Final answer:
Local municipal authorities or building department are responsible for issuing permits for gas fireplace installations, ensuring compliance with local regulations.
Step-by-step explanation:
The entity responsible for issuing permits for a gas fireplace installation is typically the local municipal authorities or building department. They are the ones who ensure that the installation complies with local building codes and safety regulations. Although homeowners and general contractors are usually involved in the process, such as applying for the permit or carrying out the installation, they do not issue the permits themselves. Similarly, the gas company may be involved in providing the service and ensuring the gas supply is up to code, but they do not issue building permits.