"

Flame sensing electrodes
 

On Saturday, 14 March 2020 08:50:43 UTC, wrote:
Tim+ submitted this idea :
Fecking hell. How many time do I have to say that its NOT a thermocouple?
Ive owned and serviced this machine for 30 years now. I DO know the
difference.

Comments like that will deter people from helping you!

At 30 years, you have maybe had your monies worth out of it. Is the
probe damaged or broken, if not then perhaps the electronics have
failed.

I suspect the op knows more about this than you realise.

Flame sensing electrodes
 

Harry Bloomfield, Esq. wrote:
Tim+ submitted this idea :
Fecking hell. How many time do I have to say that its NOT a thermocouple?
Ive owned and serviced this machine for 30 years now. I DO know the
difference.

Comments like that will deter people from helping you!

At 30 years, you have maybe had your monies worth out of it. Is the
probe damaged or broken, if not then perhaps the electronics have
failed.


Well thats probably true but I do get very frustrated when I offer FACTS
about a machine Ive owned for 30 years and yet folk insist on offering
fiction about an appliance theyre clearly not familiar with.

Tim

--
Please don't feed the trolls

Flame sensing electrodes
 

On Saturday, 14 March 2020 10:00:22 UTC, John Kenyon wrote:
On 14/03/2020 07:51, harry wrote:
On Friday, 13 March 2020 17:40:19 UTC, Tim+ wrote:
Anyone know how these work and why my tumble dryer has a long central
electrode in the flame path with an adjacent earth pin that is angled so
that theres a small gap between the end of the insulated electrode and the
end of the earth pin.

I ask as all the replacement ones I see for sale only have a single
insulated electrode and no earth one. Im assuming that the electronics
for these must be a bit different and a single electrode type wont work in
mine.

Its a White Knight gas tumble dryer. Only 30 years old now so Id like to
get a few more years out of it but Crosslee dont stock spares for this
machine any more and I havent seen anything similar on line.

The present earth pin has suffered some erosion/corrosion and its not
always sensing the flame.

Hopefully, heres a picture. https://photos.app.goo.gl/HGzbwdk6Lw1zMNAb9


The resistance path in a flame is very low.
The probe is measuring the absence or not of the flame by measuring resistance.

Quite often the probe is just a an ordinary spark electrode used for this purpose.


The key thing about a flame sensing electrode+flame is that it acts as a
diode and will only conduct current in one direction.
If it conducted in both directions it wouldn't be possible to discern
between a normal "flame present" or a "flame missing and the electrodes
shorted"


The gap at the electrode is large, unlikely to bridge with crap.

Flame sensing electrodes
 

On 14/03/2020 11:49, Tim+ wrote:
Harry Bloomfield, Esq. wrote:
Tim+ submitted this idea :
Fecking hell. How many time do I have to say that its NOT a thermocouple?
Ive owned and serviced this machine for 30 years now. I DO know the
difference.

Comments like that will deter people from helping you!

At 30 years, you have maybe had your monies worth out of it. Is the
probe damaged or broken, if not then perhaps the electronics have
failed.


Well thats probably true but I do get very frustrated when I offer FACTS
about a machine Ive owned for 30 years and yet folk insist on offering
fiction about an appliance theyre clearly not familiar with.

Tim

I feel the same about people who have never been to where I live telling
me what its like and how its populations are..


--
"The most difficult subjects can be explained to the most slow witted
man if he has not formed any idea of them already; but the simplest
thing cannot be made clear to the most intelligent man if he is firmly
persuaded that he knows already, without a shadow of doubt, what is laid
before him."

- Leo Tolstoy

Flame sensing electrodes
 

John Kenyon wrote:
On 14/03/2020 07:51, harry wrote:
On Friday, 13 March 2020 17:40:19 UTC, Tim+ wrote:
Anyone know how these work and why my tumble dryer has a long central
electrode in the flame path with an adjacent earth pin that is angled so
that theres a small gap between the end of the insulated electrode and the
end of the earth pin.

I ask as all the replacement ones I see for sale only have a single
insulated electrode and no earth one. Im assuming that the electronics
for these must be a bit different and a single electrode type wont work in
mine.

Its a White Knight gas tumble dryer. Only 30 years old now so Id like to
get a few more years out of it but Crosslee dont stock spares for this
machine any more and I havent seen anything similar on line.

