My Glowworm micron 60FF runs fine from cold but once the system is
warmed up (but not fully up to temperature) it keeps going around the
cycle: turn on, fan starts, gas ignites, runs about 10 seconds, turns
off, waits 10-30 seconds, repeats. This is all with the central
heating thermostat still calling for heat.

So, is this indicative of a failing themistor? In other words is it
indicating that the boiler water temperature is hot enough and hence
not allowing the boiler to run? The boiler stat is turned full on.

Also, when it is running it does a good impression of a steam engine
..... chuff .... chuff .... chuff.

In an earlier contribution to this discussion,
Honeymonster wrote:

My Glowworm micron 60FF runs fine from cold but once the system is
warmed up (but not fully up to temperature) it keeps going around the
cycle: turn on, fan starts, gas ignites, runs about 10 seconds, turns
off, waits 10-30 seconds, repeats. This is all with the central
heating thermostat still calling for heat.

So, is this indicative of a failing themistor? In other words is it
indicating that the boiler water temperature is hot enough and hence
not allowing the boiler to run? The boiler stat is turned full on.

Also, when it is running it does a good impression of a steam engine
.... chuff .... chuff .... chuff.


Do you any means (e.g. IR thermometer) of measuring the *actual* flow
temperature when it starts cycling? What evidence do you have that it's not
"up to temperature"?
--
Cheers,
Roger
______
Please reply to newsgroup.
Reply address IS valid, but is disposable in the event of excessive
spam.

"Honeymonster" wrote in message
oups.com...
My Glowworm micron 60FF runs fine from cold but once the system is
warmed up (but not fully up to temperature) it keeps going around the
cycle: turn on, fan starts, gas ignites, runs about 10 seconds, turns
off, waits 10-30 seconds, repeats. This is all with the central
heating thermostat still calling for heat.

So, is this indicative of a failing themistor? In other words is it
indicating that the boiler water temperature is hot enough and hence
not allowing the boiler to run? The boiler stat is turned full on.

Also, when it is running it does a good impression of a steam engine
.... chuff .... chuff .... chuff.


================
Buy a couple of these: http://www.plumbworld.co.uk/0000-118?eid=0023-000001

I think they're also stocked by Wickes, B&Q etc.

They're reasonably accurate and if one is placed on flow and another on
return they will show the difference between flow and return temperatures
which is probably more significant than a maximum temperature.

The manual suggests that the '....chuff ....chuff ....chuff ' ( technically
'hunting' ) is a sign that the circuit board needs to be replaced.

Cic.

In message , Cicero
writes

"Honeymonster" wrote in message
roups.com...
My Glowworm micron 60FF runs fine from cold but once the system is
warmed up (but not fully up to temperature) it keeps going around the
cycle: turn on, fan starts, gas ignites, runs about 10 seconds, turns
off, waits 10-30 seconds, repeats. This is all with the central
heating thermostat still calling for heat.

So, is this indicative of a failing themistor? In other words is it
indicating that the boiler water temperature is hot enough and hence
not allowing the boiler to run? The boiler stat is turned full on.

Also, when it is running it does a good impression of a steam engine
.... chuff .... chuff .... chuff.


================
Buy a couple of these: http://www.plumbworld.co.uk/0000-118?eid=0023-000001

I think they're also stocked by Wickes, B&Q etc.

They're reasonably accurate and if one is placed on flow and another on
return they will show the difference between flow and return temperatures
which is probably more significant than a maximum temperature.

The manual suggests that the '....chuff ....chuff ....chuff ' ( technically
'hunting' ) is a sign that the circuit board needs to be replaced.

Micron pcbs are now second only to Suprimas for us now.

The capacitors dry out and connectors fall off


--
geoff

"Honeymonster" wrote in message
oups.com...
My Glowworm micron 60FF runs fine from cold but once the system is
warmed up (but not fully up to temperature) it keeps going around the
cycle: turn on, fan starts, gas ignites, runs about 10 seconds, turns
off, waits 10-30 seconds, repeats. This is all with the central
heating thermostat still calling for heat.

So, is this indicative of a failing themistor? In other words is it
indicating that the boiler water temperature is hot enough and hence
not allowing the boiler to run? The boiler stat is turned full on.

Also, when it is running it does a good impression of a steam engine
.... chuff .... chuff .... chuff.


What colour are the LEDs when on (reset & burner) - orange? If so, replace
PCB. I must have changed 100s of these! The new ones have green LEDs.
Look on the underside of the PCB, there'll be a scorch mark on it.

Someone calls up with a Micron misbehaving, I turn up with my toolbox and a
PCB.

Angus

In message , Fentoozler
writes
"Honeymonster" wrote in message
roups.com...
My Glowworm micron 60FF runs fine from cold but once the system is
warmed up (but not fully up to temperature) it keeps going around the
cycle: turn on, fan starts, gas ignites, runs about 10 seconds, turns
off, waits 10-30 seconds, repeats. This is all with the central
heating thermostat still calling for heat.

