Higher than normal CO on new Grant Install

[MethodPH]

Wondering if anyone can shed some light. Installed a grant 15-21 internal utility boiler on Wednesday. Has a lo nox burner so co2 needs to be 12.5%. Got the co2 at 12.5% but just can’t get the co level down. Sitting at 75ppm which I know is lower than 100, but all the grants I’ve installed before co usually well below 30ppm. Bit of context it has a vertical balanced flue no bends and is well within max flue length. Just can’t get this job out of my mind. Have tried using the test point on flue and the cleaning door

 

[ShaunCorbs]

Was it brand new when you tested it eg hadn’t been run before?

Could be manufacturing oils burning off

 

[MethodPH]

Was it brand new when you tested it eg hadn’t been run before?

Could be manufacturing oils burning off

Yes mate brand new, guess that could be an option. Just seemed strange. I tested the integrity of the flue by getting end of analyser down the flexible air hose and had no co in the incoming air. Smoke number was 0. I know it’s fine to leave as it’s set to MI co2 level and is under 100ppm but just keeps playing on my mind

 

[ShaunCorbs]

Yes mate brand new, guess that could be an option. Just seemed strange. I tested the integrity of the flue by getting end of analyser down the flexible air hose and had no co in the incoming air. Smoke number was 0. I know it’s fine to leave as it’s set to MI co2 level and is under 100ppm but just keeps playing on my mind

If you can might be worth a re check in a week

 

[MethodPH]

I’ll speak to Grant tomorrow and see what they say, could potentially go back. Just have to explain to the customer why I need to return

 

[MethodPH]

I’ll speak to Grant tomorrow and see what they say, could potentially go back. Just have to explain to the customer why I need to return

Also it was quite windy when I commissioned, wondering if the wind could have created a down draught at the terminal on the high level balanced flue

 

[John.g]

Wasn't there two different verions of those low nox burners, in some cases Grant just changed/swapped the very low nox ones for the "normal" ones but I thought they may have discontinued the very low nox ones.
Lowering the CO2 might reduce the CO?, air temperature compensation chart below.

 

[MethodPH]

Wasn't there two different verions of those low nox burners, in some cases Grant just changed/swapped the very low nox ones for the "normal" ones but I thought they may have discontinued the very low nox ones.
Lowering the CO2 might reduce the CO?, air temperature compensation chart below.

View attachment 95165

Thanks for that, spoke with Grant this morning they said to swap the nozzle out for a new one as nozzle possibly not atomizing all the fuel. Heading back there in a bit