our 4 year old boiler has started to intermittently give a no flame
detection fault code. resetting the boiler usually cures it for a day or
two. is this a common problem on these, and is it an easy fix.

"Paul" wrote in message
...
our 4 year old boiler has started to intermittently give a no flame
detection fault code. resetting the boiler usually cures it for a day or
two. is this a common problem on these, and is it an easy fix.


If the boiler has a permanent pilot flame, then make sure it is not being
blown out by the wind coming in the flue / chimney. This happened on ours,
and was cured by a baffle on the outside flue pipe. Pop rivet a small sheet
of galvanized steel around part of the flue to stop the wind from blowing
straight inside.

If the boiler has an electronic ignition, then check all the electrical
connections inside the boiler control panel. Vibration from running fans,
temperature changes Etc. can cause the connector to loosen off from their
mounts. The cold boiler will spark, but if it's hot it wont, sort of
scenario.

It might just be getting old and starting to feel its age. Nothing lasts
for ever, and the old bones will eventually have to give. If you're
confident and competent enough to the testing your self, then go ahead and
check all the things it could be. If you don't feel safe, or have any doubt
about your ability to handle gas connections, then get someone qualified to
check it for you.

I think all of us in the group, wish we could actually see exactly what
posters are talking about in these situations. We could probably diagnose
the problem in a couple of minutes, and fix it in a few hours on most of
them. Ah well, it's not to be. :-)

Good luck with your fix.

Paul wrote:
our 4 year old boiler has started to intermittently give a no flame
detection fault code. resetting the boiler usually cures it for a day
or two. is this a common problem on these, and is it an easy fix.

We had a Worcester Bosch 3-year boiler exhibit a similar fault, except that
after it was off for a while, it would work for an hour at most.

The PCB was changed, the FFD was changed, and the fan pressure sensor was
changed without improvement, although after these were done the boiler
worked long enough for the CH engineer to go to another job each time. The
CH guy eventually found by sheer luck that there was a tiny split in the
rubber hose from the fan unit to the pressure sensor. Of course, it was on
the back of the hose, not visible from the front. Cutting 5 mm off the hose
solved the fault and the boiler has worked perfectly since.

It seems that the split did not affect the working of a cold boiler, but
once it had got up to temperature the split opened enough for the pressure
sensor to assume that the fan wasn't working correctly.

--
Jeff

"BigWallop" wrote in message
om...
If the boiler has an electronic ignition, then check all the electrical
connections inside the boiler control panel. Vibration from running fans,
temperature changes Etc. can cause the connector to loosen off from their
mounts. The cold boiler will spark, but if it's hot it wont, sort of
scenario.





thanks for the replies so far, the boiler has electronic ignition. i have
checked all the connections and they look ok, the only thing i have noticed
is that one of the wires going to the electrodes has a sooty deposit on it
so there may be a short to the case, does the electronic ignition produce
high enough voltages to arc through poor insulation?. looking at the wire
the insulation looks ok

"Paul" wrote in message
...

"BigWallop" wrote in message
om...
If the boiler has an electronic ignition, then check all the electrical
connections inside the boiler control panel. Vibration from running
fans,
temperature changes Etc. can cause the connector to loosen off from
their
mounts. The cold boiler will spark, but if it's hot it wont, sort of
scenario.


thanks for the replies so far, the boiler has electronic ignition. i have
checked all the connections and they look ok, the only thing i have
noticed
is that one of the wires going to the electrodes has a sooty deposit on it
so there may be a short to the case, does the electronic ignition produce
high enough voltages to arc through poor insulation?. looking at the wire
the insulation looks ok


Yes. If the integrity of the insulation has been compromised, then the
spark will not reach the tip and will jump to the closest negative point
along its path. If you have an old BIC pen. Try sliding the case of the
pen over the wire to create a shield where you think the short is occurring.
An old plastic pop bottle can also be cut to make a wrapping for the
insulation. Held in place with a couple of cable ties or something. Don't
use metal ties as it will only give the arc another path to follow.

Where the ignition control wiring runs inside the boiler is not a hot part,
as such, and should be cool enough for a thermal plastic, like the pen case
or plastic bottle, to stay in a working condition for a good long while.

Good luck with your repair.

In message , Paul
writes

"BigWallop" wrote in message
. com...
If the boiler has an electronic ignition, then check all the electrical
connections inside the boiler control panel. Vibration from running fans,
temperature changes Etc. can cause the connector to loosen off from their
mounts. The cold boiler will spark, but if it's hot it wont, sort of
scenario.





thanks for the replies so far, the boiler has electronic ignition. i have
checked all the connections and they look ok, the only thing i have noticed
is that one of the wires going to the electrodes has a sooty deposit on it
so there may be a short to the case, does the electronic ignition produce
high enough voltages to arc through poor insulation?. looking at the wire
the insulation looks ok


does the pcb have a separate HT and flame sense lead ?

