What is a common consequence of improper installation of a gas appliance?

Improper installation of a gas appliance often leads to reduced energy efficiency. This occurs because a gas appliance that is not correctly set up may not operate optimally, leading to excess fuel consumption and wasted energy. Factors such as incorrect venting, poor connections, and inadequate air supply can hinder the appliance's ability to function as intended. Consequently, this inefficiency not only increases operating costs for the user but can also cause a greater environmental impact due to higher greenhouse gas emissions.

In contrast to this, the other choices indicate outcomes that are typically associated with correct installation and operation, rather than the effects of improper setup. Enhanced performance and increased appliance lifespan are benefits that stem from proper installation, which ensures that the appliance operates under ideal conditions. Likewise, decreased fuel consumption is also a result of effective operation, often achieved through proper installation practices that facilitate peak efficiency.