A neighbour has this combi boiler out of action with the overheat LED
coming on solid after a few seconds, and no fan spinning.

I deduced fan failure and narrowed it down to a faulty relay on the main
PCB. I've replaced that, and it's now got a running fan, pump, empty
condensate trap - but no ignition, absolutely no attempt at sparks and
no voltage at the gas valve.

Thinking something phutt has gone wrong with part of the PCB that drives
the ignition voltage generator, but then again it could be some
programmed line in the micro yelling 'If adrian is messing about with
me, just be as safe as possible'.

These neighbours haven't washed themselves in hot water for three days
and their dog looks a bit distressed....

I'm thinking I might soon be running in the direction of Geoff for a
recon PCB but is there anything else I've missed?

--
Adrian C

On Jun 2, 8:27*pm, Adrian C wrote:
A neighbour has this combi boiler out of action with the overheat LED
coming on solid after a few seconds, and no fan spinning.

I deduced fan failure and narrowed it down to a faulty relay on the main
PCB. I've replaced that, and it's now got a running fan, pump, empty
condensate trap - but no ignition, absolutely no attempt at sparks and
no voltage at the gas valve.

Thinking something phutt has gone wrong with part of the PCB that drives
the ignition voltage generator, but then again it could be some
programmed line in the micro yelling 'If adrian is messing about with
me, just be as safe as possible'.

These neighbours haven't washed themselves in hot water for three days
and their dog looks a bit distressed....
I'm thinking I might soon be running in the direction of Geoff for a
recon PCB but is there anything else I've missed?

--
Adrian C

Have you checked the air pressure switch?

On 02/06/2011 20:57, chudford wrote:
On Jun 2, 8:27 pm, Adrian wrote:
A neighbour has this combi boiler out of action with the overheat LED
coming on solid after a few seconds, and no fan spinning.

I deduced fan failure and narrowed it down to a faulty relay on the main
PCB. I've replaced that, and it's now got a running fan, pump, empty
condensate trap - but no ignition, absolutely no attempt at sparks and
no voltage at the gas valve.

Thinking something phutt has gone wrong with part of the PCB that drives
the ignition voltage generator, but then again it could be some
programmed line in the micro yelling 'If adrian is messing about with
me, just be as safe as possible'.

These neighbours haven't washed themselves in hot water for three days
and their dog looks a bit distressed....
I'm thinking I might soon be running in the direction of Geoff for a
recon PCB but is there anything else I've missed?

--
Adrian C

Have you checked the air pressure switch?

Yes, but that was with me blowing through the tube. Probably the gust of
the fan is insufficient to activate it? I'll recheck.

--
Adrian C

In message , Adrian C
writes
A neighbour has this combi boiler out of action with the overheat LED
coming on solid after a few seconds, and no fan spinning.

I deduced fan failure and narrowed it down to a faulty relay on the
main PCB. I've replaced that, and it's now got a running fan, pump,
empty condensate trap - but no ignition, absolutely no attempt at
sparks and no voltage at the gas valve.

Thinking something phutt has gone wrong with part of the PCB that
drives the ignition voltage generator, but then again it could be some
programmed line in the micro yelling 'If adrian is messing about with
me, just be as safe as possible'.

These neighbours haven't washed themselves in hot water for three days
and their dog looks a bit distressed....

I'm thinking I might soon be running in the direction of Geoff for a
recon PCB but is there anything else I've missed?

If you have neither gas or spark, then it would point me in the
direction of the air pressure switch not transferring (for whatever
reason - e.g APS failure, blocked pipes or some other blockage) or hall
effect sensor in the fan, depending on which it has, I can't remember


--
geoff

On 02/06/2011 22:05, geoff wrote:

If you have neither gas or spark, then it would point me in the
direction of the air pressure switch not transferring (for whatever
reason - e.g APS failure, blocked pipes or some other blockage) or hall
effect sensor in the fan, depending on which it has, I can't remember



Thanks Geoff,

Yup, looks like the differential pressure sensor is kaput. Shorted it
out it's connections after the fan came on, and the boiler fired up.
This sensor is mounted near the top of the sealed plenum chamber, and
the tiny vent hole for the switch is clear. We did a suck/blow test of
the switch when we removed it, but human breath is not that well
calibrated I suppose.