So, is this indicative of a failing themistor? In other words is it
indicating that the boiler water temperature is hot enough and hence
not allowing the boiler to run? The boiler stat is turned full on.

Also, when it is running it does a good impression of a steam engine
.... chuff .... chuff .... chuff.


What colour are the LEDs when on (reset & burner) - orange? If so, replace
PCB. I must have changed 100s of these! The new ones have green LEDs.
Look on the underside of the PCB, there'll be a scorch mark on it.

Someone calls up with a Micron misbehaving, I turn up with my toolbox and a
PCB.

Yup - the original ones (6 neons) were crap, the later ones (two green
LEDs), however seem to be not that much better from what I'm seeing
coming in for repair

--
geoff

"raden" wrote in message
...
In message , Fentoozler
writes
"Honeymonster" wrote in message
groups.com...
My Glowworm micron 60FF runs fine from cold but once the system is
warmed up (but not fully up to temperature) it keeps going around the
cycle: turn on, fan starts, gas ignites, runs about 10 seconds, turns
off, waits 10-30 seconds, repeats. This is all with the central
heating thermostat still calling for heat.

So, is this indicative of a failing themistor? In other words is it
indicating that the boiler water temperature is hot enough and hence
not allowing the boiler to run? The boiler stat is turned full on.

Also, when it is running it does a good impression of a steam engine
.... chuff .... chuff .... chuff.


What colour are the LEDs when on (reset & burner) - orange? If so,
replace
PCB. I must have changed 100s of these! The new ones have green LEDs.
Look on the underside of the PCB, there'll be a scorch mark on it.

Someone calls up with a Micron misbehaving, I turn up with my toolbox and
a
PCB.

Yup - the original ones (6 neons) were crap, the later ones (two green
LEDs), however seem to be not that much better from what I'm seeing coming
in for repair

--
geoff

Really? Thats a shame, I like these little boilers. With similar scorch
marks too? I haven't changed many faulty 'new' PCBs I must confess - is it
anything to do with the capacitors they used to send out with the PCB (they
seem to have stopped this recently)? Or anything to do with the thermistor
Glow-worm recommend you replace too? Do you know how may versions of PCB
there have been for the generic Micron (I believe they were on the 3rd or
even 4th)?

Angus

In message , Fentoozler
writes
"raden" wrote in message
...
In message , Fentoozler
writes
"Honeymonster" wrote in message
egroups.com...
My Glowworm micron 60FF runs fine from cold but once the system is
warmed up (but not fully up to temperature) it keeps going around the
cycle: turn on, fan starts, gas ignites, runs about 10 seconds, turns
off, waits 10-30 seconds, repeats. This is all with the central
heating thermostat still calling for heat.

So, is this indicative of a failing themistor? In other words is it
indicating that the boiler water temperature is hot enough and hence
not allowing the boiler to run? The boiler stat is turned full on.

Also, when it is running it does a good impression of a steam engine
.... chuff .... chuff .... chuff.


What colour are the LEDs when on (reset & burner) - orange? If so,
replace
PCB. I must have changed 100s of these! The new ones have green LEDs.
Look on the underside of the PCB, there'll be a scorch mark on it.

Someone calls up with a Micron misbehaving, I turn up with my toolbox and
a
PCB.

Yup - the original ones (6 neons) were crap, the later ones (two green
LEDs), however seem to be not that much better from what I'm seeing coming
in for repair

--
geoff

Really? Thats a shame, I like these little boilers. With similar scorch
marks too? I haven't changed many faulty 'new' PCBs I must confess - is it
anything to do with the capacitors they used to send out with the PCB (they
seem to have stopped this recently)? Or anything to do with the thermistor
Glow-worm recommend you replace too? Do you know how may versions of PCB
there have been for the generic Micron (I believe they were on the 3rd or
even 4th)?

The new ones suffer from a number of different problems of which about
50% seem to be controller faults - which is bad news for me

Another problem is with the bespoke HT transformer which, again, is bad
news for me

I don't know offhand how many issue numbers they've got up to now


--
geoff

"raden" wrote in message
...
In message , Fentoozler
writes
"Honeymonster" wrote in message
groups.com...
My Glowworm micron 60FF runs fine from cold but once the system is
warmed up (but not fully up to temperature) it keeps going around the
cycle: turn on, fan starts, gas ignites, runs about 10 seconds, turns
off, waits 10-30 seconds, repeats. This is all with the central
heating thermostat still calling for heat.

So, is this indicative of a failing themistor? In other words is it
indicating that the boiler water temperature is hot enough and hence
not allowing the boiler to run? The boiler stat is turned full on.

Also, when it is running it does a good impression of a steam engine
.... chuff .... chuff .... chuff.


