Black or white smoke emitted from the boiler chimney indicates inadequate combustion leading to excess fuel consumption. Check boiler parameters and settings.
The colour of the smoke emitted from the boiler chimney is a good first check on combustion.
| | Black smoke | White smoke | Grey smoke |
| What it indicates | Low air to fuel ratio, i.e. oxygen deficient combustion | High air to fuel ratio, i.e. oxygen rich system | Optimum air to fuel ratio for combustion |
| Status of combustion | Incomplete combustion | Complete combustion but the excess air carries away useful heat energy | Complete combustion with minimised losses |
| Leads to | Excess fuel consumption due to high unburnt losses | Excess fuel consumption due to high stack losses | Optimised fuel consumption |
Complete combustion with minimised losses leads to optimised fuel consumption by the boiler. This in turn results in reduced fuel bills.
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