The present earth pin has suffered some erosion/corrosion and its not
always sensing the flame.

Hopefully, heres a picture. https://photos.app.goo.gl/HGzbwdk6Lw1zMNAb9


The resistance path in a flame is very low.
The probe is measuring the absence or not of the flame by measuring resistance.

Quite often the probe is just a an ordinary spark electrode used for this purpose.


The key thing about a flame sensing electrode+flame is that it acts as a
diode and will only conduct current in one direction.
If it conducted in both directions it wouldn't be possible to discern
between a normal "flame present" or a "flame missing and the electrodes
shorted"


How close does the gap need to be to the flame for this effect to work? The
electrodes are several inches from the burner. I cant view the burner in
operation though to confirm how far the flame extends. I dont think its
far though.

Tim

--
Please don't feed the trolls

Flame sensing electrodes
 

On Saturday, 14 March 2020 13:44:13 UTC, Tim+ wrote:
John Kenyon wrote:
On 14/03/2020 07:51, harry wrote:
On Friday, 13 March 2020 17:40:19 UTC, Tim+ wrote:
Anyone know how these work and why my tumble dryer has a long central
electrode in the flame path with an adjacent earth pin that is angled so
that theres a small gap between the end of the insulated electrode and the
end of the earth pin.

I ask as all the replacement ones I see for sale only have a single
insulated electrode and no earth one. Im assuming that the electronics
for these must be a bit different and a single electrode type wont work in
mine.

Its a White Knight gas tumble dryer. Only 30 years old now so Id like to
get a few more years out of it but Crosslee dont stock spares for this
machine any more and I havent seen anything similar on line.

The present earth pin has suffered some erosion/corrosion and its not
always sensing the flame.

Hopefully, heres a picture. https://photos.app.goo.gl/HGzbwdk6Lw1zMNAb9


The resistance path in a flame is very low.
The probe is measuring the absence or not of the flame by measuring resistance.

Quite often the probe is just a an ordinary spark electrode used for this purpose.


The key thing about a flame sensing electrode+flame is that it acts as a
diode and will only conduct current in one direction.
If it conducted in both directions it wouldn't be possible to discern
between a normal "flame present" or a "flame missing and the electrodes
shorted"


How close does the gap need to be to the flame for this effect to work? The
electrodes are several inches from the burner. I cant view the burner in
operation though to confirm how far the flame extends. I dont think its
far though.

It has to be in the flame. Obviously.

They are usually found in blown gas burners (commercial/industrial)

Flame sensing electrodes
 

Virtually nothing for the past 30 years. Its not a Hotpoint!

Its well designed and the construction makes it simple and easy to
service. I can pull out the burner assembly, the motor and the fan with
nothing more than a single cross headed screwdriver in under 10 minutes.
The logic controls for ignition, ignition failure and overheat conditions
make it very €œfail safe€�. It has two gas solenoids in series making the
potential for gas escape in the event of a leaking solenoid exceedingly
remote.

Im very happy using it at night or when out of he house. Dont think Id
feel the same about an electric one.

Tim

Brian Gaff \(Sofa 2\) wrote:
This appliance redefines the term old to me. I cannot help but wonder what
else might be happening in the unit. Gas, electricity, water and textiles
and a flame, what could possibly go wrong!

Brian




--
Please don't feed the trolls

Flame sensing electrodes
 

harry wrote:
On Saturday, 14 March 2020 13:44:13 UTC, Tim+ wrote:
John Kenyon wrote:
On 14/03/2020 07:51, harry wrote:
On Friday, 13 March 2020 17:40:19 UTC, Tim+ wrote:
Anyone know how these work and why my tumble dryer has a long central
electrode in the flame path with an adjacent earth pin that is angled so
that theres a small gap between the end of the insulated electrode and the
end of the earth pin.

I ask as all the replacement ones I see for sale only have a single
insulated electrode and no earth one. Im assuming that the electronics
for these must be a bit different and a single electrode type wont work in
mine.

Its a White Knight gas tumble dryer. Only 30 years old now so Id like to
get a few more years out of it but Crosslee dont stock spares for this
machine any more and I havent seen anything similar on line.

The present earth pin has suffered some erosion/corrosion and its not
always sensing the flame.

Hopefully, heres a picture. https://photos.app.goo.gl/HGzbwdk6Lw1zMNAb9


The resistance path in a flame is very low.
The probe is measuring the absence or not of the flame by measuring resistance.

