Grant 90 V3 Boiler puffing & fumes

Hello Everybody,

I own a six years old Grant 90 V3 boiler. It is a good boiler in terms of the output. However, from last few days I am noticing that there is the black fumes/smoke coming directly from an outside flue as I turn on the boiler. Any suggestions on what exactly the problem could be.

Looking for help on urgent basis


Hi Gary, I would like to share the some possible reasons behind your problem along with the solutions. These are as follows:

  1. If the flue is congested then, clean the flue
  2. For inadequate flue draught you have to check the flue draught thoroughly while improving it as required
  3. If there is an adequate supply of the combustion air to the burner then, check that the extract fan of the boiler is not drawing the burning gases from the burner
  4. Lastly, if a flue liner or pipe is very large or current load is unlined then, check the size or condition of the flue & change if required

You can contact a skilled Grant boiler engineer for detailed analysis