Andrew Gabriel wrote:
In article ,
"Tim Downie" writes:
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type (with integral earth electrode) has been superceded by one without an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

Looks exactly like the ignition electrode in my Keston boiler.
They failed as the earth electrode drooped and the gap became too big
(it's mounted up the other way in the boiler's downward pointing burner).
They then modified them, and so far, the new type has been OK (I can't
remember what changed - I think the ceramic sleeve became longer, but
it still has the two electrodes).

I did repair the old ones a couple of times by bending the electrode
back, but this has to be done with it hot - if you try bending it cold
after it's had lots of heat treatment in the boiler, it's brittle and
usually snaps.

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?

Usually, the contact gap is resonably critical for proper ignition;
too small or big reduces chance of successful ignition (and too big
can also damage the spark coil). So it depends what the ground
electrode will be and how far away it is.

It's not an ignition electrode, it's for flame sensing (hence subject!).

Tim