Question 441General Subjects - Assistant Engineer

The correct answer is B) The introduction of air via the makeup water. The primary source of air contamination in a properly filled hydronic heating system is the makeup water. As the system operates and loses water over time, new makeup water is added to the system. This makeup water can contain dissolved air, which can then be introduced into the hot water piping. The presence of this air can reduce the efficiency of the heating system and lead to problems such as air pockets and corrosion. The other options, such as air from the convector steam supply, expansion tank vent, or atmospheric drains tank vent, are not the primary sources of air contamination in a properly filled system.