Mechanical Code OverviewHVAC Mechanical Code Overview - Many people unfamiliar with air conditioning and heating do not know that air conditioning and heating system installation is regulated by the mechanical code many municipalities.

HVAC Mechanical Code Overview | Heating and Cooling Codes

These municipalities usually have an inspection department which sends inspectors out to inspect new HVAC air conditioning and heating system installations. A few municipalities apply there own mechanical code while many others use the International Mechanical Code or another code resource which is applicable to air conditioning and heating installations. Some use a combination on inspections and it is wise to find out before installing air conditioning and heating equipment to find out what your local municipality uses for inspections before installing and mechanical air conditioning and heating equipment.

HVAC Mechanical Code Overview - Authorities Having Jurisdiction (AHJ)

Also be aware that different jurisdictions (State and local) require someone licensed to install some equipment which requires advanced skills, knowledge, and experience to install correctly. Permits are required and only a licensed HVAC or Electrical master can apply for the permits in some jurisdictions. If someone were to go ahead and decide to install some mechanical air conditioning and heating equipment on their own without obtaining permits to complete the job this person can be fined and the residence or building condemned if the equipment is found to be a hazard to the safety of occupants.

Many jurisdictions base their laws on code books like the International Mechanical Code, Various Residential and Commercial Code Books, and the National Electrical Code. These books are written and evaluated by recognized professionals with many years experience in their related disciplines. There are also liability issues involved in not obtaining permits and inspections for some mechanical HVAC installations. It is always best to do the job safely and by the book so get the proper permits and have the job inspected.

The following is a general overview of the mechanical code and what it covers for safe and proper installation of HVAC air conditioning and heating equipment.

HVAC Mechanical Code Overview - International Mechanical Codes References

The Mechanical Code makes references to ANSI (American National Standards Institute), API (American Petroleum Institute), ARI (Air-Conditioning and Refrigeration Institute), ASHRAE (American Society of Heating, Refrigeration, and Air Conditioning Engineers), ASME (American Society of Mechanical Engineers), ASTM (American Society for Testing and Materials), AWS (American Welding Society), Codes from various recognized code references and agencies, CSA (Canadian Standards Association), FS or Federal Specifications Standards, IIAR (International Institution of Ammonia Refrigeration), MSS (Manufacturers Standardization Society of the Valve and Fittings Industry), NAIMA (North American Insulation Manufacturers Association), NFPA (National Fire Protection Association), SMACNA (Sheet metal and Air Conditioning Contractors National Association), STI (Steel Tank Institute), and UL or Underwriters Laboratories.

HVAC Mechanical Code Overview

Mechanical Code Administration

The prelude chapter of the Mechanical Code covers applicability of the code and administration. It covers the general powers of the mechanical inspectors and their duties to protect the safety of the public. Other parts of this prelude cover permits, inspections, violations, and offers a means of appeal. Definitions and terminology are also covered.

Basic Installation of Mechanical Equipment

The second part of the Mechanical Code covers general regulations which pertain to location of installation of mechanical air conditioning and heating equipment, a piping support table, access and future servicing considerations, condensation piping drains and materials, drain types, minimum clearances around mechanical equipment, and secondary drains for condensation.

Ventilation Code Overview - Ventilation

The next part of the Mechanical Code deals with ventilation from natural ventilation for mechanical ventilation. There a tables and charts offering clearances and louver and grill information for minimum amount of required ventilation. This only includes ventilation for fresh air and does not cover minimum requirements for combustion air which is covered later in another part of the mechanical code.

Exhaust Systems

The next part of the Mechanical Code covers exhaust systems including dryer vents, kitchen exhaust systems, paint rooms, movie projection room exhaust, dry-cleaning appliances, LP gas facilities, public garages, and structures housing hazardous materials. Commercial kitchen exhaust are covered along with commercial kitchen make-up air requirements. Tables include minimum duct sizes and thickness of sheet metal for exhaust ducts. Single wall metal chimneys are also covered at the end of this section.
Common Sense Safety and the Codes

Duct Systems

This section of the Mechanical Code covers duct systems including plenums and wiring requirements in plenums and ducts when wire is ran through these areas. Duct construction and installation and insulation duct work is covered in this chapter. Air filters and filtration systems, smoke detectors installed in ducts, and fire and smoke dampers installed in duct systems are covered.

