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Flue CO2 question?



 
 
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  #1  
Old January 4th 05, 06:40 PM
Harry Bloomfield
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Default Flue CO2 question?

Hi,

I'm not personally involved with this problem so supplying more
information will be difficult...

A permanently installed flue gas instrument (LED display) measuring CO2
levels indicates 20% with no combustion gases passing up the flue. With
the burner system in operation this level declines to an indicated 9%.

My immediate response is that the meter is obviously working the wrong
way, if CO2 levels go down with combustion. The instrument is suggested
to be clearly marked that it reads 'CO2'.

What is the normal level of C02 in the atmosphere as a percentage and
will the instrument be designed to detect the additional amount of CO2
(above the atmospheric normal), or to measure the overall level?

--


--

Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.org

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  #2  
Old January 4th 05, 07:20 PM
Ian Stirling
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Default

Harry Bloomfield wrote:
Hi,

I'm not personally involved with this problem so supplying more
information will be difficult...

A permanently installed flue gas instrument (LED display) measuring CO2
levels indicates 20% with no combustion gases passing up the flue. With
the burner system in operation this level declines to an indicated 9%.

My immediate response is that the meter is obviously working the wrong
way, if CO2 levels go down with combustion. The instrument is suggested
to be clearly marked that it reads 'CO2'.

What is the normal level of C02 in the atmosphere as a percentage and
will the instrument be designed to detect the additional amount of CO2
(above the atmospheric normal), or to measure the overall level?


If it's oxygen, that might be broadly plausible.
Oxygen levels are 20% in normal atmosphere, and 9% would not be utterly
unreasonable (though maybe a bit high) for exhaust.

For CO2, well, there is a fault.
IIRC normal range is 10-20ppm.
  #3  
Old January 4th 05, 07:21 PM
Mike Harrison
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Default

On Tue, 04 Jan 2005 18:40:30 GMT, Harry Bloomfield wrote:

Hi,

I'm not personally involved with this problem so supplying more
information will be difficult...

A permanently installed flue gas instrument (LED display) measuring CO2
levels indicates 20% with no combustion gases passing up the flue. With
the burner system in operation this level declines to an indicated 9%.

My immediate response is that the meter is obviously working the wrong
way, if CO2 levels go down with combustion. The instrument is suggested
to be clearly marked that it reads 'CO2'.

What is the normal level of C02 in the atmosphere as a percentage and
will the instrument be designed to detect the additional amount of CO2
(above the atmospheric normal), or to measure the overall level?

--


Sounds like a dodgy meter -
http://royal.okanagan.bc.ca/mpidwirn...ndclimate.html

Says Co2 is normally 0.036% of atmosphere.

  #4  
Old January 4th 05, 07:37 PM
Morten
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Default


"Harry Bloomfield" wrote in message
...

A permanently installed flue gas instrument (LED display) measuring CO2
levels indicates 20% with no combustion gases passing up the flue. With
the burner system in operation this level declines to an indicated 9%.


Are you sure it's not measuring O2 ie. Oxygen, that would explain the
figures and they sort of make sense. 20% is normal levels of Oxygen and 9
sound about right when the boiler is running, depending on how the boiler
has been setup.


My immediate response is that the meter is obviously working the wrong
way, if CO2 levels go down with combustion. The instrument is suggested
to be clearly marked that it reads 'CO2'.


If' that is the case then the meter needs calibration, or is connected to a
high flue that stratisfies because CO2 is heavier than the rest of the air.

Does it decrease below 9% when the boiler runs the fan before ignition?


What is the normal level of C02 in the atmosphere as a percentage and
will the instrument be designed to detect the additional amount of CO2
(above the atmospheric normal), or to measure the overall level?


2-3% if I remember correctly...


/Morten




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  #5  
Old January 4th 05, 08:38 PM
Roger
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Default

The message
from Harry Bloomfield contains these words:

A permanently installed flue gas instrument (LED display) measuring CO2
levels indicates 20% with no combustion gases passing up the flue. With
the burner system in operation this level declines to an indicated 9%.


My immediate response is that the meter is obviously working the wrong
way, if CO2 levels go down with combustion. The instrument is suggested
to be clearly marked that it reads 'CO2'.


What is the normal level of C02 in the atmosphere as a percentage and
will the instrument be designed to detect the additional amount of CO2
(above the atmospheric normal), or to measure the overall level?


I am not sure of the exact amount but it sure as hell isn't 20%.

Consults dictionary .03% CO2.

However Oxygen is at 20.95% so is the meter measuring oxygen as it makes
sense for that to be considerably lower in combustion gases.

--

Roger
  #6  
Old January 5th 05, 02:13 AM
Andrew Gabriel
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Default

In article ,
Harry Bloomfield writes:
Hi,

I'm not personally involved with this problem so supplying more
information will be difficult...

A permanently installed flue gas instrument (LED display) measuring CO2
levels indicates 20% with no combustion gases passing up the flue. With
the burner system in operation this level declines to an indicated 9%.


As others have said, this sounds like the oxygen reading.
Combustion analysers often don't measure CO2 directly because it's
hard to do continuously in that type of unit. Instead they measure
O2 and C0 levels, and then calculate the CO2 from that based on the
O2 input assumed to be 21% and type of fuel in use.

--
Andrew Gabriel
  #7  
Old January 5th 05, 07:13 PM
Harry Bloomfield
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Posts: n/a
Default

Andrew Gabriel wrote :

As others have said, this sounds like the oxygen reading.
Combustion analysers often don't measure CO2 directly because it's
hard to do continuously in that type of unit. Instead they measure
O2 and C0 levels, and then calculate the CO2 from that based on the
O2 input assumed to be 21% and type of fuel in use.


Thanks all...

As several have suggested, I think it must be an oxygen measuring
instrument rather than CO2. It was just a description via the phone and
the op insisted it was clearly marked as measuring CO2. Clearly he was
mistaken.

--


--

Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.org

 




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