•The mechanical code includes additional sections related to cutting and notching not found in the plumbing code. These specific requirements will be referenced when performing the rough and in some cases the final inspections of mechanical equipment and piping.

•These sections are referenced when performing new appliance and equipment inspections. Many times the installer does not follow the manufacturer’s installation instructions and in some cases the equipment is incorrectly located and the requested inspection may need to be aborted. Make sure the equipment is properly located before proceeding with the inspection!

•This section of the code states equipment and appliances shall be installed as required by the terms of their approval, in accordance with the conditions of the listing, the manufacturer’s installation instructions and this code. Manufacturer’s installation instructions shall be available on the job site at the time of inspection! You can’t perform a proper inspection without the installation instructions!

•Equipment and appliances having an ignition source and located in hazardous location and public garages, private garages, repair garages, automotive motor fuel-dispensing facilities and parking garages shall be elevated such that the source of ignition is not less than 18 inches above the floor surface on which the equipment or appliance rests.

•Heat producing equipment and appliances shall be installed to maintain the required clearances to combustible construction as specified in the listing and the manufacturer’s instructions. Such clearances shall be reduced only in accordance with Section 308. Clearances to combustibles shall include such considerations as door swing, drawer pull, overhead projections or shelving and window swing, shutters, coverings and drapes. Devices such as doorstops or limits, closers, drapery ties or guards shall not be used to provide the required clearances.

•Equipment and appliances installed at grade level shall be supported on a level concrete slab or other approved material extending not less than 3 inches above adjoining grade or shall be extended not less than 6 inches above adjoining grade. Such support shall be in accordance with the manufacturer’s installation instructions.

•Guards shall be provided where appliances, equipment, fans or other components that require service and roof hatch openings are located within 10 feet of a roof edge or open side of a walking surface and such edge or open side is located more than 30 inches above the floor, roof or grade below.

•Appliances serving different areas of a building other than where they are installed shall be permanently marked in an approved manner that uniquely identifies the appliance and the area it serves.

•Pipe hangers and supports shall have sufficient strength to withstand all anticipated static and specified dynamic loading conditions associated with the intended use. Pipe hangers and supports that are in direct contact with piping shall be of approved materials that are compatible with the piping and that will not promote galvanic action.

•Piping shall be supported at distances not exceeding the spacing specified in Table 305.4, or in accordance with MSS SP-69.

•Shield plates if piping other than cast-iron or steel are located within 1 ½” from the nearest edge of the member. The shield plates should be 16 gage and extend a minimum of 2” above the sole plates and below top plates.

•Appliances shall be accessible for inspection, service, repair and replacement without disabling the function of a fire-resistant-rated assembly or removing permanent construction, other appliances, venting systems or any other piping or ducts not connected to the appliance being inspected, serviced, repaired or replaced. A level working space at least 30 inches deep and 30 inches wide shall be provided in front of the control side to service an appliance.

•A complete plan must be submitted for the entire exhaust installation including the hood, ductwork, mechanical equipment such as upblastfan, in-line fan, make-up air unit or other equipment.

•Hood suppression system based on equipment located under the hood. (Actual equipment observed during inspection must be confirmed with the submitted approved plan.) Many times the equipment has been changed and improperly placed under the hood.

•Is the hood listed and labeled? *Many times hoods are not listed and labeled and in some cases the label on the hood does not pertain to the actual hood, such as a hood that might reference zero clearance when it actually requires 18” to combustibles. Extremely important to check the manufacturer’s instructions.

•Kitchen hood supports. Most manufacturers require threaded rod supports. Mounting brackets for the threaded rod are usually part of the hood construction.

•Many times installers are trying to hang or support the hood with chain. (Chinese restaurants) (This is not an approved method.)

•Clearance to combustibles = 18” from all parts of the Type 1 Hood, top, sides, back and bottom.

•IMPORTANT Wall construction behind hood.

•Combustibles are not permitted to be located within the wall construction of the back wall. Insulation (kraftpaper), piping such as PVC are just a few of the materials not permitted in the back wall.

•* Many times the installer and the inspector forget about the exposed wall above the hood and behind the hood.

•Kitchen exhaust duct construction for type 1 hoods

•Black iron, stainless steel, and factory made grease duct.

•Steel minimum 16 gage

•Stainless steel minimum 18 gage

•Factory-built listed and labeled in accordance with UL 1978.

•Another common problem is the duct installer connecting class one flexible ductwork to the make-up air plenum above a Type 1 hood. This flexible duct is considered a combustible and must not be located within 18” of the Type 1 hood.

