Gas Boiler simply stopped working - ideas?

[Phillip Brown]

I appreciate it is the bank holiday, but as my house is rather cold, I hope
you can respond before then :) I recently fitted a reconditioned Potterton
Netaheat Fan Unit after the old one gave up the ghost, and it has be running
well until I turned the thermostat down for one night whilst I was away.

When I returned on Sunday, the thermostat had turned itself on as the house
was below 21-degrees, but the boiler wouldn't turn on. Nothing I could do
would make the boiler start up again. I have tried:

Replacing the thermostat
Testing the manual control of the motorised valve
Turning off/on all the switches on the timer
Checking the fuses to the main system and on the boiler's PCB

When the thermostat turns on, the valve opens and the pump starts, however
the boiler just does not ignite. It also does not make the 'humming noise'
that you get for 10 seconds before ignition, which I assume is the fan?

Is it possible the fan could be faulty, or is there some other possibility
between the timer (which works as it too turns the pump and valve on and
off) and the boiler?

Many thanks in advance of your prompt reply.

[John Stumbles]

Phillip Brown wrote:
> I appreciate it is the bank holiday, but as my house is rather cold, I hope
> you can respond before then :) I recently fitted a reconditioned Potterton
> Netaheat Fan Unit after the old one gave up the ghost, and it has be running
> well until I turned the thermostat down for one night whilst I was away.
>
> When I returned on Sunday, the thermostat had turned itself on as the house
> was below 21-degrees, but the boiler wouldn't turn on. Nothing I could do
> would make the boiler start up again. I have tried:
>
> Replacing the thermostat
> Testing the manual control of the motorised valve
> Turning off/on all the switches on the timer
> Checking the fuses to the main system and on the boiler's PCB
>
> When the thermostat turns on, the valve opens and the pump starts, however
> the boiler just does not ignite. It also does not make the 'humming noise'
> that you get for 10 seconds before ignition, which I assume is the fan?

Sounds like it.

> Is it possible the fan could be faulty, or is there some other possibility
> between the timer (which works as it too turns the pump and valve on and
> off) and the boiler?

Is there mains getting to the boiler? Sometimes there is just one mains
cable to the boiler which is made live when there's demand via the
programmer + room 'stat + motorised valve, sometimes there is a live
feed via a fused spur and a separate switched live via prog + stat +
valve. Either way if the live is getting switched on and off with the
room stat + valve (test with a neon screwdriver) but the fan's not
starting it suggests the fan is kaput, but if there's no switched live
you've got an electrical problem.

[Phillip Brown]

"John Stumbles" > wrote in message
...
> Phillip Brown wrote:
>> Is it possible the fan could be faulty, or is there some other
>> possibility between the timer (which works as it too turns the pump and
>> valve on and off) and the boiler?
>
> Is there mains getting to the boiler? Sometimes there is just one mains
> cable to the boiler which is made live when there's demand via the
> programmer + room 'stat + motorised valve, sometimes there is a live feed
> via a fused spur and a separate switched live via prog + stat + valve.
> Either way if the live is getting switched on and off with the room stat +
> valve (test with a neon screwdriver) but the fan's not starting it
> suggests the fan is kaput, but if there's no switched live you've got an
> electrical problem.

Thanks John, there is no other fuse, the cable chain is as follows AFAIK:

Mains box with fuse > Wall thermostat > Timer / Pump / Valve > Boiler

When I turn on the timer with the thermostat up, it starts the valve opening
and pump running. I can see the cable running out of the timer which goes
all the way in to the boiler.

What part of the cable would I prod with a neon screwdriver to check the
live is getting to the boiler?

Could it not be the PCB on the boiler itself?

Thanks again.

[BigWallop]

"Phillip Brown" > wrote in message
. ..
> I appreciate it is the bank holiday, but as my house is rather cold, I
hope
> you can respond before then :) I recently fitted a reconditioned
Potterton
> Netaheat Fan Unit after the old one gave up the ghost, and it has be
running
> well until I turned the thermostat down for one night whilst I was away.
>
> When I returned on Sunday, the thermostat had turned itself on as the
house
> was below 21-degrees, but the boiler wouldn't turn on. Nothing I could do
> would make the boiler start up again. I have tried:
>
> Replacing the thermostat
> Testing the manual control of the motorised valve
> Turning off/on all the switches on the timer
> Checking the fuses to the main system and on the boiler's PCB
>
> When the thermostat turns on, the valve opens and the pump starts, however
> the boiler just does not ignite. It also does not make the 'humming
noise'
> that you get for 10 seconds before ignition, which I assume is the fan?
>
> Is it possible the fan could be faulty, or is there some other possibility
> between the timer (which works as it too turns the pump and valve on and
> off) and the boiler?
>
> Many thanks in advance of your prompt reply.
>
>