What colour are the LEDs when on (reset & burner) - orange? If so,
replace
PCB. I must have changed 100s of these! The new ones have green LEDs.
Look on the underside of the PCB, there'll be a scorch mark on it.

Someone calls up with a Micron misbehaving, I turn up with my toolbox and
a
PCB.

Yup - the original ones (6 neons) were crap, the later ones (two green
LEDs), however seem to be not that much better from what I'm seeing coming
in for repair

--
geoff

==============
Is the failure to reach temperature linked directly to the impending PCB
failure or is it just a coincidence?

Cic.

In message , Cicero
writes

"raden" wrote in message
...
In message , Fentoozler
writes
"Honeymonster" wrote in message
egroups.com...
My Glowworm micron 60FF runs fine from cold but once the system is
warmed up (but not fully up to temperature) it keeps going around the
cycle: turn on, fan starts, gas ignites, runs about 10 seconds, turns
off, waits 10-30 seconds, repeats. This is all with the central
heating thermostat still calling for heat.

So, is this indicative of a failing themistor? In other words is it
indicating that the boiler water temperature is hot enough and hence
not allowing the boiler to run? The boiler stat is turned full on.

Also, when it is running it does a good impression of a steam engine
.... chuff .... chuff .... chuff.


What colour are the LEDs when on (reset & burner) - orange? If so,
replace
PCB. I must have changed 100s of these! The new ones have green LEDs.
Look on the underside of the PCB, there'll be a scorch mark on it.

Someone calls up with a Micron misbehaving, I turn up with my toolbox and
a
PCB.

Yup - the original ones (6 neons) were crap, the later ones (two green
LEDs), however seem to be not that much better from what I'm seeing coming
in for repair

--
geoff

==============
Is the failure to reach temperature linked directly to the impending PCB
failure or is it just a coincidence?

It depends on what has actually failed and what is waiting to fail
IYSWIM


--
geoff

"raden" wrote in message
...
In message , Cicero
writes

"raden" wrote in message
...
In message , Fentoozler
writes
"Honeymonster" wrote in message
legroups.com...
My Glowworm micron 60FF runs fine from cold but once the system is
warmed up (but not fully up to temperature) it keeps going around the
cycle: turn on, fan starts, gas ignites, runs about 10 seconds, turns
off, waits 10-30 seconds, repeats. This is all with the central
heating thermostat still calling for heat.

So, is this indicative of a failing themistor? In other words is it
indicating that the boiler water temperature is hot enough and hence
not allowing the boiler to run? The boiler stat is turned full on.

Also, when it is running it does a good impression of a steam engine
.... chuff .... chuff .... chuff.


What colour are the LEDs when on (reset & burner) - orange? If so,
replace
PCB. I must have changed 100s of these! The new ones have green LEDs.
Look on the underside of the PCB, there'll be a scorch mark on it.

Someone calls up with a Micron misbehaving, I turn up with my toolbox
and
a
PCB.

Yup - the original ones (6 neons) were crap, the later ones (two green
LEDs), however seem to be not that much better from what I'm seeing
coming
in for repair

--
geoff

==============
Is the failure to reach temperature linked directly to the impending PCB
failure or is it just a coincidence?

It depends on what has actually failed and what is waiting to fail IYSWIM


--
geoff

=================
I see what you mean. It would be sensible for OP to change the distressed
PCB and see what effect it has on temperature.

Cic.

In article ,
"Cicero" writes:
================
Buy a couple of these: http://www.plumbworld.co.uk/0000-118?eid=0023-000001

I think they're also stocked by Wickes, B&Q etc.

They're reasonably accurate and if one is placed on flow and another on
return they will show the difference between flow and return temperatures
which is probably more significant than a maximum temperature.

Stick them both on the same pipe to start with, and make sure
they read the same (if you are going to be interested in the
differential temperature). A large dollop of heat sink compound
on the back of the thermometer where it contacts the pipe
considerably helps with responsiveness and accuracy.

--
Andrew Gabriel

It's not up to temperature because the pipes in and out of the boiler
are warm but not hot. I would guess no more than 50 degrees C.

Mine has the 2 green LEDs. They don't indicate any fault (i.e. the
boiler believes itself to be operating correctly).

"Honeymonster" wrote in message
oups.com...
It's not up to temperature because the pipes in and out of the boiler
are warm but not hot. I would guess no more than 50 degrees C.


===============
Your room thermostat could be faulty. Try it on a much higher setting and
see if it makes a difference.

Cic.

"Honeymonster" wrote in message
ups.com...
Mine has the 2 green LEDs. They don't indicate any fault (i.e. the
boiler believes itself to be operating correctly).


Still could be a dodgy PCB, dodgy boiler stat (which is incorporated onto
the PCB, or a faulty thermistor which has the incorrect resistance. It
would be unusual for a room stat to go wrong, but you could link it out and
see if the boiler runs for longer.

Angus

For the record, the problem was fixed by replacing the thermistor.