Quite often the probe is just a an ordinary spark electrode used for this purpose.


The key thing about a flame sensing electrode+flame is that it acts as a
diode and will only conduct current in one direction.
If it conducted in both directions it wouldn't be possible to discern
between a normal "flame present" or a "flame missing and the electrodes
shorted"


How close does the gap need to be to the flame for this effect to work? The
electrodes are several inches from the burner. I cant view the burner in
operation though to confirm how far the flame extends. I dont think its
far though.

It has to be in the flame. Obviously.

They are usually found in blown gas burners (commercial/industrial)


Well in that case I suspect its not using the diode properties. Im pretty
sure its well out of the flame.

I think when it next plays up Ill just make a new earth point next to the
tip of the present electrode and dispense with the eroded one, possibly
just a long slim nut and bolt through the burner casing.

Tim



--
Please don't feed the trolls

Flame sensing electrodes
 

Tim+ has brought this to us :
How close does the gap need to be to the flame for this effect to work? The
electrodes are several inches from the burner. I cant view the burner in
operation though to confirm how far the flame extends. I dont think its
far though.

It has to be actually in the flame, to detect ionisation.

Flame sensing electrodes
 

Tim+ was thinking very hard :
Well in that case I suspect its not using the diode properties. Im pretty
sure its well out of the flame.

Are your certain you are not confusing the ignition electrode with the
flame detection one? The ignition one does not need to be in the flame,
only in the unlit gas. The ionisation electrode tend to wear more
rapidly the the ignition ones.

Flame sensing electrodes
 

Harry Bloomfield, Esq. wrote:
Tim+ was thinking very hard :
Well in that case I suspect its not using the diode properties. Im pretty
sure its well out of the flame.

Are your certain you are not confusing the ignition electrode with the
flame detection one?

Absolutely. I have the service manual. Parts are clearly labelled.

Tim

--
Please don't feed the trolls

Flame sensing electrodes
 

On 13/03/2020 20:49, Harry Bloomfield wrote:
Chris Hogg explained on 13/03/2020 :
Looks like a spark ignition electrode, but if you're sure it's the
ignition detector, then within a flame there's some ionisation

I thought ionisation detection was a more recent method than as long ago
as 30 years? The common method back then was the thermocouple method of
flame detection.

No - my 30-year-old Baxi Solo boiler uses flame ionisation to detect
when the pilot is lit, and then operate a relay to turn on the main burner.
--
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Roger
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Please reply to Newsgroup. Whilst email address is valid, it is seldom
checked.

Flame sensing electrodes
 

On 14/03/2020 12:48, harry wrote:
On Saturday, 14 March 2020 10:00:22 UTC, John Kenyon wrote:
On 14/03/2020 07:51, harry wrote:
On Friday, 13 March 2020 17:40:19 UTC, Tim+ wrote:
Anyone know how these work and why my tumble dryer has a long central
electrode in the flame path with an adjacent earth pin that is angled so
that theres a small gap between the end of the insulated electrode and the
end of the earth pin.

I ask as all the replacement ones I see for sale only have a single
insulated electrode and no earth one. Im assuming that the electronics
for these must be a bit different and a single electrode type wont work in
mine.

Its a White Knight gas tumble dryer. Only 30 years old now so Id like to
get a few more years out of it but Crosslee dont stock spares for this
machine any more and I havent seen anything similar on line.

The present earth pin has suffered some erosion/corrosion and its not
always sensing the flame.

Hopefully, heres a picture. https://photos.app.goo.gl/HGzbwdk6Lw1zMNAb9


The resistance path in a flame is very low.
The probe is measuring the absence or not of the flame by measuring resistance.

Quite often the probe is just a an ordinary spark electrode used for this purpose.


The key thing about a flame sensing electrode+flame is that it acts as a
diode and will only conduct current in one direction.
If it conducted in both directions it wouldn't be possible to discern
between a normal "flame present" or a "flame missing and the electrodes
shorted"


The gap at the electrode is large, unlikely to bridge with crap.


"Unlikely" does not mean "impossible" - it is still one of the failure
modes which, which if not detected or interpreted incorrectly could lead
to an unsafe condition.,
(along with crap coating the electrode insulation with a resistive
coating, and corrosion leading one electrode coming into contact with
its counterpart.)