If you can't hear the flue fan running in the boiler, then I'd be tempted to
say it is that which is at fault, again. You say the new fan was a
re-conditioned one, but you didn't say what made the old fan go faulty. You
may have fitted the new fan unit to a faulty boiler. What was the symptoms
of the old fan unit failing? Did you get any sort of guarantee with the
re-conditioned fan? Did you test the circuit that supplies the fan from the
boiler?

[Phillip Brown]

"BigWallop" > wrote in message
. ..
> If you can't hear the flue fan running in the boiler, then I'd be tempted
> to
> say it is that which is at fault, again. You say the new fan was a
> re-conditioned one, but you didn't say what made the old fan go faulty.
> You
> may have fitted the new fan unit to a faulty boiler. What was the
> symptoms
> of the old fan unit failing?

It was the original fan, so over a decade old, and was just groaning and
turning very slowly - basically 'old age'. Boiler had been serviced a week
before that by British Gas.

> Did you get any sort of guarantee with the
> re-conditioned fan?

I'd have to check but I'm sure I do. It was from CET Ltd. who seem quite
good.

> Did you test the circuit that supplies the fan from the
> boiler?

Nope, that's the next step I guess. Can you confirm if I simply use a neon
screwdriver on the red/brown cable that goes into the fan to check this?
Then if it is live but the fan is dead, then the fan is... well, dead I
assume. I'm quite clever, me. ;)

[BigWallop]

"Phillip Brown" > wrote in message
...
> "BigWallop" > wrote in message
> . ..
> > If you can't hear the flue fan running in the boiler, then I'd be
tempted
> > to
> > say it is that which is at fault, again. You say the new fan was a
> > re-conditioned one, but you didn't say what made the old fan go faulty.
> > You
> > may have fitted the new fan unit to a faulty boiler. What was the
> > symptoms
> > of the old fan unit failing?
>
> It was the original fan, so over a decade old, and was just groaning and
> turning very slowly - basically 'old age'. Boiler had been serviced a
week
> before that by British Gas.
>
> > Did you get any sort of guarantee with the
> > re-conditioned fan?
>
> I'd have to check but I'm sure I do. It was from CET Ltd. who seem quite
> good.
>
> > Did you test the circuit that supplies the fan from the
> > boiler?
>
> Nope, that's the next step I guess. Can you confirm if I simply use a
neon
> screwdriver on the red/brown cable that goes into the fan to check this?
> Then if it is live but the fan is dead, then the fan is... well, dead I
> assume. I'm quite clever, me. ;)
>
>

The fan is a mains voltage appliance, so a good test to see if the fan is
working properly, is to fit a length of cable to it and plug it in to a
power outlet. If it don't work then, it's dead. This lets you rule out the
fan completely and you can concentrate on the boiler supply side of things.
Once you know that part, get back to us and we'll try to talk you through
other things to test for.

Placing a mains tester screw driver on the connector terminals is not a fair
test I'm afraid. You really need a test meter to make sure you are getting
all the connections you need too, to make the fan and things work properly.
The break in circuit may be on the negative side of the supply, which a
mains tester screw driver won't show.

[John]

"Phillip Brown" > wrote in message
. ..
>I appreciate it is the bank holiday, but as my house is rather cold, I hope
>you can respond before then :) I recently fitted a reconditioned Potterton
>Netaheat Fan Unit after the old one gave up the ghost, and it has be
>running well until I turned the thermostat down for one night whilst I was
>away.
>
> When I returned on Sunday, the thermostat had turned itself on as the
> house was below 21-degrees, but the boiler wouldn't turn on. Nothing I
> could do would make the boiler start up again. I have tried:
>
> Replacing the thermostat

Why? did you by any chance test it and prove it faulty or just make a guess?
Seriously what is your level of technical expertise in tracing a possible
fault?


