Trusty old Viessmann gave up the ghost yesterday. Flashing fault light.
All my heating info is in the same folder which wasn't with the other
ones. Typical.

I self installed this boiler in the noughties. Had the same thing when it
was near new. Turned out to be the ionization sensor. Eventually bought a
new one, which was a different design.

Not being able to find the service manual, I thought I might as well just
look at it - only two screws to remove it. And it was a bit dirty.

Gave it a good clean with wire wool and boiler is now running again.

But I've ordered up a new one anyway, at about £40 delivered.

Not quite sure how they work? It appears to be just a metal (of some sort)
rod set in a porcelain insulator, and no ground connection.

--
*Am I ambivalent? Well, yes and no.

Dave Plowman London SW
To e-mail, change noise into sound.

On Monday, 10 May 2021 at 15:20:58 UTC+1, Dave Plowman (News) wrote:

Not quite sure how they work? It appears to be just a metal (of some sort)
rod set in a porcelain insulator, and no ground connection.

As I understand it, the flame is full of ions. A small amount of current can flow from the rod to ground through the flame (if it's there).

In article ,
David wrote:
On Monday, 10 May 2021 at 15:20:58 UTC+1, Dave Plowman (News) wrote:

Not quite sure how they work? It appears to be just a metal (of some
sort) rod set in a porcelain insulator, and no ground connection.

As I understand it, the flame is full of ions. A small amount of
current can flow from the rod to ground through the flame (if it's
there).

That would explain the problem with it being dirty. But not why they
changed the design slightly. The original started giving problems when the
boiler was near new. The replacement has done 10 years plus without being
touched.

Having cleaned the old one with wire wool, it's now working normally
again. The new sensor arrived yesterday, so I'll keep it as a spare.

--
*I got a job at a bakery because I kneaded dough.*

Dave Plowman London SW
To e-mail, change noise into sound.

On Wednesday, 12 May 2021 at 14:37:10 UTC+1, Dave Plowman (News) wrote:
In article ,
David wrote:
On Monday, 10 May 2021 at 15:20:58 UTC+1, Dave Plowman (News) wrote:

Not quite sure how they work? It appears to be just a metal (of some
sort) rod set in a porcelain insulator, and no ground connection.

As I understand it, the flame is full of ions. A small amount of
current can flow from the rod to ground through the flame (if it's
there).
That would explain the problem with it being dirty. But not why they
changed the design slightly.

Maybe they just re-sourced the part from somewhere that produced a "close-enough" variant a bit cheaper?