I've probably bored all of you to tears with my ongoing saga over the
Wallstar 15/20 oil boiler, but now I've discovered an interesting
facet of its behaviour.

The lockouts ONLY occur approx 20 to 30 minutes after first switch-on!
AND THEN NEVER HAPPEN AGAIN while there is a "call for heat"!

The Danfoss programmes were set to: 04:30 to 07:30, 16:00 to 17:30 and
21:00 to 22:30.

I have kept a careful record of the boiler lockouts since October.

While reviewing this record (about 12 sheets of A4 by now), it became
obvious that the lockouts only happen (and NOT always) after the
boiler has come on from stone cold.

Here is a summary:

05/Dec/12: Started at 16:00. Locked out at 16:30. Reset pressed. Ran
fine to 17:30
Ditto 06/Dec/12: Started at 16:00. Locked out at 16:20. Reset pressed.
Ran fine to 17:30
Ditto 06/Dec/12: Started at 21:00. Locked out at 21:20. Reset pressed.
Ran fine to 22:30
Ditto 07/Dec/12: Started at 04:30. Locked out at 05:00. Reset pressed.
Ran fine to 07:30
Ditto 08/Dec/12: Started at 16:00. Locked out at 16:25. Reset pressed.
Ran fine to 17:30
Ditto 10/Dec/12: Started at 04:30. Locked out at 04:50. Reset pressed.
Ran fine to 07:30

So yesterday I had the brainwave (well, I thought it was!) of
switching the Danfoss to permanently ON (it's a CP15 and has the
settings ON, OFF, AUTO, ALLDAY), figuring that I'd only need to press
the reset button the once after the first 20 - 30 minutes and
thereafter the boiler would continue to run.

And this is exactly what has happened since yesterday morning at
07:30!

Yesterday morning I switched the Danfoss to ON (i.e. 24/7) and the
boiler started. True to form, it locked out at 07:55, i.e. about 25
minutes later. Then I pressed reset and the boiler has been running
EVER SINCE!

I have adjusted the temperature of the house by use of the Honeywell
TRVs. So right now, at almost ten to seven on Friday morning I have a
lovely warm house and the boiler is still running fine. Not a single
lockout since that first one yesterday morning at 07:55. It's been
running without problem for roughly 23 hours.

Now, which one of you can possibly diagnose why it only locks out
after the boiler starts up the first time from stone cold and comes to
temperature?

Beats me. Beats my heating engineer. Beats even HRM Wallstar, who have
been consulted by my heating engineer several times (he knows several
engineers there personally).

It's a puzzle and no mistake.

MM

On Dec 14, 6:50*am, MM wrote:
I've probably bored all of you to tears with my ongoing saga over the
Wallstar 15/20 oil boiler, but now I've discovered an interesting
facet of its behaviour.

The lockouts ONLY occur approx 20 to 30 minutes after first switch-on!
AND THEN NEVER HAPPEN AGAIN while there is a "call for heat"!

The Danfoss programmes were set to: 04:30 to 07:30, 16:00 to 17:30 and
21:00 to 22:30.

I have kept a careful record of the boiler lockouts since October.

While reviewing this record (about 12 sheets of A4 by now), it became
obvious that the lockouts only happen (and NOT always) after the
boiler has come on from stone cold.

Here is a summary:

05/Dec/12: Started at 16:00. Locked out at 16:30. Reset pressed. Ran
fine to 17:30
Ditto 06/Dec/12: Started at 16:00. Locked out at 16:20. Reset pressed.
Ran fine to 17:30
Ditto 06/Dec/12: Started at 21:00. Locked out at 21:20. Reset pressed.
Ran fine to 22:30
Ditto 07/Dec/12: Started at 04:30. Locked out at 05:00. Reset pressed.
Ran fine to 07:30
Ditto 08/Dec/12: Started at 16:00. Locked out at 16:25. Reset pressed.
Ran fine to 17:30
Ditto 10/Dec/12: Started at 04:30. Locked out at 04:50. Reset pressed.
Ran fine to 07:30

So yesterday I had the brainwave (well, I thought it was!) of
switching the Danfoss to permanently ON (it's a CP15 and has the
settings ON, OFF, AUTO, ALLDAY), figuring that I'd only need to press
the reset button the once after the first 20 - 30 minutes and
thereafter the boiler would continue to run.