> Testing the manual control of the motorised valve
> Turning off/on all the switches on the timer
> Checking the fuses to the main system and on the boiler's PCB
>
> When the thermostat turns on, the valve opens and the pump starts, however
> the boiler just does not ignite. It also does not make the 'humming
> noise' that you get for 10 seconds before ignition, which I assume is the
> fan?
>
> Is it possible the fan could be faulty, or is there some other possibility
> between the timer (which works as it too turns the pump and valve on and
> off) and the boiler?
>

I can't recall if this boiler has an overheat thermostat which requires
manually resetting. If it has find it and test it for being open circuit.

[Phillip Brown]

"John" > wrote in message
...
>
> "Phillip Brown" > wrote in message
>> When I returned on Sunday, the thermostat had turned itself on as the
>> house was below 21-degrees, but the boiler wouldn't turn on. Nothing I
>> could do would make the boiler start up again. I have tried:
>>
>> Replacing the thermostat
>
> Why? did you by any chance test it and prove it faulty or just make a
> guess?
> Seriously what is your level of technical expertise in tracing a possible
> fault?

Forgot to mention, the thermostat had been behaving strangely for a week
beforehand. E.g. the required temperature was set at 24-degress, the room
temperature was 25, yet the thermostat had not clicked 'off'. It is a
Drayton Digistat 3 and previous to this worked fine for a year. My logical
conclusion was therefore that the thermostat had given up the ghost and was
failing to turn on my heating system.

>> Testing the manual control of the motorised valve
>> Turning off/on all the switches on the timer
>> Checking the fuses to the main system and on the boiler's PCB
>>
>> When the thermostat turns on, the valve opens and the pump starts,
>> however the boiler just does not ignite. It also does not make the
>> 'humming noise' that you get for 10 seconds before ignition, which I
>> assume is the fan?
>>
>> Is it possible the fan could be faulty, or is there some other
>> possibility between the timer (which works as it too turns the pump and
>> valve on and off) and the boiler?
>
> I can't recall if this boiler has an overheat thermostat which requires
> manually resetting. If it has find it and test it for being open circuit.

Could you point me in the direction of what to look for? I see nothing in
the manual about this.

In the past, when the water ran dry in my system, it did shut itself down,
but seemed to come back on after an hour, of its own accord.

Thanks for the ongoing advice.

[Lurch]

On Mon, 03 Jan 2005 15:43:28 GMT, "Phillip Brown" >
strung together this:

>Forgot to mention, the thermostat had been behaving strangely for a week
>beforehand. E.g. the required temperature was set at 24-degress, the room
>temperature was 25, yet the thermostat had not clicked 'off'.

Christ! How accurate do you want it? I'd call that reasonable, look at
the instructions and you'll see what the olerances are. I'd allow it
to be more than 1degC out. Did you measure the exact temperature on
the exact point on the stat that measures temperature, or did you
think it would measure the temperature on the other side of the room?
--

SJW
Please reply to group or use 'usenet' in email subject

[Phillip Brown]

"Lurch" > wrote in message
...
> On Mon, 03 Jan 2005 15:43:28 GMT, "Phillip Brown" >
> strung together this:
>
>>Forgot to mention, the thermostat had been behaving strangely for a week
>>beforehand. E.g. the required temperature was set at 24-degress, the room
>>temperature was 25, yet the thermostat had not clicked 'off'.
>
> Christ! How accurate do you want it? I'd call that reasonable, look at
> the instructions and you'll see what the olerances are. I'd allow it
> to be more than 1degC out. Did you measure the exact temperature on
> the exact point on the stat that measures temperature, or did you
> think it would measure the temperature on the other side of the room?

Thanks for the compliment however my name's not Christ, but that aside
there's another misunderstanding. Normally I set the stat to 24. When the
temperature display *ON THE STAT* reaches 24, the stat turns itself off --
it knows it has achieved its goal.

Lately however, the display *on the stat* was showing 25+, even though the
desired temperature was set to only 24. It was continuing to heat the house
beyond what it was set to do. This had never happened in over a year I had
it, so I understandably diagnosed a problem with the stat.

I did not measure the actual air temperature separately!

> --
>
> SJW
> Please reply to group or use 'usenet' in email subject

[Lee]

Phillip Brown wrote:

> Lately however, the display *on the stat* was showing 25+, even though the
> desired temperature was set to only 24. It was continuing to heat the house
> beyond what it was set to do. This had never happened in over a year I had
> it, so I understandably diagnosed a problem with the stat.

