On Sep 18, 11:04*pm, geoff wrote:
In message
,
harry writes
On Sep 9, 2:05 pm, "Tim Downie" wrote:
My old White Knight gas tumble dryer played up the other day and I found
that the earth electrode (immediately above the main electrode) had eroded
and sagged until it was touching the central electrode. I bent it back and
all was well (briefly - but that's another story).
I thought I ought to order a new electrode but White Knight tell me that my
type (with integral earth electrode) has been superceded by one without an
earth electrode.
I'm sceptical that this will work in my machine (in the absence of an earth)
but I could be wrong.
Here's what mine looks like.
http://www.zen31010.zen.co.uk/images/ffe.jpg
The replacement is just the same but without the "hockey stick" earth
electrode.
I'm waiting to hear from the technical adviser at the moment.
Should I just try it or is my scepticism justified?
Tim
There will be two electrodes. *One is for the spark ignitor. The other
is for detecting the flame. It does this by measuring the resistance
(the flame has low resistance compared with air.)
Good job I got back in time ...
No Harry, stick to your solar panels, you are completely wrong
It ABSOLUTELY doesn't measure the resistance, a flame acts like a lossy
rectifier and the flame sense circuit is looking for that rectification
effect in the flame - its a very safe way of flame detection since it
depends on a parameter that can't easily be duplicated in the way that a
resistance can
As long as the jet from which the gas issues is well earthed, then there
is a circuit when there is a flame (assuming that the sense electrode is
also in the flame)
It's possible one electrode is used for both purposes. Or the two
electrodes may be identicle.
But this isn't the case, is it? he said so
If it's old, it may have a different flame sensor which is a
thermocouple device.
No - he's shown the old one as a single electrode, not a junction
You can tell if it has this, there is a pilot
light.
Eejit
--
geoff- Hide quoted text -
- Show quoted text -
I wish you'd just **** off. I was repairing and running industrial
gas equipment for forty years.
http://en.wikipedia.org/wiki/Auto_reignition
http://en.wikipedia.org/wiki/Flame_d...lame_detection