And this is exactly what has happened since yesterday morning at
07:30!

Yesterday morning I switched the Danfoss to ON (i.e. 24/7) and the
boiler started. True to form, it locked out at 07:55, i.e. about 25
minutes later. Then I pressed reset and the boiler has been running
EVER SINCE!

I have adjusted the temperature of the house by use of the Honeywell
TRVs. So right now, at almost ten to seven on Friday morning I have a
lovely warm house and the boiler is still running fine. Not a single
lockout since that first one yesterday morning at 07:55. It's been
running without problem for roughly 23 hours.

Now, which one of you can possibly diagnose why it only locks out
after the boiler starts up the first time from stone cold and comes to
temperature?

Beats me. Beats my heating engineer. Beats even HRM Wallstar, who have
been consulted by my heating engineer several times (he knows several
engineers there personally).

It's a puzzle and no mistake.

MM

It might need a new fuel jet?
Bad fuel atomisation leading to marginal conditions/instability of the
flame until the boiler warms through.
Being hot helps the fuel to vapourise better.

Unless the fuel jet has been recently changed.

Is it possible to view the flame and has it's appearance changed?

On 14 Dec, 06:50, MM wrote:
I've probably bored all of you to tears with my ongoing saga over the
Wallstar 15/20 oil boiler, but now I've discovered an interesting
facet of its behaviour.

Snip

Not bored, facinated (though i'm sure you are frustrated!)

How does the boiler now behave (ie how often is it running (I presume
the orange light is now permenantly on?)?
How long is it (the burner) on/off for at a time?

While it's good to be warm, it could be expensive if it keeps firing
for short periods, stopping and firing again.

I think you have said in the past that there isn't a room stat on this
system? I presume there is a cylinder stat on the hot water tank?

Chris

On 14 Dec, 06:50, MM wrote:
I've probably bored all of you to tears with my ongoing saga over the
Wallstar 15/20 oil boiler, but now I've discovered an interesting
facet of its behaviour.

Hmmm.....

Maybe it would be worth having the Engineer wire the boiler correctly
(with a permenant live as well as a "Call for heat" live). and see if
that cures all your problems (Though why this should suddenly be an
issue when it hasn't been during the life of the system so far, I
don't know).

Have Wallstar been advised of the incorrect wiring and asked for their
opinion as to what effect it might have (I did email Wallstar's
technical address myself to ask this question, but didn't get a
reply)?

Chris

On Fri, 14 Dec 2012 00:44:45 -0800 (PST), harry wrote:

It might need a new fuel jet?

Or the wrong one fitted re spray angle and/or fuel rate.

Bad fuel atomisation leading to marginal conditions/instability of the
flame until the boiler warms through.

In half an hour it's going to be more than "warmed through" it it well
hot, which to me indicates possible overheat but that is a seperate
manual reset themostatic trip not a control box lockout. B-(

Half an hour is quite a decent length burn. Pretty much the only thing
that can cause a lockout at that stage is flame failure so (in no
particular order) water in fuel, fuel starvation (anywhere from tank to
jet), wrong/faulty/worn jet, false flame failure detection (dirty/faulty
photocell), intermittent wiring (photocell/oil valve).

'tis a puzzle.

--
Cheers
Dave.

In article ,
MM writes:
I've probably bored all of you to tears with my ongoing saga over the
Wallstar 15/20 oil boiler, but now I've discovered an interesting
facet of its behaviour.

The lockouts ONLY occur approx 20 to 30 minutes after first switch-on!
AND THEN NEVER HAPPEN AGAIN while there is a "call for heat"!

How long does it take to get up to temperature from a cold start?
During the period it's warming up, it will be generating
condensation. I'm not familiar with oil boilers, but with
gas, this normally dries up pretty quickly (except in
condensing boilers). Could it be that some condensation
is running somewhere it shouldn't?

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On Fri, 14 Dec 2012 00:44:45 -0800 (PST), harry
wrote:

It might need a new fuel jet?

Had one at last service in March.

Bad fuel atomisation leading to marginal conditions/instability of the
flame until the boiler warms through.
Being hot helps the fuel to vapourise better.

Unless the fuel jet has been recently changed.

Is it possible to view the flame and has it's appearance changed?

