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.

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.

"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.

"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?

"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.

"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.

"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.

"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.

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

"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