•Duct joint types

•Butt joints, welded flanged joints, overlapping, such as telescoping or bell.

•Problems sealing the corners with butt joints.

•Problems with “bird mouths” on flanged joints.

•Flanged joints also are problems at the corners. Many times in the field we find rather large holes at these locations.

•Duct-to-hood joints welded, brazed, bolted with an approved gasket material.

•Problems with corners when brazing or welding.

•Problems with gasket materials. Installers substitute listed materials for materials such as silicone or general purpose caulk. The AHJ must require proper documentation to validate the product being used!

•Grease duct testing

•Prior to the adoption of the 2012 International Mechanical Code testing was performed many different ways. The code was not specific. Many of the local jurisdictions used IMC Section 102.9, Requirements not covered by this code.

•Most of the tests, including OSBI’s were performed using smoke. When this test was properly performed the smallest hole or defect were revealed. The current code requires a light test. We actually performed a light test according to the code on ductwork

•Many times the required testing must be performed in sections for a proper installation.***

•Roof penetrations of the kitchen exhaust duct through the curb are a major concern.

•Steel and stainless steel require 18” clearance to combustibles. The curb and other roofing materials many times contain combustibles. In order to gain code compliance the duct is wrapped with a listed material.

•The grease duct penetration through the curb to the upblastfan must be tested and wrapped before installation.

•The amount of space between the roof deck penetration and the grease duct is minimal and the rated wrap goes on in two layers which must be properly banded. (manufacturer’s installation instructions.) The wrap must extend inside the curb to the bottom side of the termination to achieve code compliance. The limited space in the cavity would not permit the installer to properly wrap (two layers) and band the wrap.

•Even if the wrap could be correctly installed it would be impossible for the fire marshal or building inspector to physically observe the installation. Please be aware that this wrap is very heavy and tough to work with, especially in a confined space.

•To properly install the duct penetration through the roof and curb The drop piece should extend below the roof deck at least 18”, if possible. A test must then be performed on the drop piece to confirm no leakage. Once the test has been successfully performed the drop piece can now be insulated.

•The listed grease wrap can now be properly applied and banded without installation or inspection issues.

•Once the insulation is complete and inspected the assembly can now be lowered into place in the curb and the exhaust duct installation can be continued.

•The grease duct system is required to be pitched back to the hood or a low point known as a grease reservoir.

•Common problems in the field are incorrectly pitched ducts, flat or level ductwork and pocketed sections.

•Required pitch -Slope not less than one fourth unit vertical in 12 units horizontal (2-percent slope) toward the hood or toward a grease reservoir designed and installed in accordance with Section 506.3.7.1.

•Where horizontal ducts exceed 75 feet in length, the slope shall be not less than one unit vertical in 12 units horizontal. (8.3 percent slope) Explain problems with pitch requirements on runs over 75 feet.

•Prior to the code change which took place 10/16 the pertinent year of the adopted IMC was 2003. The 2003 IMC contained no specific requirements for the proposed grease reservoir. The 2012 IMC contains 7 specific requirements.

•Grease duct cleanouts and openings. The 2012 IMC now contains 7 specific requirements.

•Common problems with the installation of grease duct cleanouts:

•Factory cleanout doors which are not listed for grease duct use.

•Many observed installations contain environmental air duct cleanouts which are not listed for grease duct applications. It is important to check the equipment documentation to confirm correct listing. Environmental cleanout construction, material gage, and gasket material are just several of the materials that may not stand up to temperatures and conditions in a grease duct system and could seriously compromise the system.

•Once the entire duct system from the exhaust hood outlet to the outside exhaust fan has been completed, including required cleanouts, the system is ready to be light tested.

•Once the system has been successfully observed and light tested the duct is now ready for the remainder of the fire wrap to be installed. The wrap must be installed according to the manufacturer’s installation instructions! Pleaseremember you cannot perform the installation or the inspection without the instructions!!!! Items such as cleanouts require special attention and detail!

•Testing of the completed system is required to confirm proper operation before final approval.

•The first test required is a performance test. The performance test includes the determination that the code–required airflow and containment of all cooking vapors will occur.

•The permit holder shall verify capture and containment performance of the exhaust system. This field test

shall be conducted with all appliances under the hood at operating temperatures, with all sources of outdoor air providing makeup air for the hood operating and with all sources of recirculated air providing conditioning for the space in which the hood is located operating. Capture and containment shall be verified visually by observing smoke or steam produced by actual or simulated cooking, such as with smoke candles, smoke puffers, etc.