Ours tends to do this when the batteries need changing...

Lee
--
Email address is valid, but is unlikely to be read.

[John]

"BigWallop" > wrote in message
. ..
>
> "Phillip Brown" > wrote in message
> ...
>> "BigWallop" > wrote in message
>> . ..
>> > If you can't hear the flue fan running in the boiler, then I'd be
> tempted
>> > to
>> > say it is that which is at fault, again. You say the new fan was a
>> > re-conditioned one, but you didn't say what made the old fan go faulty.
>> > You
>> > may have fitted the new fan unit to a faulty boiler. What was the
>> > symptoms
>> > of the old fan unit failing?
>>
>> It was the original fan, so over a decade old, and was just groaning and
>> turning very slowly - basically 'old age'. Boiler had been serviced a
> week
>> before that by British Gas.
>>
>> > Did you get any sort of guarantee with the
>> > re-conditioned fan?
>>
>> I'd have to check but I'm sure I do. It was from CET Ltd. who seem quite
>> good.
>>
>> > Did you test the circuit that supplies the fan from the
>> > boiler?
>>
>> Nope, that's the next step I guess. Can you confirm if I simply use a
> neon
>> screwdriver on the red/brown cable that goes into the fan to check this?
>> Then if it is live but the fan is dead, then the fan is... well, dead I
>> assume. I'm quite clever, me. ;)
>>
>>

Beware if the fan has three connections (high speed, low speed and neutral

>
> The fan is a mains voltage appliance, so a good test to see if the fan is
> working properly, is to fit a length of cable to it and plug it in to a
> power outlet. If it don't work then, it's dead. This lets you rule out
> the
> fan completely and you can concentrate on the boiler supply side of
> things.
> Once you know that part, get back to us and we'll try to talk you through
> other things to test for.

Once more for good luck - beware if it a two speed fan (see above)
>
> Placing a mains tester screw driver on the connector terminals is not a
> fair
> test I'm afraid. You really need a test meter to make sure you are
> getting
> all the connections you need too, to make the fan and things work
> properly.
> The break in circuit may be on the negative side of the supply, which a
> mains tester screw driver won't show.
>
Try "testing" at both sides of the connections. The Neutral should not light
the neon if present. If its not then you will get a light

[Phillip Brown]

"Lee" > wrote in message
...
> Phillip Brown wrote:
>
>> Lately however, the display *on the stat* was showing 25+, even though
>> the desired temperature was set to only 24. It was continuing to heat
>> the house beyond what it was set to do. This had never happened in over
>> a year I had it, so I understandably diagnosed a problem with the stat.
>
> Ours tends to do this when the batteries need changing...

That was my first hunch too, so I changed them but no different. Also the
battery indicator wasn't flashing so they were apparently still good.
Thanks anyway.

[Lurch]

On Mon, 03 Jan 2005 17:15:04 GMT, "Phillip Brown" >
strung together this:

>Lately however, the display *on the stat* was showing 25+, even though the
>desired temperature was set to only 24. It was continuing to heat the house
>beyond what it was set to do. This had never happened in over a year I had
>it, so I understandably diagnosed a problem with the stat.
>
Ah, that would appear to make sense.
--

SJW
Please reply to group or use 'usenet' in email subject

[Toby Sleigh]

"John" > wrote in message
...
>

> I can't recall if this boiler has an overheat thermostat which requires
> manually resetting. If it has find it and test it for being open circuit.
The basic unit does not come with a overheat thermostat. Potterton sell an
add on overheat thermostat kit for sealed systems.

BTW my Potterton Neataheat 16/22 packed up on Boxing day, similar symptoms
except that the fan started then nothing.
Removed control PCB and found a couple of blown tracks. Soldered wire links
across break, no probs since.

Toby

[Phillip Brown]

"Toby Sleigh" > wrote in message
...
>
> "John" > wrote in message
> ...
>>
>> I can't recall if this boiler has an overheat thermostat which requires
>> manually resetting. If it has find it and test it for being open circuit.
> The basic unit does not come with a overheat thermostat. Potterton sell an
> add on overheat thermostat kit for sealed systems.
>
> BTW my Potterton Neataheat 16/22 packed up on Boxing day, similar symptoms
> except that the fan started then nothing.
> Removed control PCB and found a couple of blown tracks. Soldered wire
> links across break, no probs since.
>
> Toby

Must be a special 'break around Christmas time' setting they all have.