Probably have to do some more diagnostics after that to get the DHW
supply working after we've fitted the above. Noted that even though the
microswitch from the diverter valve works (and is switching 30V through
the PCB), it doesn't do a DHW startup. I'll scratch my head on that next.

So so far I've got

1) a dead fan relay, presume burned contacts - replaced works
2) a duff pressure sensor, replaced will work
3) something else wrong with DHW, another sensor fail?

That's a combination of calamities, with no one event for blame. Is this
4yr old boiler crap or is it just me? Neighbour tells me it's their second.

--
Adrian C

On Jun 4, 8:58*am, Adrian C wrote:
On 02/06/2011 22:05, geoff wrote:



If you have neither gas or spark, then it would point me in the
direction of the air pressure switch not transferring (for whatever
reason - e.g APS failure, blocked pipes or some other blockage) or hall
effect sensor in the fan, depending on which it has, I can't remember

Thanks Geoff,

Yup, looks like the differential pressure sensor is kaput. Shorted it
out it's connections after the fan came on, and the boiler fired up.
This sensor is mounted near the top of the sealed plenum chamber, and
the tiny vent hole for the switch is clear. We did a suck/blow test of
the switch when we removed it, but human breath is not that well
calibrated I suppose.

Probably have to do some more diagnostics after that to get the DHW
supply working after we've fitted the above. Noted that even though the
microswitch from the diverter valve works (and is switching 30V through
the PCB), it doesn't do a DHW startup. I'll scratch my head on that next.

So so far I've got

1) a dead fan relay, presume burned contacts - replaced works
2) a duff pressure sensor, replaced will work
3) something else wrong with DHW, another sensor fail?

That's a combination of calamities, with no one event for blame. Is this
4yr old boiler crap or is it just me? Neighbour tells me it's their second.

--
Adrian C

My son has one of these and it is forever going wrong.

The DHW failure on his was the diaphram in the diverter valve which
had perished.

You can get replacement diaphrams which are fairly easy to fit.

On Jun 4, 12:57*pm, chudford wrote:
On Jun 4, 8:58*am, Adrian C wrote:





On 02/06/2011 22:05, geoff wrote:

If you have neither gas or spark, then it would point me in the
direction of the air pressure switch not transferring (for whatever
reason - e.g APS failure, blocked pipes or some other blockage) or hall
effect sensor in the fan, depending on which it has, I can't remember

Thanks Geoff,

Yup, looks like the differential pressure sensor is kaput. Shorted it
out it's connections after the fan came on, and the boiler fired up.
This sensor is mounted near the top of the sealed plenum chamber, and
the tiny vent hole for the switch is clear. We did a suck/blow test of
the switch when we removed it, but human breath is not that well
calibrated I suppose.

Probably have to do some more diagnostics after that to get the DHW
supply working after we've fitted the above. Noted that even though the
microswitch from the diverter valve works (and is switching 30V through
the PCB), it doesn't do a DHW startup. I'll scratch my head on that next.

In message , Adrian C
writes
On 02/06/2011 22:05, geoff wrote:

If you have neither gas or spark, then it would point me in the
direction of the air pressure switch not transferring (for whatever
reason - e.g APS failure, blocked pipes or some other blockage) or hall
effect sensor in the fan, depending on which it has, I can't remember



Thanks Geoff,

Yup, looks like the differential pressure sensor is kaput. Shorted it
out it's connections after the fan came on, and the boiler fired up.
This sensor is mounted near the top of the sealed plenum chamber, and
the tiny vent hole for the switch is clear. We did a suck/blow test of
the switch when we removed it, but human breath is not that well
calibrated I suppose.

Probably have to do some more diagnostics after that to get the DHW
supply working after we've fitted the above. Noted that even though the
microswitch from the diverter valve works (and is switching 30V through
the PCB), it doesn't do a DHW startup. I'll scratch my head on that next.

So so far I've got

1) a dead fan relay, presume burned contacts - replaced works
2) a duff pressure sensor, replaced will work
3) something else wrong with DHW, another sensor fail?

Flow switch?
Diverter valve microswitches not feeding back to the pcb - contacts or
plunger operating the microswitches not lifting for whatever reason
(split diaphragm ?) ?



That's a combination of calamities, with no one event for blame. Is
this 4yr old boiler crap or is it just me? Neighbour tells me it's
their second.


--
geoff