Vaillant ecotec plus 637 r1 low 02

[Hobo128]

Been out today to this boiler to do an cp12. Put my anylzer in the air intake and got 13 % 02. Checked all flue seals, change heat ex seal checked checked fan ,removed main heat ex and checked for cracks and leaks. Found nothing.. im stumped . Any ideas????

 

[ShaunCorbs]

ppm?

 

[Last Plumber]

Did you purge the analyser before you stuck it in?
Is it calibrated?

 

[Hobo128]

Ok
Been back today. Changed the flue and the gasket on top of the combustion chamber. Put the anylzer in the air intake and im getting 20.9 % o2 which is great. However, i switched it over to check ratio and had about 9ppm .

 

[ShaunCorbs]

Did it stay like that or drop ?

 

[Hobo128]

The o2 stayed at 20.9. Ratio also stayed the same

 

[ShaunCorbs]

I would say flue seal leak then

 

[Last Plumber]

Do you mean CO?
Where does the flue terminate?
Is it next to or near something that gives off CO?

 

[Hobo128]

Flue terminates directly outside, its a straight run less than a meter with no other fuel burning appliances in the property

 

[masons]

check the flue joints to see if they have been filed , you've got co crossing somewhere