What are the two common types of gas used in residential heating systems?

The two common types of gas used in residential heating systems are natural gas and propane. Natural gas is primarily composed of methane and is supplied through a network of pipes and utility services, making it widely available for residential heating. It is often used because it is generally more economical and efficient.

Propane, on the other hand, is stored as a liquid in tanks and is frequently used in areas where natural gas services are not accessible. It is suitable for heating and has a higher energy content per unit volume compared to natural gas, which can also make it advantageous for certain applications.

Both natural gas and propane are widely accepted and used in residential settings, and their combustion characteristics make them suitable for various heating appliances, including furnaces, water heaters, and fireplaces. Other types of gases mentioned in the other options, such as butane and ethane, are less common for residential heating systems due to factors like availability, infrastructure, and energy efficiency considerations.