I have a problem with the above boiler in that the main burner will not light.
It seems that it is not flame sensing as the fan is rinning the pilot lights but the spark gap (SG1) on the control board flashes in a sequence that appears as if it is still trying to light the pilot.

The boiler's GC No. is: 4160166.

How does this boiler sense that the pilot has lit? Is it the electrode that senses that the pilot is lit?

Any help appreciated.

Paul G

In message , Paul G
writes

I have a problem with the above boiler in that the main burner will not
light.
It seems that it is not flame sensing as the fan is rinning the pilot
lights but the spark gap (SG1) on the control board flashes in a
sequence that appears as if it is still trying to light the pilot.

The boiler's GC No. is: 4160166.

How does this boiler sense that the pilot has lit? Is it the electrode
that senses that the pilot is lit?

The pcb senses that the pilot light has lit electronically via the HT
lead

If it's not flame sensing
a) pcb is shagged (technical term)
b) HT lead is broken
c) electrode is not in the flame
d) bad earthing
e) dunno about the mercury switch

--
geoff

Thanks Geoff. The electrode and lead have both been changed and the electdode is in the flame (I assume the resistance of the electrode changes when hot then).
Where should I check for a bad earth? and I am not sure I have a mercury switch, where would it be?

Thanks

Paul

On Wed, 28 Sep 2005 21:44:28 GMT, raden wrote:

In message , Paul G
writes

I have a problem with the above boiler in that the main burner will not
light.
It seems that it is not flame sensing as the fan is rinning the pilot
lights but the spark gap (SG1) on the control board flashes in a
sequence that appears as if it is still trying to light the pilot.

The boiler's GC No. is: 4160166.

How does this boiler sense that the pilot has lit? Is it the electrode
that senses that the pilot is lit?

The pcb senses that the pilot light has lit electronically via the HT
lead

I cant recall whether the netaheat electronic uses a mercury vapour
switch to sense pilot light on ,as the earlier models did ??

Have a look at the pilot light block. If there is a metal post in the
way of the pilot flame,rather like a thermocouple lead head then it is
a mercury vapour switch.

joe




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On Thu, 29 Sep 2005 07:57:27 +0100, Paul G wrote:


raden Wrote:
In message , Paul G
writes-

I have a problem with the above boiler in that the main burner will
not
light.
It seems that it is not flame sensing as the fan is rinning the pilot
lights but the spark gap (SG1) on the control board flashes in a
sequence that appears as if it is still trying to light the pilot.

The boiler's GC No. is: 4160166.

How does this boiler sense that the pilot has lit? Is it the electrode
that senses that the pilot is lit?
-
The pcb senses that the pilot light has lit electronically via the HT
lead

If it's not flame sensing
a) pcb is shagged (technical term)
b) HT lead is broken
c) electrode is not in the flame
d) bad earthing
e) dunno about the mercury switch

--
geoff

Thanks Geoff. The electrode and lead have both been changed and the
electdode is in the flame (I assume the resistance of the electrode
changes when hot then).
Where should I check for a bad earth? and I am not sure I have a
mercury switch, where would it be?

Thanks

There may be models of Netaheats which work more like Profiles and don't
have a mercury vapour bulb for the main gas, but have two electrical gas
valves one for pilot and one for main burner.

When the boiler was working correctly how long was the delay between the
pilot lighting and the main gas. If it was over 10 seconds then you have
the mercury type if was a second or two then you have a something that
works more like a Profile with two gas valves.

If it is the latter then you might have a small break in the ignition lead
- not enough to stop the HT and the ignition but enough to prevent the
electronics from sensing the flame (they conduct a bit) and opening Gas
Valve 2.

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html

In message , Paul G
writes

raden Wrote:
In message , Paul G
writes-

I have a problem with the above boiler in that the main burner will
not
light.
It seems that it is not flame sensing as the fan is rinning the pilot
lights but the spark gap (SG1) on the control board flashes in a
sequence that appears as if it is still trying to light the pilot.

The boiler's GC No. is: 4160166.

How does this boiler sense that the pilot has lit? Is it the electrode
that senses that the pilot is lit?
-
The pcb senses that the pilot light has lit electronically via the HT
lead

If it's not flame sensing
a) pcb is shagged (technical term)
b) HT lead is broken
c) electrode is not in the flame
d) bad earthing
e) dunno about the mercury switch

--
geoff

Thanks Geoff. The electrode and lead have both been changed and the
electdode is in the flame (I assume the resistance of the electrode
changes when hot then).
Where should I check for a bad earth? and I am not sure I have a
mercury switch, where would it be?

Earth from a good earth to where it goes to the pcb and where the
electrode housing is


this switch plugs into the gas valve IIRC

--
geoff

Thanks for your help. I got the cover off the only relay on the cct board, and could see that it was not operating when it should.
When I operated it manually, with a plastic probe, the main burner lit.
So I need a new relay. Any idea where I can get one from? Maplins or RS don't seem to have anything like it.

Paul

On Wed, 28 Sep 2005 11:04:39 +0100, Paul G
wrote:


I have a problem with the above boiler in that the main burner will not
light.
It seems that it is not flame sensing as the fan is rinning the pilot
lights but the spark gap (SG1) on the control board flashes in a
sequence that appears as if it is still trying to light the pilot.

The boiler's GC No. is: 4160166.

How does this boiler sense that the pilot has lit? Is it the electrode
that senses that the pilot is lit?

Any help appreciated.

Paul G

For installation & servicing instructions
try www.partsarena.com/baxii
under Potterton / Boiler / Netaheat / 16/22E

Ian

On Thu, 29 Sep 2005 20:15:36 +0100, Paul G
wrote:




Thanks for your help. I got the cover off the only relay on the cct
board, and could see that it was not operating when it should.
When I operated it manually, with a plastic probe, the main burner
lit.
So I need a new relay. Any idea where I can get one from? Maplins or RS
don't seem to have anything like it.

Paul
Are you sure the relay coil is energised and just not working?perhaps
it isnt even energised becuase something else is wrong?



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In message , Paul G
writes

Thanks for your help. I got the cover off the only relay on the cct
board, and could see that it was not operating when it should.
When I operated it manually, with a plastic probe, the main burner
lit.
So I need a new relay. Any idea where I can get one from? Maplins or RS
don't seem to have anything like it.

I'm sure it's available from both

--
geoff

Well I suppose it could be the supply to the relay, but with the relay coil testing o/c with a digital meter, I will see if I can get a new one.

Paul

I have replaced the cct board as I couldn't get a relay, but I am still getting the same problem, pilot lights ok but main burner won't light??

Paul

"Paul G" wrote in message
...

Paul G Wrote:
Well I suppose it could be the supply to the relay, but with the relay
coil testing o/c with a digital meter, I will see if I can get a new
one.

Paul

I have replaced the cct board as I couldn't get a relay, but I am still
getting the same problem, pilot lights ok but main burner won't light??


IIRC; the pilot light flame heats a sensor which energises
the solenoid in the gas manifold valve and permits gas to flow to
the main burners. [The gas manifold is a multi-port device which
sequentially admits gas; - after the boiler is pressurised (by the fan)
to the pilot light; then after the pilot light has operated to the main
burner(s)]. Is the exteernal vent get-at-able? Can you smell gas
being admitted to the burners? Is the main burner gas solenoid
u/s?

--

Brian