Gas Fitter Practice Test

What is the effect of a cracked heat exchanger in a furnace?

1. Increases air circulation

2. Decreases efficiency of heat exchange

3. Causes a strong combustion gas odour

4. Improves furnace safety

The correct answer is: Causes a strong combustion gas odour

A cracked heat exchanger in a furnace primarily leads to the release of combustion gases that are supposed to be contained within the heat exchanger. This can generate a strong combustion gas odor, which is a critical warning sign of a potential safety hazard. When the heat exchanger is compromised, it can allow harmful gases, such as carbon monoxide, to escape into the living space, posing serious health risks to occupants. Understanding the role of the heat exchanger in a furnace is crucial. Its primary function is to transfer heat from the combustion process to the air that circulates through the home while keeping these gases sealed away from the indoor environment. A crack disrupts this function, leading to the possibility of both odor and danger due to gas leakage. The other choices do not align with the implications of a cracked heat exchanger. Increased air circulation is not directly related to the condition of the heat exchanger itself; rather, it refers to the system’s ability to distribute air, which may remain unchanged. Decreased efficiency of heat exchange might occur, but it’s secondary to the more immediate and severe issue of gas leakage. Additionally, a crack in the heat exchanger certainly does not improve furnace safety; instead, it significantly compromises it.