Dunno. Looking at the boiler, which is a very compact design, I'd say
not without any special tool. I'll mention all these points to said
engineer in due course. I'm not going to bother with it any more
before the Christmas week because I'm going away and it looks like the
temperature in this part of the world (Boston area) will stay above
freezing. And I'll leave the heating on low anyway 24/7, since once
it's locked out the first time, it doesn't do so again until the next
time the boiler starts up from stone cold and runs for about 20 to 30
minutes.
http://www.theweatheroutlook.com/for...n,Lincolnshire

MM

On Fri, 14 Dec 2012 09:57:12 +0000 (GMT), "Dave Liquorice"
wrote:

On Fri, 14 Dec 2012 00:44:45 -0800 (PST), harry wrote:

It might need a new fuel jet?

Or the wrong one fitted re spray angle and/or fuel rate.

But why only locking out once in a "call for heat" cycle and always
about 20 to 30 mins after the boiler starts from stone cold?

Bad fuel atomisation leading to marginal conditions/instability of the
flame until the boiler warms through.

In half an hour it's going to be more than "warmed through" it it well
hot, which to me indicates possible overheat but that is a seperate
manual reset themostatic trip not a control box lockout. B-(

Yep, the separate boiler overheat thermostat reset button is inside
the white casing on the INside of the garage. This has never tripped.

Half an hour is quite a decent length burn. Pretty much the only thing
that can cause a lockout at that stage is flame failure so (in no
particular order) water in fuel, fuel starvation (anywhere from tank to
jet), wrong/faulty/worn jet, false flame failure detection (dirty/faulty
photocell), intermittent wiring (photocell/oil valve).

Okay, but yo can set your watch (almost!) by the time to lockout after
starting from stone cold. If any of those were a problem, why would
further lockouts occur? Remember that my test run yesterday till this
morning was 25 hours continuous operation with no lockout apart from
the first one 25 minutes in.

'tis a puzzle.

You're no kidding. HRM have even offered to the engineer to soak test
my boiler on their test rig for a couple of days at their cost (for
good customer relations), but that won't be feasible until the weather
turns milder in March/April.

MM

On Fri, 14 Dec 2012 00:56:09 -0800 (PST), Chris Holmes
wrote:

On 14 Dec, 06:50, MM wrote:
I've probably bored all of you to tears with my ongoing saga over the
Wallstar 15/20 oil boiler, but now I've discovered an interesting
facet of its behaviour.

Snip

Not bored, facinated (though i'm sure you are frustrated!)

Frustration ain't the word for it! What p***es me off is the lack of
decent diagnostic tools. If oil boilers are so temperamental, why
don't they have a USB connection to a PC running a test/diagnostic
program? I worked in the IT industry for many years and if we had
produced such unreliable, undiagnosable kit, we'd have all been fired
(!) years ago.

It's not just Wallstar boilers. My engineer tells me he's been to
Riello boilers, Worcester, Danesmoor, you name it, with similar knotty
problems and it seems to me that the manufacturers just don't place
enough attention on the fact that their ruddy "design marvels" (as
they must think they are) do go wrong and often at the coldest part of
the year. My engineer had 23 emergency calls last week. Bloke must be
working 12 hours a day.

How does the boiler now behave (ie how often is it running (I presume
the orange light is now permenantly on?)?

Yes, the orange light is on as long as the Danfoss is calling for
heat.

The boiler runs constantly as long as the initial lockout is dealt
with by me going outside, removing the cover and pressing the reset
button. Thereafter it doesn't lock out again. Yesterday's test was
over **25** hours, no lockout! (Of course, the boiler itself switches
off and on every 4 - 5 minutes as it comes to temp, then cools down a
bit.)

How long is it (the burner) on/off for at a time?

See (A) or (B) answer below:

(A) If you mean what I referred to in that last sentence, it varies
depending on the setting of the temperature knob on the white casing
INside the garage. This has MAX and MIN positions. When at MAX, the
boiler OFF period is only about 2 minutes. When at MIN it can be off
for up to 10 minutes. I've just completed another hour's test on hot
water only (manual override button), and jotted down the on/off times
as the boiler came to heat, then cooled down etc: ON 14:41, OFF 15:08,
ON 15:12, OFF 15:13, ON 15:18, OFF 15:20, ON 15:26, OFF 15:28, ON
15:36, OFF 15:37. Then it didn't come on again as the one hour call
for heat period had expired by then.