The sooty deposit will be because of electrostatic attraction around the
HT - it's a red herring

Q1 has any wiring been changed recently which would lead to the
possibility of live and neutral being arse about face

Q2 do you have bad earthing

Q3 is the sense electrode (if its not the same as the ign electrode) in
the flame

Q4 If the HT lead is used for flame sensing, is it intact ? The fact
that it will conduct a high voltage spark doesn't mean that it will
conduct the small flame sensing current

Q5 do you have a chair to sit down on when they tell you the price of a
new pcb?




--
geoff

In message , BigWallop
writes

"Paul" wrote in message
...

"BigWallop" wrote in message
om...
If the boiler has an electronic ignition, then check all the electrical
connections inside the boiler control panel. Vibration from running
fans,
temperature changes Etc. can cause the connector to loosen off from
their
mounts. The cold boiler will spark, but if it's hot it wont, sort of
scenario.


thanks for the replies so far, the boiler has electronic ignition. i have
checked all the connections and they look ok, the only thing i have
noticed
is that one of the wires going to the electrodes has a sooty deposit on it
so there may be a short to the case, does the electronic ignition produce
high enough voltages to arc through poor insulation?. looking at the wire
the insulation looks ok


Yes. If the integrity of the insulation has been compromised, then the
spark will not reach the tip and will jump to the closest negative point
along its path.

The problem is that it is not flame sensing, not that it isn't sparking
at the electrode

You could maybe paint a Bic pen black with white ends and chant the
magic words "izzy wizzy , lets get busy" while waving it furiously
around, but other than that I really don't think it's going to help

--
geoff

In message , Jeff Layman
writes
Paul wrote:
our 4 year old boiler has started to intermittently give a no flame
detection fault code. resetting the boiler usually cures it for a day
or two. is this a common problem on these, and is it an easy fix.

We had a Worcester Bosch 3-year boiler exhibit a similar fault, except that
after it was off for a while, it would work for an hour at most.

The PCB was changed, the FFD was changed, and the fan pressure sensor was
changed without improvement, although after these were done the boiler
worked long enough for the CH engineer to go to another job each time. The
CH guy eventually found by sheer luck that there was a tiny split in the
rubber hose from the fan unit to the pressure sensor. Of course, it was on
the back of the hose, not visible from the front. Cutting 5 mm off the hose
solved the fault and the boiler has worked perfectly since.

It seems that the split did not affect the working of a cold boiler, but
once it had got up to temperature the split opened enough for the pressure
sensor to assume that the fan wasn't working correctly.

But a split in a tube to the APS has nothing to do whatsoever with flame
sensing

Not a similar fault at all

--
geoff

"geoff" wrote in message
...
In message , Paul
writes



does the pcb have a separate HT and flame sense lead ?

Yes


The sooty deposit will be because of electrostatic attraction around the
HT - it's a red herring

Ah ok


Q1 has any wiring been changed recently which would lead to the
possibility of live and neutral being arse about face

Nothing been touched at all, bolier been working fine for the past four
years


Q2 do you have bad earthing

Not That i am aware of, not touched any wiring recently


Q3 is the sense electrode (if its not the same as the ign electrode) in
the flame

Will check on that, touch wood the boiler has worked ok since.


Q4 If the HT lead is used for flame sensing, is it intact ? The fact that
it will conduct a high voltage spark doesn't mean that it will conduct the
small flame sensing current

will check continuity and resistance of both.


Q5 do you have a chair to sit down on when they tell you the price of a
new pcb?


Hopefully be ok on that, we pay a little extra on the house insurance to
cover boiler breakdowns, we are covered for two hours labour and £100 + vat
in parts, your going to tell me the boards £200 quid now. was hoping the
boiler would pack up altogether before we called the insurance in, i know
how hard finding intermitant faults is.

Paul.

In message , Paul
writes

"geoff" wrote in message
...
In message , Paul
writes



does the pcb have a separate HT and flame sense lead ?

Yes


The sooty deposit will be because of electrostatic attraction around the
HT - it's a red herring

Ah ok


Q1 has any wiring been changed recently which would lead to the
possibility of live and neutral being arse about face

Nothing been touched at all, bolier been working fine for the past four
years


Q2 do you have bad earthing

Not That i am aware of, not touched any wiring recently


Q3 is the sense electrode (if its not the same as the ign electrode) in
the flame

Will check on that, touch wood the boiler has worked ok since.


