Acceptable CO level in flue

ck0

Boiler in question - Alpha Evoke 28. 3 years old.
2 years in a row during annual servicing flue level was 160ppm &130ppm accordingly.
Recently we met a problem when during last annual service it was identified that CO level in flue is 800ppm.

NOTE, we have a CO sensor installed just beside the boiler and until recent never had any alarms!

After service engineer adjusted electromagnetic gas valve the value dropped to 75ppm, but that same same day we have had our first alarm from CO sensor after this service! And two more alarms within one week.
Engineer then advised to get gas valve replaced. It was replaced by another installer by warranty. Everything was cleaned and thoroughly inspected again. Flue analysis after valve replacement and inspection reads CO 350ppm/15ppm (high load/low load accordingly). Installer told that is fine and it is safe. But after a bit of research I found that normally it should be not higher than 100ppm.

I am confused. Can somebody advise? Should I shout loud and call for re-inspection?
P.S. moreover we have two small kids in the house.

corkgsxr

Do you have a printout?

Manual does say 450ppm max.

To me seems high although I'm not familiar with that model. We don't see much alphas down here

Lenar3556

350ppm seems high but the manufacturer would be best placed to advise.

Whatever about a raised CO level in the flue gasses, has the cause of the CO alarm activation been identified and resolved?

jimf

Lenar3556 wrote: »

350ppm seems high but the manufacturer would be best placed to advise.

Whatever about a raised CO level in the flue gasses, has the cause of the CO alarm activation been identified and resolved?

agree re co alarm

Wearb

jimf wrote: »

agree re co alarm

I wonde3r has something changed since rgi visit. Those guys do some sort of leakage test before signing off on a boiler.

jimf

i dont do gas oil only

but from speaking with a few of the guys on here than do gas i know 400ppm is quite expected from new gas boilers

jesus anywhere near 100ppm with oil and we are wondering why

corkgsxr

jimf wrote: »

i dont do gas oil only

but from speaking with a few of the guys on here than do gas i know 400ppm is quite expected from new gas boilers

jesus anywhere near 100ppm with oil and we are wondering why

I fit Bosch. Anything above 60 and I'd be wondering if I pushed a seal

ck0

If in the boiler manual it's defined max CO for this boiler as 450ppm, does that mean it's expected that it can do 450ppm and that is normal?
According to the figures in the cert it's 15ppm at min rate and 350ppm at max rate. For sure we never or almost never utilize it at max rate.
If to be honest I thought that there are regulations re acceptable CO emission level from boilers, but it appears it is up to manufacturer? Ohh well that calms me down a little bit.

The source of CO leak to inside wasn't established. But boiler was fully (almost) re-assembled twice, all joints checked. The engineer who refitted gas valve did checks more thoroughly than the guy who did annual service. So far no CO alarms for one day but it is too early to conclude.

Thanks lads for your answers.
I will check printout and post full results here.

John.G

What was the excess air % as this can affect CO levels if its too low or too high.

Here is a 2003 analysis from a friends Vokera boiler.

Vokera Mynute HE (20 KW) Boiler
Combustion Tests. October 2013
Hi Fire/Low Fire
CO2 9%/9%
CO 83/12
Ratio 0.0009/0.0001
O2 5.1%/5.6%
Excess Air 32.6%/36.9%

DGOBS

If in the boiler manual it's defined max CO for this boiler as 450ppm, does that mean it's expected that it can do 450ppm and that is normal?
According to the figures in the cert it's 15ppm at min rate and 350ppm at max rate. For sure we never or almost never utilize it at max rate.
If to be honest I thought that there are regulations re acceptable CO emission level from boilers, but it appears it is up to manufacturer? Ohh well that calms me down a little bit.

The source of CO leak to inside wasn't established. But boiler was fully (almost) re-assembled twice, all joints checked. The engineer who refitted gas valve did checks more thoroughly than the guy who did annual service. So far no CO alarms for one day but it is too early to conclude.

Thanks lads for your answers.
I will check printout and post full results here.

The manufacture defines acceptable levels for their appliance, but this must also be under a defined max ratio of CO to Co2 (a performance measure) the max rate allowed for a gas boiler is 0.008, so to look at CO alone from a regulatory perspective is incorrect.

The manufacturers of modern boilers usually give an acceptable max ratio in the MI also these days, and usually as low as 0.002-0.004 so under half what the regulations state (as they allow for wear and tear, and ageing of appliances etc)

As for what your measuring at the outside flue terminal, what is important if that the terminal is siting correctly to regulations, to allow fo the dissipation of flue gases in free air, and the correct distances to oder building openings (windows, vents etc) so this dissipation occurs before any possibility of products of combustion re-entering a property.

Also a CO alarm should be fitting (a per MIs) in a locality of the boiler (at high level, again refer to MIs) as a secondary protection should there be any seal/flue failure allowing products of combustion to enter the property. And as you referenced an alarm activation above, your RGI should be able to carry out a room CO safety check with there FGA (takes 15-30 mins) an also carry out an appliance 'sweep' for seal integrity, as the appliance should be totally room sealed, so even if combustion is off, it should be safely discharged outside the property.

jimf

DGOBS wrote: »

The manufacture defines acceptable levels for their appliance, but this must also be under a defined max ratio of CO to Co2 (a performance measure) the max rate allowed for a gas boiler is 0.008, so to look at CO alone from a regulatory perspective is incorrect.

The manufacturers of modern boilers usually give an acceptable max ratio in the MI also these days, and usually as low as 0.002-0.004 so under half what the regulations state (as they allow for wear and tear, and ageing of appliances etc)

As for what your measuring at the outside flue terminal, what is important if that the terminal is siting correctly to regulations, to allow fo the dissipation of flue gases in free air, and the correct distances to oder building openings (windows, vents etc) so this dissipation occurs before any possibility of products of combustion re-entering a property.

Also a CO alarm should be fitting (a per MIs) in a locality of the boiler (at high level, again refer to MIs) as a secondary protection should there be any seal/flue failure allowing products of combustion to enter the property. And as you referenced an alarm activation above, your RGI should be able to carry out a room CO safety check with there FGA (takes 15-30 mins) an also carry out an appliance 'sweep' for seal integrity, as the appliance should be totally room sealed, so even if combustion is off, it should be safely discharged outside the property.

exactly as i was going to say only i didnt have time

Lenar3556

jimf wrote: »

exactly as i was going to say only i didnt have time

Says you - add my name to the bottom of that!

jimf

Lenar3556 wrote: »

Says you - add my name to the bottom of that!

i was i was everybody around here knows i dont wind up anybody

DGOBS

Happy Christmas lads, hope you have a quiet one, and a busy new year!

jimf

DGOBS wrote: »

Happy Christmas lads, hope you have a quiet one, and a busy new year!

and the same to you tony and many of them