NB: During that last one-hour test it did NOT lock out after 20 - 30
minutes. It didn't lock out at all. As I've said elsewhere, the
lockouts ~mostly~ happen, but not always.

How do I check the on/off times so accurately? Well, I have a Thomy
wireless baby monitor next to the boiler and the parent unit is placed
where I happen to be in the house (kitchen, computer room etc). It's
easy to tell the difference between the comparative roar of the boiler
when it starts and the almost complete silence when it stops.

(B) If, however, you meant how long is it off between calls for heat,
the Danfoss programmes are currently set to: ON 05:30, OFF 07:30, ON
16:00, OFF 17:30, ON 21:00, OFF 22:30. The same settings are used for
Monday through Sunday.

By the way, as I type this, I have to keep breaking off to turn to my
scratchpad and jot down the latest ON or OFF time as I listen to the
parent unit! If I don't get an ON within the expected period, I know
it will have locked out. Then I pop outside, press the reset button
and it then continues to run with no further lockout.

While it's good to be warm, it could be expensive if it keeps firing
for short periods, stopping and firing again.

I'm not really all that worried about the cost right now. Preventing
the pipes from freezing when I'm not here for several days is far more
important to me. Also, I don't have any of the oil-filled electric
rads on, so I'm saving a fair bit on leccy. (Normally, I use the
heating minimally and use the oil-filled standalone rads to heat just
the room(s) I occupy.)

Now the house is indeed nice and warm and it IS a bit of a luxury,
but, paraphrasing that old line from Terry Christian's The Word ("I'll
do anything to get on TV..."), I'll do anything to stop the pipes from
freezing!

The "Firing Rate" stated in the boiler handbook is 1.9 to 2.35 litres
per hour, depending on output in kW (16 to 18).

I think you have said in the past that there isn't a room stat on this
system? I presume there is a cylinder stat on the hot water tank?

Correct. There is no room stat, only the Honeywell TRVs, except on the
towel rad in the bathroom, which my builder said must never be
switched off. There is a Danfoss stat on the hot water tank that is
set to 60 deg C. But note that the cylinder will only be warm-ish most
of the day/night as I only heat enough hot water for a bath or washing
up (or both!). The boiler is mainly used for CH.

MM

On Fri, 14 Dec 2012 01:05:53 -0800 (PST), Chris Holmes
wrote:

On 14 Dec, 06:50, MM wrote:
I've probably bored all of you to tears with my ongoing saga over the
Wallstar 15/20 oil boiler, but now I've discovered an interesting
facet of its behaviour.

Hmmm.....

Maybe it would be worth having the Engineer wire the boiler correctly
(with a permenant live as well as a "Call for heat" live). and see if
that cures all your problems (Though why this should suddenly be an
issue when it hasn't been during the life of the system so far, I
don't know).

Have Wallstar been advised of the incorrect wiring and asked for their
opinion as to what effect it might have (I did email Wallstar's
technical address myself to ask this question, but didn't get a
reply)?

All I know is that the engineer has had close contact with several of
the Wallstar engineers and has consulted them several times over the
past few weeks, which is how long the problem has existed.

As for getting anything out of Wallstar as a *householder*,
fuggeddaboudit! I sent them a *lengthy* email some weeks ago,
detailing my problem. Never got a reply. Not even an acknowledgement.
Nevertheless, you may know from my other posts in e.g. uk.legal that I
don't take these kinds of things lying down, which is why I am keeping
a careful record of the boiler's behaviour. This is for the New Year,
however.

MM

On Fri, 14 Dec 2012 10:39:56 +0000 (UTC),
(Andrew Gabriel) wrote:

In article ,
MM writes:
I've probably bored all of you to tears with my ongoing saga over the
Wallstar 15/20 oil boiler, but now I've discovered an interesting
facet of its behaviour.

The lockouts ONLY occur approx 20 to 30 minutes after first switch-on!
AND THEN NEVER HAPPEN AGAIN while there is a "call for heat"!

How long does it take to get up to temperature from a cold start?

Heating: Approximately 20 to 30 minutes. This is when the lockout, if
it's going to happen, happens. (It doesn't *always* happen!) What I
mean is, the boiler comes to temperature, switches off, waits a few
minutes while the temperature falls, and then is supposed to come back
on. It's at that point that the lockout occurs. When it occurs (and
I've stood many a time in front of the boiler with the cover removed
listening intently) there is NO SIGN of anything happening whatsoever.
No click, no initial fan, nothing, zilch. The red light on the control
box just comes on = locked out!