My fan isn't turning however, which indicates to me that the PCB is the 2nd
in line, fan being 1st in line. I.e. if the fan doesn't turn, then the PCB
can't be the fault?

[BigWallop]

"Phillip Brown" > wrote in message
k...
> "Toby Sleigh" > wrote in message
> ...
> >
<<<snipped>>>
> > Toby
>
> Must be a special 'break around Christmas time' setting they all have.
>
> My fan isn't turning however, which indicates to me that the PCB is the 2nd
> in line, fan being 1st in line. I.e. if the fan doesn't turn, then the PCB
> can't be the fault?
>
>
How did you test the fan, Philip? Did you actually remove the fan to do the
testing?

[Phillip Brown]

"BigWallop" > wrote in message
k...
>
> "Phillip Brown" > wrote in message
> k...
>> "Toby Sleigh" > wrote in message
>> ...
>> >
> <<<snipped>>>
>> > Toby
>>
>> Must be a special 'break around Christmas time' setting they all have.
>>
>> My fan isn't turning however, which indicates to me that the PCB is the
>> 2nd
>> in line, fan being 1st in line. I.e. if the fan doesn't turn, then the
>> PCB
>> can't be the fault?
>>
> How did you test the fan, Philip? Did you actually remove the fan to do
> the
> testing?
>
Simpler than that, I can't hear it. Normally it hums quite audibly. I'm
pretty sure it's the fan that hums anyway, and now no noise from it.

However tomorrow I will buy a neon screwdriver and test for 230v across the
fan coil. Can people here confirm that is correct and safe?

[Lurch]

On Mon, 03 Jan 2005 22:34:56 GMT, "Phillip Brown" >
strung together this:

>However tomorrow I will buy a neon screwdriver and test for 230v across the
>fan coil. Can people here confirm that is correct and safe?
>
It's not, I can test your fan from here as accurately as you can do it
with a neon screwdriver. You can't test across anything with a neon
screwdriver, you'll strtuggle to test anything reliably.

If you're going to test it buy a decent multimeter. You can get a
suitable one for about £20-30. Alternatively, leave it well alone and
give someone a call.
--

SJW
Please reply to group or use 'usenet' in email subject

[John Stumbles]

Phillip Brown wrote:
> "BigWallop" > wrote in message
> k...
>
>>"Phillip Brown" > wrote in message
k...
>>
>>>"Toby Sleigh" > wrote in message
...
>>>
>><<<snipped>>>
>>
>>>>Toby
>>>
>>>Must be a special 'break around Christmas time' setting they all have.
>>>
>>>My fan isn't turning however, which indicates to me that the PCB is the
>>>2nd
>>>in line, fan being 1st in line. I.e. if the fan doesn't turn, then the
>>>PCB
>>>can't be the fault?
>>>
>>
>>How did you test the fan, Philip? Did you actually remove the fan to do
>>the
>>testing?
>>
>
> Simpler than that, I can't hear it. Normally it hums quite audibly. I'm
> pretty sure it's the fan that hums anyway, and now no noise from it.

(You have checked that the fan's not just jammed by something, haven't you?)


> However tomorrow I will buy a neon screwdriver and test for 230v across the
> fan coil. Can people here confirm that is correct and safe?

Yup, that'll give you a reasonable indication. Make sure you know how to
hold it to get it to light up: there's a little contact on the part of
the screwdriver you hold which you have to be touching for it to light
up when the tip of the 'driver contacts mains (I know this sounds like
an apprentice booby trap but it's not: the current required to make the
neon light up has to go travel through your body to earth, but it's so
minute you can rarely even feel a tingle from it). Check it on parts of
the system you know should be live e.g. the thermostat and programmer,
then check the live terminal where the supply cable enters the boiler.
Check also that the neutral terminal is _not_ live (in case the
connection has come adrift on that side).

WRT Lurch's comment on neon testers and multimeters, note that both
neons and modern digital multimeters have such high input impedances
that they will give unreliable indications on some sorts of faults e.g.
where a connection is basically broken but still capable of passing or
picking up the minute amount of current required to light a neon or
register on a meter. For these situations a simple 2-probe mains tester
with LEDs (or as a DIY alternative a low power mains bulb such as a
fridge or oven bulb or small candle bulb connected to 2 probes) will
give a more reliable indication.