Combustion Air

This section of the Mechanical Code is for installation of appliances which consume air for combustion this chapter offers minimum code requirement for the necessary amount of air for the process of combustion. It covers forced combustion air and combustion air ducts along with duct opening obstructions and location and protection.

Chimneys and Vents

This part of the Mechanical Code offers information about requirements for chimneys and ventilation for specific appliance types and vent type. Do and don’ts for using chimneys for ventilation of combustion by products and termination of vents and chimneys above the roof. Tables include minimum size of vents for BTU/h of appliances and minimum distances of vents to combustible materials.

Special Appliances, Fireplaces, and Solid Fuel Burning Appliances

This section of the Mechanical Code covers fireplaces, fireplace stoves and heaters, special appliances which produce heat or are used for cooking, gas logs, incinerators and crematories, wall furnaces, floor furnaces, direct fired air heating equipment, infrared radiant heaters, clothes dryers, illuminating appliances, sauna heaters, engine and gas turbine-powered equipment and appliances, pool and spa heaters, cooking appliances, forced warm air furnaces, unit heaters, unvented room heaters including unvented gas logs, vented room heaters, kerosene and oil fired stoves, small ceramic kilns, and finally cooling towers, evaporative condensers, and fluid coolers.

Boiler Code Overview - Boilers, Water Heaters, and Pressure Vessels

This section of the Mechanical Code covers installation, alteration, and repair of boilers, water heaters, and pressure vessels. It covers boiler connections, safety and pressure relief valves and controls, boiler low water cutoffs, steam blow off valves, hot water boiler expansion tanks, gauges on hot water and steam boilers, and testing of boilers and pressure vessels. It is important to note that this section is also applicable to LP Containers, bulk oxygen storage tanks, and medical gases.

Refrigeration Code Overview - Refrigeration

This section of the Mechanical Code covers refrigeration including the purity of refrigerants, recovered refrigerants, reclaimed refrigerants and refrigeration classification. Includes information on storage, ventilation requirements for storage areas and refrigeration equipment rooms, refrigeration alarms and detectors for safety of occupants, refrigerant piping, and field testing of refrigerant piping systems.

Hydronic Piping

This section of the Mechanical Code covers pipe materials, joints and connections, piping insulation, valves, transfer fluid, testing of hydronic pipe, and embedded piping.

Fuel Gas Piping

This section of the Mechanical Code covers gas pipe, materials, installation, and sizing for LP and natural gas. This section has equations for sizing pipe and BTU requirements for equipment including length of run of pipe, pressure of gas, and specific gravity. Tables are also included for pipe sizing, length of run, and specific gravity and pressure. Included in this section is requirements and code for gas shut off valves, two-psi and higher gas piping, gas flow controls including regulators, appliance connections, CNG gas-dispensing systems, and supplemental and standby gas supplies.

Fuel Oil Piping and Storage – HVAC Mechanical Code Overview

This section of the Mechanical Code covers materials used for fuel oil storage tanks and fuel oil piping, fuel oil pipe joints and connections, fuel pipe support, fuel oil system installation, oil gauges, fuel oil shutoff valves, and testing of fuel oil piping.

Solar Systems – HVAC Mechanical Code Overview

This section of the Mechanical Code covers the installation and materials used for solar systems. Also covers heat transfer fluids, collectors, and thermal storage units.

HVAC Mechanical Code Overview

High Performance HVAC

HVAC Mechanical Code Overview

To learn more about heating systems and HVAC use this resource.

See the About the Author page for information about the author of this article.

Share your HVAC Photos or ask a question about your HVAC System by uploading a photo of it.

Photo Uploads
Enter your name so we can credit you
If you have a website enter your website URL for additional credit
If you want to include a description then do so here.
Drop a file here or click to upload Choose File
Maximum upload size: 100MB
jpe, jpeg, jpg, gif, png, bmp, docx, doc, txt and PDF files allowed to be uploaded. Limit 15 files total and 100 mb/s max size.