Hot water: The coming to temp is usually much quicker, say about 10
minutes.

During the period it's warming up, it will be generating
condensation. I'm not familiar with oil boilers, but with
gas, this normally dries up pretty quickly (except in
condensing boilers). Could it be that some condensation
is running somewhere it shouldn't?

Now that could indeed be something else to put to the engineer! I'll
note this down. Thanks! There just has to be something magic about
that 20 to 30 minutes figure.

MM

In article ,
MM writes:
On Fri, 14 Dec 2012 10:39:56 +0000 (UTC),
(Andrew Gabriel) wrote:

In article ,
MM writes:
I've probably bored all of you to tears with my ongoing saga over the
Wallstar 15/20 oil boiler, but now I've discovered an interesting
facet of its behaviour.

The lockouts ONLY occur approx 20 to 30 minutes after first switch-on!
AND THEN NEVER HAPPEN AGAIN while there is a "call for heat"!

How long does it take to get up to temperature from a cold start?

Heating: Approximately 20 to 30 minutes. This is when the lockout, if
it's going to happen, happens. (It doesn't *always* happen!) What I
mean is, the boiler comes to temperature, switches off, waits a few
minutes while the temperature falls, and then is supposed to come back
on. It's at that point that the lockout occurs. When it occurs (and

Ah, at first re-ignition after the cold firing.

I've stood many a time in front of the boiler with the cover removed
listening intently) there is NO SIGN of anything happening whatsoever.
No click, no initial fan, nothing, zilch. The red light on the control
box just comes on = locked out!

Hot water: The coming to temp is usually much quicker, say about 10
minutes.

During the period it's warming up, it will be generating
condensation. I'm not familiar with oil boilers, but with
gas, this normally dries up pretty quickly (except in
condensing boilers). Could it be that some condensation
is running somewhere it shouldn't?

Now that could indeed be something else to put to the engineer! I'll
note this down. Thanks! There just has to be something magic about
that 20 to 30 minutes figure.

So thinking miles ahead with insufficient evidence to back it up...

Is there a flame detection electrode (might also be the ignition
electrode)? If the support/insulation for it is getting wet from
any cold firing condensation, it will conduct to earth when there's
no flame. This can't be detected whilst the flame is on (as the
flame does the same thing), but the control unit will probably
check for no flame before trying to light up, to make sure the
flame detection electrode is working and not shorted to earth.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On 14/12/2012 06:50, MM wrote:
I've probably bored all of you to tears with my ongoing saga over the
Wallstar 15/20 oil boiler, but now I've discovered an interesting
facet of its behaviour.

The lockouts ONLY occur approx 20 to 30 minutes after first switch-on!
AND THEN NEVER HAPPEN AGAIN while there is a "call for heat"!

If the boiler runs continuously for the first 20 -30 min I would say
that that is quite a long burn.

If say you reduced the temperature, the initial burn might be shorter.

My guess is some sort of oil feed problem. Is the tank above or below
the burner?


--
Michael Chare

On Fri, 14 Dec 2012 20:42:14 +0000 (UTC),
(Andrew Gabriel) wrote:

In article ,
MM writes:
On Fri, 14 Dec 2012 10:39:56 +0000 (UTC),
(Andrew Gabriel) wrote:

In article ,
MM writes:
I've probably bored all of you to tears with my ongoing saga over the
Wallstar 15/20 oil boiler, but now I've discovered an interesting
facet of its behaviour.

The lockouts ONLY occur approx 20 to 30 minutes after first switch-on!
AND THEN NEVER HAPPEN AGAIN while there is a "call for heat"!

How long does it take to get up to temperature from a cold start?

Heating: Approximately 20 to 30 minutes. This is when the lockout, if
it's going to happen, happens. (It doesn't *always* happen!) What I
mean is, the boiler comes to temperature, switches off, waits a few
minutes while the temperature falls, and then is supposed to come back
on. It's at that point that the lockout occurs. When it occurs (and

Ah, at first re-ignition after the cold firing.

First *attempt* to re-ignite after the cold firing, coming to temp and
switching off, yes.