Q4 If the HT lead is used for flame sensing, is it intact ? The fact that
it will conduct a high voltage spark doesn't mean that it will conduct the
small flame sensing current

will check continuity and resistance of both.


Q5 do you have a chair to sit down on when they tell you the price of a
new pcb?


Hopefully be ok on that, we pay a little extra on the house insurance to
cover boiler breakdowns, we are covered for two hours labour and £100 + vat
in parts, your going to tell me the boards £200 quid now. was hoping the
boiler would pack up altogether before we called the insurance in,

I'm sure that can be arranged ...



i know
how hard finding intermitant faults is.

Paul.



--
geoff

geoff wrote:
In message , Jeff Layman
writes
Paul wrote:
our 4 year old boiler has started to intermittently give a no flame
detection fault code. resetting the boiler usually cures it for a
day or two. is this a common problem on these, and is it an easy
fix.

We had a Worcester Bosch 3-year boiler exhibit a similar fault,
except that after it was off for a while, it would work for an hour
at most. The PCB was changed, the FFD was changed, and the fan pressure
sensor was changed without improvement, although after these were
done the boiler worked long enough for the CH engineer to go to
another job each time. The CH guy eventually found by sheer luck
that there was a tiny split in the rubber hose from the fan unit to
the pressure sensor. Of course, it was on the back of the hose, not
visible from the front. Cutting 5 mm off the hose solved the fault
and the boiler has worked perfectly since. It seems that the split did
not affect the working of a cold boiler,
but once it had got up to temperature the split opened enough for
the pressure sensor to assume that the fan wasn't working correctly.

But a split in a tube to the APS has nothing to do whatsoever with
flame sensing

Not a similar fault at all

Perhaps I should have chosen my wording more carefully. Sometimes when a
fault code appears, it may lead you in the wrong direction.

In my case, the WB showed a flashing lockout light. According to the
fault-point diagram it was Fault E, and if the fault was not a gas supply
problem, it could be rectified by replacing the spark electrode or HT leads,
replacing the PCB, replacing the gas valve or cable, or replacing the flame
sensor or cable. As previously stated, it was none of these. It should have
shown as Fault B, with only the demand light on - that would have included
replacing the APS tube.



--
Jeff

"geoff" wrote in message
...
In message , Paul
writes

snipped


Hopefully be ok on that, we pay a little extra on the house insurance to
cover boiler breakdowns, we are covered for two hours labour and £100 +
vat
in parts, your going to tell me the boards £200 quid now. was hoping the
boiler would pack up altogether before we called the insurance in,

I'm sure that can be arranged ...


I know a guy down the pub, who'll do it for a tenner. :-)





i know
how hard finding intermitant faults is.

Paul.



--
geoff

In message , Jeff Layman
writes
geoff wrote:
In message , Jeff Layman
writes
Paul wrote:
our 4 year old boiler has started to intermittently give a no flame
detection fault code. resetting the boiler usually cures it for a
day or two. is this a common problem on these, and is it an easy
fix.

We had a Worcester Bosch 3-year boiler exhibit a similar fault,
except that after it was off for a while, it would work for an hour
at most. The PCB was changed, the FFD was changed, and the fan pressure
sensor was changed without improvement, although after these were
done the boiler worked long enough for the CH engineer to go to
another job each time. The CH guy eventually found by sheer luck
that there was a tiny split in the rubber hose from the fan unit to
the pressure sensor. Of course, it was on the back of the hose, not
visible from the front. Cutting 5 mm off the hose solved the fault
and the boiler has worked perfectly since. It seems that the split did
not affect the working of a cold boiler,
but once it had got up to temperature the split opened enough for
the pressure sensor to assume that the fan wasn't working correctly.

But a split in a tube to the APS has nothing to do whatsoever with
flame sensing

Not a similar fault at all

Perhaps I should have chosen my wording more carefully. Sometimes when a
fault code appears, it may lead you in the wrong direction.

In my case, the WB showed a flashing lockout light. According to the
fault-point diagram it was Fault E, and if the fault was not a gas supply
problem, it could be rectified by replacing the spark electrode or HT leads,
replacing the PCB, replacing the gas valve or cable, or replacing the flame
sensor or cable. As previously stated, it was none of these. It should have
shown as Fault B, with only the demand light on - that would have included
replacing the APS tube.

Which all goes to show that actually having a clue is better than
following fault codes

If you recognised that your problem was "none of the above" why did you
post it and call it a similar problem ?

It clearly wasn't


--
geoff