Mechanical Inspectors and Plan Reviewers are essential to ensuring safety, efficiency, and code compliance in mechanical system installations across the state. Their role is to verify that contractors have installed HVAC, plumbing, fire suppression, and control systems in accordance with applicable codes and best practices, which is why applicants for Mechanical Inspector or Plan Reviewer licenses must have held a valid Michigan mechanical license for at least one year in three of the following four categories:

• Hydronic Heating and Cooling / Process Piping – Includes boilers, hot water heating systems, chilled water loops, and related piping.
• HVAC Equipment – Covers furnaces, rooftop units, unit heaters, ventilation systems, and air handling equipment.
• Refrigeration – Involves installation and maintenance of commercial refrigeration systems, coolers, and freezers.
• Fire Suppression – Includes sprinklers, fire pumps, standpipes, and related mechanical fire control systems.

These licensing categories ensure that applicants already have hands-on knowledge in key mechanical system areas before stepping into an inspector or plan reviewer role. This practical experience is critical for:

• Interpreting mechanical code requirements
• Reviewing and approving plans
• Conducting thorough inspections
• Identifying safety hazards and noncompliance issues

Mechanical contractors function as general contractors for mechanical systems and are responsible for the installation, integration, and proper operation of a variety of systems, including:

• HVAC (Heating, Ventilation, and Air Conditioning): Proper ductwork sizing and layout, equipment placement, airflow balancing, and integration with control systems.
• Plumbing: Correct pipe sizing, routing, support, backflow prevention, and fixture installation.
• Fire Suppression Systems: Accurate placement of sprinklers, use of approved materials, and proper installation of valves and connections.
• Controls and Automation: Integration of thermostats, sensors, dampers, and other control elements to ensure coordinated system operation.

As an inspector, you're not only verifying that installations meet code—you’re also ensuring systems function together as intended for safety, comfort, and efficiency. Understanding the contractor’s role helps you approach inspections with a systems-based mindset, identifying not just isolated issues but potential impacts on the overall mechanical performance.