[Phillip Brown]

Just to update the thread, I tested the fan on separate mains and it ran
fine. Turned out the air pressure switch was stuck, which the Potterton
troubleshooting flow chart pointed me to. Cleaning it out resulted in a
working heater. :)

Thanks.

"Phillip Brown" > wrote in message
. ..
>I appreciate it is the bank holiday, but as my house is rather cold, I hope
>you can respond before then :) I recently fitted a reconditioned Potterton
>Netaheat Fan Unit after the old one gave up the ghost, and it has be
>running well until I turned the thermostat down for one night whilst I was
>away.
>
> When I returned on Sunday, the thermostat had turned itself on as the
> house was below 21-degrees, but the boiler wouldn't turn on. Nothing I
> could do would make the boiler start up again. I have tried:
>
> Replacing the thermostat
> Testing the manual control of the motorised valve
> Turning off/on all the switches on the timer
> Checking the fuses to the main system and on the boiler's PCB
>
> When the thermostat turns on, the valve opens and the pump starts, however
> the boiler just does not ignite. It also does not make the 'humming
> noise' that you get for 10 seconds before ignition, which I assume is the
> fan?
>
> Is it possible the fan could be faulty, or is there some other possibility
> between the timer (which works as it too turns the pump and valve on and
> off) and the boiler?
>
> Many thanks in advance of your prompt reply.
>

[John Stumbles]

Phillip Brown wrote:
> Just to update the thread, I tested the fan on separate mains and it ran
> fine. Turned out the air pressure switch was stuck, which the Potterton
> troubleshooting flow chart pointed me to. Cleaning it out resulted in a
> working heater. :)

Are you saying that because the air pressure switch wasn't working the
fan wasn't coming on? That's puzzling me because AIUI on these boilers
the fan runs whenever mains is applied regardless of the air pressure
switch, but the latter has to operate to make the boiler light.

[Phillip Brown]

"John Stumbles" > wrote in message
...
> Phillip Brown wrote:
>> Just to update the thread, I tested the fan on separate mains and it ran
>> fine. Turned out the air pressure switch was stuck, which the Potterton
>> troubleshooting flow chart pointed me to. Cleaning it out resulted in a
>> working heater. :)
>
> Are you saying that because the air pressure switch wasn't working the fan
> wasn't coming on? That's puzzling me because AIUI on these boilers the fan
> runs whenever mains is applied regardless of the air pressure switch, but
> the latter has to operate to make the boiler light.

The fan was off when the air pressure switch was stuck in the wrong
position. I removed the fan from the boiler and tested it separately and it
ran fine. I replaced it, and as soon as the pressure switch was cleaned and
went back to the correct position, the fan started and the boiler ignited.
That's all I can tell you :)

[John]

"John Stumbles" > wrote in message
...
> Phillip Brown wrote:
>> Just to update the thread, I tested the fan on separate mains and it ran
>> fine. Turned out the air pressure switch was stuck, which the Potterton
>> troubleshooting flow chart pointed me to. Cleaning it out resulted in a
>> working heater. :)
>
> Are you saying that because the air pressure switch wasn't working the fan
> wasn't coming on? That's puzzling me because AIUI on these boilers the fan
> runs whenever mains is applied regardless of the air pressure switch, but
> the latter has to operate to make the boiler light.

If the switch has stuck in the fan proved position may boilers will not
begin the ignition cycle.
Its a safety thing:-)

[Paul Barker]

Yes there are on Baxi/Potterton's for instance two levels of checking the pressure switch. Boiler turned on, go check pressure switch to see it is off, then turn on fan then check pressure switch to check it is on. That is to ensure it isn't stuck in the on position.

[raden]

In message >, Phillip
Brown > writes
>
>Must be a special 'break around Christmas time' setting they all have.
>
>My fan isn't turning however, which indicates to me that the PCB is the 2nd
>in line, fan being 1st in line. I.e. if the fan doesn't turn, then the PCB
>can't be the fault?
>
Somebody phoned me up with exactly the same fault on Tuesday, was it you
? (brain dead, I can't remember)

if not ...

If you had a recon netaheat fan from me (CET), then it's very unlikely
that the fan has died. They have new motors on, and I out of over 1000
which have gone out in the last two years, I have had one motor fail.

