vaillant ecotec co ppm

12 Feb 2014
Reaction score
United Kingdom
hi, I am after some advice from a fellow GSR gasman. I serviced a vaillant ecotec earlier. the boiler was fitted in 2008 and has been serviced yearly. the property has been void for around 10-16 weeks and so the gas has been off at the ecv and the boiler has been inactive the whole time.

anyway I put my analyser in the combustion side of the flue and the readings were extremely high, something along the lines of

CO ppm 31000
Ratio 3.5555
CO2 8.0

I know the co2 isn't that far off but why am I getting 31000 parts per million when it should be no more than 250?

I inpected the main burner and all appeared normal, I also cleaned it and then fitted a new vaillant graphite seal. I also inspected the flue and it was all sealed.

still I was getting these ridiculous readings so I put the analyser into the other side of the flue to get an O2 reading which was correct at 20.9 but there were more than 500 ppm on the oxygen side when it should be 0.

can anybody point me in the right direction as to what the problem is as I have never had readings as high as this before. I often have to adjust them but they are always only slightly out.

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You will not get an answer to this on an open forum

If you register your gsr details, and post in the combustion chamber you will get a lot more help.

It's pretty obvious it's the flue.

Join the CC as its discouraged to discuss gas things in the open forum.
Check all flue seals first, if your getting 500 ppm there must be cross contamination somewhere.
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I will join now didn't relise I could, I don't think its the flue to be honest because the flue goes straight out the wall so there isn't much to check and it all looks fine. I was wondering if possibly a gas valve problem? low pressure or a sticking gas valve not opening? im really unsure as have never had such drastic readings before
I will check all flue seals tomorrow again, if this appears fine where would you go next?
ok to me it all looked fine inside the combustion chamber. I was also told that a crack in the combustion chamber wouldn't effect this? (not saying this is right) but this is was a fellow gasman in my company said. I couldn't see anything wrong with the combustion chamber but in your opinion could this be a big possibility then? the same guy kept saying he thought a gas valve problem?

also I rang vaillant and the guy on the phone said as the c02 was at 8.0 and it needs to be about 9.0 he didn't see much of a problem, I tried explaining that the MI also state it needs to be below 250 ppm but he wasn't interested. he said the most important thing is the c02?
Simple test to check flue integrity,but you should know this. :eek:
No I meant Combustion Chamber. It's a forum for gas men.

Your problem is the flue 100%.
CO ppm 31000
Ratio 3.5555
CO2 8.0

I doubt very much the analyser displayed those readings. ;)

Ratio would have have been around 0.387 @ 8% CO2/31000 ppm.

Fook me 3.5 ratio? :eek:

Was the analyser screaming "get me out of here...." :LOL:
Sorry I meant 0.3555 not 3.5555, co ppm were definitely 31000. Using a Kane analyser within seconds it was beeping loudly saying HIGH CO.

I stopped talking to the vaillant guy as I didn't agree with what he was saying
At what training centre did you take your CPA1 gasman?????

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