Smoke Testing

Complete combustion testing of a fuel oil fired system, #1 - #6, also requires a smoke test.

When dealing with fuel oil fired heating equipment, also perform a smoke test to help identify incomplete combustion.  A common misconception is that before an oil-fired appliance will produce CO, it will smoke so badly that it will be immediately evident a problem is occurring. 

While it is generally true that a smoky oil flame will produce CO, years of testing experience with electronic instruments has established that the reverse is not always the case. 

An oil-fired unit not producing a measurable amount of smoke is very capable of CO production.  This is often seen when too much combustion air is introduced into the flame which results in a greater volume of flue gases being produced which acts to dilute the smoke to the point where it may not be picked up by the smoke pump filter paper.

Smoke tests are taken from the same sample location as the combustion tests.  A clean piece of filter paper is inserted into the tip of the smoke tester and 10 strokes of the pump are taken.

The filter paper is removed and the dot compared to the Smoke Spot Chart.

Generally, modern residential flame retention burners should be set up for a zero smoke with O₂ readings within manufacturer’s specifications, while an older conventional style burner may be allowed between a #1 and #2 smoke.

A “yellow” dot is an indication of unburned, raw fuel that is escaping the flame pattern and being exhausted with the flue gases.