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Cod Roe April 8th 08 03:05 PM

Baxi Eco 80 Fault
 
My Eco 80 is once again giving me trouble (curse the previous owner who
had it fitted), it lights, waits 6 or 7 seconds then goes out again,
waits another 30 seconds or so and tries again, same thing, and so on to
infinity I assume. Following the fault finding guide in the manual I
checked the flame sensing electrodes, they seem fine, but I cleaned the
tarnish off just in case, checked the sensor current with a multimeter
and got 4-5uA and the manual says approximately 1uA should be present so
I assume this is ok. The manual then says change PCB, so at enormous
expense I have done that, no difference. I'm at a bit of loss as to
what to do next, my only thoughts are the modulating gas valve, does it
light on a low pressure, and then once its happy it has a flame close
that valve and open another to switch up to a high pressure? Any other
possibilities? I have checked the resistance of the temperature sensor
and it is approximately the 11k the manual dictates.

geoff April 8th 08 08:18 PM

Baxi Eco 80 Fault
 
In message , Cod Roe
writes
My Eco 80 is once again giving me trouble (curse the previous owner who
had it fitted), it lights, waits 6 or 7 seconds then goes out again,
waits another 30 seconds or so and tries again, same thing, and so on
to infinity I assume. Following the fault finding guide in the manual
I checked the flame sensing electrodes, they seem fine, but I cleaned
the tarnish off just in case, checked the sensor current with a
multimeter and got 4-5uA and the manual says approximately 1uA should
be present so I assume this is ok. The manual then says change PCB, so
at enormous expense I have done that, no difference. I'm at a bit of
loss as to what to do next, my only thoughts are the modulating gas
valve, does it light on a low pressure, and then once its happy it has
a flame close that valve and open another to switch up to a high
pressure? Any other possibilities? I have checked the resistance of
the temperature sensor and it is approximately the 11k the manual dictates.


Assuming that you are getting a spark and GV operating, i.e. that there
is a flame to sense ...


Reasons for flame sensing failure are

1) pcb - unlikely from what you have said above

2) break in the wire from the electrode to the pcb (are you really
getting 5uA ?) the only way I know of reliably testing the lead is to
give it a tug at both ends to see if the wire is attached to the
connector

3) Electrode not in the flame

4) bad earthing

5) Live and neutral transposed (unlikely unless you have recently done
some electrics)




--
geoff

Cod Roe April 9th 08 01:12 AM

Baxi Eco 80 Fault
 
geoff wrote:

Assuming that you are getting a spark and GV operating, i.e. that there
is a flame to sense ...


Yes, there is a flame to sense.

1) pcb - unlikely from what you have said above


I'm not paying for another one to test that further!

2) break in the wire from the electrode to the pcb (are you really
getting 5uA ?) the only way I know of reliably testing the lead is to
give it a tug at both ends to see if the wire is attached to the connector


I have checked the resistance from tip to spade with a multimeter and
all is fine.

3) Electrode not in the flame


The thing is rigidly fixed, though slightly off the flame, and the
boiler just failed in service without anyone having been near it for
months, so I doubt it had moved. Anyway, I measure a current once it
lights.

4) bad earthing


The earthing hasn't changed, but could you elaborate? Water and gas
primary bonded to the boards riser, and the ring main earth is fully
functional.

5) Live and neutral transposed (unlikely unless you have recently done
some electrics)


Had that some months back, when the plumber had kindly put both ends the
wrong way round, how anyone can do blue to brown and brown to blue
without feeling guilty I don't know.

I checked the gas valve with a manometer and it seems to be delivering
full pressure.

About to give up on this one, and maybe get a Worcester Bosch Greenstar
30Si to replace it, anyone got any comments or suggestions for a better
machine?

geoff April 9th 08 01:34 AM

Baxi Eco 80 Fault
 
In message , Cod Roe
writes
geoff wrote:

Assuming that you are getting a spark and GV operating, i.e. that
there is a flame to sense ...


Yes, there is a flame to sense.

1) pcb - unlikely from what you have said above


I'm not paying for another one to test that further!


I can test Eco 80 pcbs

it's what I do


2) break in the wire from the electrode to the pcb (are you really
getting 5uA ?) the only way I know of reliably testing the lead is to
give it a tug at both ends to see if the wire is attached to the connector


I have checked the resistance from tip to spade with a multimeter and
all is fine.


You didn't read what I typed, did you ?


3) Electrode not in the flame


The thing is rigidly fixed, though slightly off the flame, and the
boiler just failed in service without anyone having been near it for
months, so I doubt it had moved. Anyway, I measure a current once it
lights.


Whatever, if the electrode is not in the flame, it won't flame sense


4) bad earthing


The earthing hasn't changed, but could you elaborate? Water and gas
primary bonded to the boards riser, and the ring main earth is fully
functional.


flame sensing is referenced to earth

if there is a problem with the earthing anywhere within the boiler, this
could cause problems with flame sensing (including to the pcb)


5) Live and neutral transposed (unlikely unless you have recently
done some electrics)


Had that some months back, when the plumber had kindly put both ends
the wrong way round, how anyone can do blue to brown and brown to blue
without feeling guilty I don't know.


So you have let a clueless dickhead near your boiler - best check out
the wiring again then, just to make sure


I checked the gas valve with a manometer and it seems to be delivering
full pressure.


and ?

like measuring the temp sensor - a red herring



About to give up on this one, and maybe get a Worcester Bosch Greenstar
30Si to replace it, anyone got any comments or suggestions for a better
machine?


I have listed the possible reasons for a lack of flame sensing, go and
work through them properly. Start at the beginning, don't make
assumptions and don't take anything for granted - it's easy to overlook
something that you think must be OK

If you want the pcb checked out, I can do it

www.cetltd.com

but I think your problem lies elsewhere

--
geoff

RW[_4_] April 9th 08 06:22 AM

Baxi Eco 80 Fault
 
snip If you want the pcb checked out, I can do it

www.cetltd.com

but I think your problem lies elsewhere



Bookmarked (Don't let UKRM know you do this or you'll be inundated with work
from WC....LOL!)



geoff April 9th 08 08:45 PM

Baxi Eco 80 Fault
 
In message , RW
writes
snip If you want the pcb checked out, I can do it

www.cetltd.com

but I think your problem lies elsewhere



Bookmarked (Don't let UKRM know you do this or you'll be inundated with work
from WC....LOL!)

I gave up with WC last winter ...

--
geoff


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