Assuming that mains is getting to the pcb, it goes to the overheat stat
which, if not short circuit, won't power the fan. If the air pressure
switch has either bad contacts or has welded itself in the wrong
position, the fan won't start either

Really, you need to put mains across the fan motor and see if it runs
directly off the mains. If it does, your problem lies elsewhere, either
the O/h stat, the pcb or the APS.

If you want leading through how to do this, phone me on 01923 229224.
I'm not just there to sell recon stuff, I also try and offer a bit of
support

--
geoff

[raden]

In message >, Phillip
Brown > writes
>>>
>> How did you test the fan, Philip? Did you actually remove the fan to do
>> the
>> testing?
>>
>Simpler than that, I can't hear it. Normally it hums quite audibly. I'm
>pretty sure it's the fan that hums anyway, and now no noise from it.
>
>However tomorrow I will buy a neon screwdriver and test for 230v across the
>fan coil.

Nooooooo!!!

Go and spend a tenner at Maplins and get a multimeter

A neon screwdriver will tell you that there's probably something with
volts on it somewhere within a 100m radius

--
geoff

[raden]

In message >, John Stumbles
> writes
>
>WRT Lurch's comment on neon testers and multimeters, note that both
>neons and modern digital multimeters have such high input impedances
>that they will give unreliable indications on some sorts of faults

Not when set to the correct range and put across 230 volts

Neon screwdrivers are like spurs - only used by cowboys

--
geoff

[raden]

In message >, John Stumbles
> writes
>Phillip Brown wrote:
>> Just to update the thread, I tested the fan on separate mains and it
>>ran fine. Turned out the air pressure switch was stuck, which the
>>Potterton troubleshooting flow chart pointed me to. Cleaning it out
>>resulted in a working heater. :)
>
>Are you saying that because the air pressure switch wasn't working the
>fan wasn't coming on? That's puzzling me because AIUI on these boilers
>the fan runs whenever mains is applied regardless of the air pressure
>switch, but the latter has to operate to make the boiler light.

No, it's a safety feature which also tests the air pressure switch, as
we have seen here. The air pressure switch must be in the normally
closed position and have good ohmic contact.

If the APS had welded itself in the normally open position, in your
understanding, the pcb could light the boiler if the fan wasn't working
--
geoff

[Frank Erskine]

On Thu, 06 Jan 2005 22:50:11 GMT, raden > wrote:

>
>Go and spend a tenner at Maplins and get a multimeter
>
>A neon screwdriver will tell you that there's probably something with
>volts on it somewhere within a 100m radius

Much the same as a nelectronic multimeter...

--
Frank Erskine

[raden]

In message >, Frank Erskine
> writes
>On Thu, 06 Jan 2005 22:50:11 GMT, raden > wrote:
>
>>
>>Go and spend a tenner at Maplins and get a multimeter
>>
>>A neon screwdriver will tell you that there's probably something with
>>volts on it somewhere within a 100m radius
>
>Much the same as a nelectronic multimeter...
>
A nelectronic multimeter?

I expect so

--
geoff

[raden]

In message >, Phillip
Brown > writes
>
>Could it not be the PCB on the boiler itself?
>
Could be

Is there mains across the live and neutral on the pcb ?

.... you can't test this properly with a neon screwdriver - throw it away
and get a multimeter
--
geoff

[raden]

In message >, BigWallop
> writes
>
>>
>
>If you can't hear the flue fan running in the boiler, then I'd be tempted to
>say it is that which is at fault, again. You say the new fan was a
>re-conditioned one, but you didn't say what made the old fan go faulty. You
>may have fitted the new fan unit to a faulty boiler. What was the symptoms
>of the old fan unit failing? Did you get any sort of guarantee with the
>re-conditioned fan? Did you test the circuit that supplies the fan from the
>boiler?
>
And ... was it one of mine ?

If so, as I said in an earlier post, I've (CET) had a ~ 0.1% failure
rate on these fan motors, so it's unlikely

Is there 230 volts across the fan ?

I can always be reached on 01923 229224 if you need walking through
problem solving
--
geoff

[raden]

In message >, Phillip
Brown > writes
>Nope, that's the next step I guess. Can you confirm if I simply use a neon
>screwdriver on the red/brown cable that goes into the fan to check this?
>Then if it is live but the fan is dead, then the fan is... well, dead I
>assume. I'm quite clever, me. ;)
>
CET is on a messianic crusade here

Chuck the screwdriver and get a multimeter

--
geoff