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moogwai

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Gas Engineer
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Hi Guys, just a quick one.... i was comissioning a new boiler the other day (ideal logic combi 30) i put my fga on it and ran at full rate and was getting a ratio of 0.009!! co2 reading was 9.32% and gas rate/working pressures were fine. Looked at mi's and they stated that 0.004 was the target. Now this being a brand new boier should i need to be fiddleing around with it?
I went on a wb cdi course earlier in the year and the fella said that when doing a fga check he would always go by the co2 reading as this is the gas emissions and as long as this is below 11% there would be no need to take any further action. What's your take on this?
 
B.S,7967 part 3 says that if you get a reading above 0.008 on a new combi boiler to contact the manufacturer
 
Some manufacturers tell you not to test new boiler installs. I had something like.0008 on a Worcester Bosch 30Si I installed recently. Called manufacturer as I was concerned. Burner pressure and gas rate were spot on.

Anyway, they tell me that I shouldn't test on original install as it's like a new car and will take a while to 'bed in'. However on its first service it must be within the limits they state.

I was suprised, but as we all know, manufacturers instructions are final say. So give manuacturer a call, might be same thing.
 
Hi Guys, just a quick one.... i was comissioning a new boiler the other day (ideal logic combi 30) i put my fga on it and ran at full rate and was getting a ratio of 0.009!! co2 reading was 9.32% and gas rate/working pressures were fine. Looked at mi's and they stated that 0.004 was the target. Now this being a brand new boier should i need to be fiddleing around with it?
I went on a wb cdi course earlier in the year and the fella said that when doing a fga check he would always go by the co2 reading as this is the gas emissions and as long as this is below 11% there would be no need to take any further action. What's your take on this?
You sure you haven't missed out a zero there and your ratio was 0.0009?
 
i thought i read on gas safe tb recently that a condensing boiler must be under 0.004 not 0.008 anymore and classified as AR
 
Follow the MI, when your ratio was 0.009 what was your co reading as a matter of interest?
Ring Ideal to confirm levels
01482 445570
 
just checked the TB's, as said check with Manufacturer. Also all manufactuers should have updated their MIs as over 0.004 is AR n over 0.008 is ID. as long as they are condensing with air/gas ratio valves.

Unless in writing from Manufacturer
 
just checked the TB's, as said check with Manufacturer. Also all manufactuers should have updated their MIs as over 0.004 is AR n over 0.008 is ID. as long as they are condensing with air/gas ratio valves.

Unless in writing from Manufacturer

I just found it too, TB126. I don't know the Ideal Logic, does it have an air/gas ratio valve? I'd definititely say this was one for the manufacturers advice
 
i don't know this boiler either. generally i dont like ideal. but would have thought it to have a ratio valve
 
I'm gonna ring ideal tomorrow and see what they say. Thanks for your input lads,will report back.
 
This ratio reading 0.009 with 9.32%CO2 indicates that the CO reading was 850ppm. Way, way to high.
 
Probably missed a zero, easily done. Still too high, but as I have said, manufacturer may say its ok until first service as it's a new install. Then again maybe they won't!
 
ok...just been back to check it once more,turns out i did miss a zero so it now reads 0.0009 phoned ideal and they said its fine as the action level is 0.004....i think we get confused about the number of zero's we need to be reading when doing a fga! i now feel like a right forrest gump!
 
Really pleased to hear that. CO 85ppm CO2 9.3%, CO:CO2 0.009. Satisfactory.
 
ok...just been back to check it once more,turns out i did miss a zero so it now reads 0.0009 phoned ideal and they said its fine as the action level is 0.004....i think we get confused about the number of zero's we need to be reading when doing a fga! i now feel like a right forrest gump!

easily done mate, no-one's perfect.
I think my analyser taps out at 200ppm CO so i couldn't reach those figures without it throwing a wobbly, i don't know if they're all the same though
 
Most low range analysers saturatate at 2,000 to 4,000 ppm CO. If you have a band A boiler with zero governor an acceptable reading would normaly be 0.0002. At 10% CO2 and 200ppm CO your ratio would be 0.0002.
 
Most low range analysers saturatate at 2,000 to 4,000 ppm CO. If you have a band A boiler with zero governor an acceptable reading would normaly be 0.0002. At 10% CO2 and 200ppm CO your ratio would be 0.0002.

to be honest i didn't notice the CO2 at the time, was probably way up, i just saw the CO hit 200 then computer said no!

surely you meant 0.002 Reg Man? tricky them pesky noughts looks like we're all at it now :eek:)
 
Ratio calculations

ppm in CO divided by CO2 in percent multiplied by 10000


eg

85ppm
9.3% X 10000 = 0.0009

For CO2 calculation from oxygen

CO2 maximum for nat gas is 11.9%

CO2 =

CO2max (20.9 - O2 reading)
20.9

eg

CO2 =

11.9 x (20.9 -4) =
20.9

201.11 = 9.62% CO2
20.9
 
to be honest i didn't notice the CO2 at the time, was probably way up, i just saw the CO hit 200 then computer said no!

surely you meant 0.002 Reg Man? tricky them pesky noughts looks like we're all at it now :eek:)
Yer your quite right all these 0000000's easy done.
 
yep all the 0.0000 can easily get mixed up

trigger value on my sheet for combi,s is 0.008 altho mi,s might say diffrent so 0.0009 would be well in
 
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those bloody noughts. I still keep looking at my sheet just to be on the safe side as i always keep questioning myself whether it's 1, 2, or 3 bloody zero's.
 
yep all the 0.0000 can easily get mixed up

trigger value on my sheet for combi,s is 0.008 altho mi,s might say diffrent so 0.0009 would be well in
Yer you are right for many boilers, but Mi's over rule guidance in CPA1. Most band A boilers (zero governed) require 0.002 ratio.
 
just as an easy trigger to remember the cut off point on the analyser ratio tests

JAMES BOND 007

When i see the ratio near this i consult the MIs

works for me but im a bit of a saddo
 
i was told 0.004 or below ok 0.004 to 0.008 needs servicing, above 0.008 I,D switch off and find out why
 
ok...just been back to check it once more,turns out i did miss a zero so it now reads 0.0009 phoned ideal and they said its fine as the action level is 0.004....i think we get confused about the number of zero's we need to be reading when doing a fga! i now feel like a right forrest gump!


i think you are being very unfair to Forrest Gump:p
 
i was told 0.004 or below ok 0.004 to 0.008 needs servicing, above 0.008 I,D switch off and find out why


Thats how BG work. Most newer boiler state a ratio in the MI's. Worcester are 0.0020 for example. Also if its above 0.0080 on a boiler then its only AR not ID.
 
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