Flame sensor
Alfred Aratoun
I remember from school it should be from 1 - 7 m amp AC!!! but as I was
trouble shooting I got fluctuating reading from 8 to 0 m amps. Is this
normal or should I be getting a steady reading. Are all flame sensors
rated as far as M amp or current the same and can be replaced
universally. I appreciate your suggestions in advance.
Alfred Aratoun
I remember from college it should be from 1 - 7 m amp AC!!! but as I was
trouble shooting I got fluctuating reading from 8 to 0 m amps. Is this
amp or current rating the same and can they be replaced with another
kind. I appreciate your suggestions in advance.
John Mills
>
> Can anybody tell me when testing flame sensor what the m amp reading be?
Depends upon the control. Most want to see over 1 microamp but others
shut down below 3 ua. When York first brought out the Diamond 80
furnace,
they used a board made by Johnson Controls. They had to get rid of it,
it wanted such a strong signal that after some use, the flame rod
dimished
output and the board shut down the furnace. The W-R control is more
forgiving.
--
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ICQ: 18370036
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require STEADY 5 MICRO amps. However, I was on a Siami paint booth just
the other week that required a steady 25.
You need to know what signal your particular controll requires.
what ever it may be, it has to be steady at pilot, high fire, and all
points inbetween.
Jay
Alfred Aratoun wrote:
>
> Can anybody tell me when testing flame sensor what the m amp reading be?
>
> I remember from school it should be from 1 - 7 m amp AC!!! but as I was
> trouble shooting I got fluctuating reading from 8 to 0 m amps. Is this
> normal or should I be getting a steady reading. Are all flame sensors
> rated as far as M amp or current the same and can be replaced
> universally. I appreciate your suggestions in advance.
ftwhd
<iceb...@earthlink.net> wrote:
>Can anybody tell me when testing flame sensor what the m amp reading be?
>
>I remember from school it should be from 1 - 7 m amp AC!!! but as I was
>trouble shooting I got fluctuating reading from 8 to 0 m amps. Is this
>normal or should I be getting a steady reading. Are all flame sensors
>rated as far as M amp or current the same and can be replaced
>universally. I appreciate your suggestions in advance.
>
Its DC micro amps not AC.
Mike
UA Local 370
reply to <ft...@usol.com>
ftwhd
<iceb...@earthlink.net> wrote:
>Can anybody tell me when testing flame sensor what the m amp reading be?
>
>I remember from school it should be from 1 - 7 m amp AC!!! but as I was
>trouble shooting I got fluctuating reading from 8 to 0 m amps. Is this
>normal or should I be getting a steady reading. Are all flame sensors
>rated as far as M amp or current the same and can be replaced
>universally. I appreciate your suggestions in advance.
>
The voltage at the sensor is ac, but because of the great difference
in mass between the flame sensor and the furnace chassis, this voltage
is rectified from ac to dc micro amps. Usually less than 10 micro
amps. Consult the manufacture of the ignition module for the minimum
ua required For instance a Johnson G775 a 776 control requires a
minimum of 0.15 micro amps. Unless the porcelain is cracked there is
no reason to replace a flame sensor. Usually they get a coating of a
silica-type material that acts as an insulator. All that is normally
required is to clean the sensor. Do a before cleaning and after
cleaning test and see the difference. Honeywell flame sensors are
made of a Kanthal rod insulated in ceramic rated at a max temp of 2200
degrees F.
A honeywell S89 requires a 2.5 ua, S90 1.0 ua, S86 1.2 ua, S8610U 1.0
ua, somewhere I have the numbers for fenwal, Robetshaw and W/R but I
need to organize better so I can find it. :) But the bottom line is
check the manufacture of the control for the minimum current required
or, post the specific brand you are working with and maybe someone
will be able to tell you or maybe I'll find my list.
Sonofdawra
>rated as far as M amp or current the same and can be replaced
>universally.
The flame rod is not microamp rated. It is the module that requires a certain
minimum microamp input to prove or continure to prove flame. The microamps
needed varies with make and model.
>but as I was
>trouble shooting I got fluctuating reading from 8 to 0 m amps.
What's the quality of the meter you are using? Obviously if it is going to 0
microamps, then there is no module out there that will continue to prove
ignition under these conditions. Is the flame steady? or is it wavering? If
it is wavering, does it begin to waver after the main blower comes on [if so,
check your heat exchanger].
If you have more detail about what is happening and when it starts to go from 8
microamps down to 0 microamps, repost.
Have a nice day, Ron
MechAcc
Alfred Aratoun <iceb...@earthlink.net> wrote:
> Can anybody tell me when testing flame sensor what the m amp reading
be?
>
was
> trouble shooting I got fluctuating reading from 8 to 0 m amps. Is this
> rated as far as M amp or current the same and can be replaced
>
>
or digital. If it fluxes that much you can clean the flame sensor with
fine emery cloth. If you see lots of pits in the rod or if large pieces
of metal have eroded replace the rod. Sometimes the flame signal
strength can be improved by cleaning the burners.
As far as what the strength the signal should be the manufacturer of
each ignition control will have their own minimum value that they want
the system to see. So White Rodgers will be different than Fenwall and
so on. It is best to have the manufacturers specification sheets on the
controls in addition to the furnace specification sheets. Reason being
one situation on Coleman manufactured home furnaces with Robertshaw
ignition controls Coleman literature states to adjust the thermostat
heat anticipator to the amperage draw. One day looking through the
Uniline, ie Robertshaw, catalog for the controls it stated to set the
heat anticipator to load + 0.1 amp. A difference of 0.1 amp can make
the difference of a burner short cycling on a very cold day.
--
Gary Reecher AKA MechAcc
ICQ # 44165241
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