I've stood many a time in front of the boiler with the cover removed
listening intently) there is NO SIGN of anything happening whatsoever.
No click, no initial fan, nothing, zilch. The red light on the control
box just comes on = locked out!

Hot water: The coming to temp is usually much quicker, say about 10
minutes.

During the period it's warming up, it will be generating
condensation. I'm not familiar with oil boilers, but with
gas, this normally dries up pretty quickly (except in
condensing boilers). Could it be that some condensation
is running somewhere it shouldn't?

Now that could indeed be something else to put to the engineer! I'll
note this down. Thanks! There just has to be something magic about
that 20 to 30 minutes figure.

So thinking miles ahead with insufficient evidence to back it up...

Is there a flame detection electrode (might also be the ignition
electrode)? If the support/insulation for it is getting wet from
any cold firing condensation, it will conduct to earth when there's
no flame. This can't be detected whilst the flame is on (as the
flame does the same thing), but the control unit will probably
check for no flame before trying to light up, to make sure the
flame detection electrode is working and not shorted to earth.

Okay, that sounds like another excellent point to raise, and logically
sound. I don't myself know whether there is such a device in my
boiler. I know there is a photocell, because I have kept the old parts
and I'm looking at it right now.

If you look at page 38 in
http://www.wallstar.co.uk/content/pdfs/wallstar.pdf there is a
detailed exploded view of the Sterling burner with all the parts
identified.

Further observation since yesterday: It doesn't ~appear~ to lock out
IF the boiler was NOT stone cold on initial start-up! That is, I
allowed a heating cycle to proceed, say, for 2 hour. Then after the
Danfoss had switched off, I waited half an hour and repeated the
exercise. It did not lock out again. It seems that as long as the
boiler DID NOT start from stone cold, the problem of lockout is
avoided.

Of course, in normal use, whehn the Danfoss is set to AUTO and calls
for heat according to the three set programmes, then the boiler is
going to be stone cold every time the next programme starts. At least,
it will with my settings because there is a 8.5 hour gap from the
first to the second and a 3.5 hour gap from the second to the third.

This question of condensation (and throwing it open to everybody in
the thread), is it a recognised ~general~ problem with these types of
oil boiler?

Thanks for your feedback.

MM

On Fri, 14 Dec 2012 23:59:13 +0000, Michael Chare
mUNDERSCOREnews@chareDOTorgDOTuk wrote:

On 14/12/2012 06:50, MM wrote:
I've probably bored all of you to tears with my ongoing saga over the
Wallstar 15/20 oil boiler, but now I've discovered an interesting
facet of its behaviour.

The lockouts ONLY occur approx 20 to 30 minutes after first switch-on!
AND THEN NEVER HAPPEN AGAIN while there is a "call for heat"!

If the boiler runs continuously for the first 20 -30 min I would say
that that is quite a long burn.

If say you reduced the temperature, the initial burn might be shorter.

My guess is some sort of oil feed problem. Is the tank above or below
the burner?

The tank is below the boiler exactly as per the Wallstar installation
instructions.

If there was an oil feed problem, why only in the circumstances I
described? Why not at all during the 25-hour test run on
Thursday/Friday, after the initial lockout and reset?

I have tried setting the temperature control knob on the white casing
inside the garage to MIN, to MAX and to mid-way between MIN and MAX,
and although this does alter the burn and rest (that's rest, not
reset!) times, it makes no difference to that initial lockout when the
boiler started up from stone cold.

MM

In article ,
MM writes:
If you look at page 38 in
http://www.wallstar.co.uk/content/pdfs/wallstar.pdf there is a
detailed exploded view of the Sterling burner with all the parts
identified.

Looking at that, the electrodes are not obviously (to me anyway)
in the right position to double up as a flame failure detector,
but I have no experience of oil burners.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On Sat, 15 Dec 2012 13:48:51 +0000 (UTC), Andrew Gabriel wrote:

If you look at page 38 in
http://www.wallstar.co.uk/content/pdfs/wallstar.pdf there is a
detailed exploded view of the Sterling burner with all the parts
identified.

Looking at that, the electrodes are not obviously (to me anyway)
in the right position to double up as a flame failure detector,
but I have no experience of oil burners.

Oil burners normally use optical means of flame detection. A sooted up
photocell is a common failure mode but easy to sort out.

--
Cheers
Dave.