Gas Fitter Practice Test

Which heating system is likely to cause issues due to the "distribution effect"?

1. A direct vent furnace

2. A convectional vent type boiler

3. A forced air furnace with no return air openings in the furnace room

4. A forced air furnace with a return air opening in the furnace room

The correct answer is: A forced air furnace with a return air opening in the furnace room

The correct answer is based on the impact of air circulation within a heating system. A forced air furnace relies on a system of ductwork to distribute heated air throughout a space. If there is a return air opening located in the furnace room only, it can create a scenario where air is not efficiently circulated back to the heating unit. This limited airflow can lead to uneven heating, leading parts of the living area to feel colder while others may be overly warm. The term "distribution effect" refers to the uniformity and efficiency of heat distribution in a space that can be impaired by inadequate return paths for air. When a return air opening is only in the furnace room, it restricts the system's ability to draw in cooler air from other areas of the building, causing the heating system to work harder and potentially leading to higher energy costs as well as discomfort. In contrast, options like a direct vent furnace or a convectional vent type boiler have designs that either don’t rely on air circulation in the same manner or are constructed to minimize these issues through better design strategies. Therefore, a forced air furnace without a balanced return air system is more likely to face distribution problems, making the presence of a return air opening in the furnace room especially critical to maintaining