# Commercial Generator Exhaust and IMC 501



## jar546 (Aug 20, 2020)

Do you consider a commercial generator exhaust system a mechanical system as covered by the IMC?


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## steveray (Aug 20, 2020)

EXHAUST SYSTEM. An assembly of connected ducts, plenums,
fittings, registers, grilles and hoods through which air
is conducted from the space or spaces and exhausted to the
outdoor atmosphere.

Like the muffler and tailpipe? No....if you are carrying the exhaust to outside the building somehow, maybe, but the details would matter....Interior generator?

MECHANICAL SYSTEM. A system specifically addressed
and regulated in this code and composed of components,
devices, appliances and equipment.


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## steveray (Aug 20, 2020)

[A] 101.2 Scope. This code shall regulate the design, installation,
maintenance, alteration and inspection of mechanical
systems that are permanently installed and utilized to provide
control of environmental conditions and related processes
within buildings. This code shall also regulate those mechanical
systems, system components, equipment and appliances
specifically addressed herein. The installation of fuel gas distribution
piping and equipment, fuel gas-fired appliances and
fuel gas-fired appliance venting systems shall be regulated by
the International Fuel Gas Code.


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## cda (Aug 20, 2020)

jar546 said:


> Do you consider a commercial generator exhaust system a mechanical system as covered by the IMC?



Why the question


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## jar546 (Aug 20, 2020)

cda said:


> Why the question




Generator inside a building exhausts to the exterior.  Neighbor complaining about fume


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## steveray (Aug 20, 2020)

Would you regulate the exhaust if the genny was outside?


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## jar546 (Aug 20, 2020)

steveray said:


> Would you regulate the exhaust if the genny was outside?


I don't see where the IMC covers a generator outside of a building.


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## cda (Aug 20, 2020)

IFGC??   IFC 

So how far is the end of the exhaust pipe to complainer and property line??

Does it go straight out or out and turn up?

It only runs once a month and has been there for years.


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## steveray (Aug 20, 2020)

I don't see where it regulates it inside the building....

[A] 101.2 Scope. This code shall regulate the design, installation,
maintenance, alteration and inspection of mechanical
systems that are permanently installed and utilized to provide
control of environmental conditions and related processes
within buildings.


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## jar546 (Aug 20, 2020)

cda said:


> IFGC??   IFC
> 
> So how far is the end of the exhaust pipe to complainer and property line??
> 
> ...



It comes straight out about 8' above grade and points right at the house which is more than 10' away


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## steveray (Aug 20, 2020)

Is there a particular section of the IMC you would like to use?


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## mtlogcabin (Aug 20, 2020)

This is all I could find but I do not see where it will answer your neighbor complaint problem unless it is in NFPA 37 or the manufactures installation instructions.

2018 IBC and IFC
[F] 2702.2.5 Exhaust systems.
Standby power shall be provided for common exhaust systems for domestic kitchens located in multistory structures as required in Section 505.5 of the International Mechanical Code. Standby power shall be provided for common exhaust systems for clothes dryers located in multistory structures as required in Section 504.10 of the International Mechanical Code and Section 614.10 of the International Fuel Gas Code.

IMC SECTION 915
ENGINE AND GAS TURBINE-POWERED
EQUIPMENT AND APPLIANCES

915.1 General.
The installation of liquid-fueled stationary internal combustion engines and gas turbines, including exhaust, fuel storage and piping, shall meet the requirements of NFPA 37. Stationary engine generator assemblies shall meet the requirements of UL 2200.

915.2 Powered equipment and appliances.
Permanently installed equipment and appliances powered by internal combustion engines and turbines shall be installed in accordance with the manufacturer’s instructions and NFPA 37.


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## cda (Aug 20, 2020)

I thought generator exhaust had to be five feet from building??


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## cda (Aug 20, 2020)

Some threads for thought::::







						Emergency Generator Location
					

This is the best forum I could think of to ask this question. Not really electrical but.......  A retirement center is looking to install an emergency generator. The building is approximately fifteen feet tall. The exhaust from the generator will be around fifteen feet away from the building...



					www.thebuildingcodeforum.com


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## north star (Aug 20, 2020)

*# ~ # ~ #*

We had a situation similar to this a few years back with
a Genny at one of our facilities...….The Genny exhaust fumes
would exit thru the Genny exhaust piping, and then the
prevailing winds would direct the exhausts back in to the bldg.
that the Genny was servicing.

We spent $$$ to add some custom piping to the existing exhaust
piping and take it up to just above the roof line [ almost 25 ft.
in height ] ...…..No Codes involved, just practicality \ common sense.

No problems since then !

*# ~ # ~ #*


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## north star (Aug 20, 2020)

*$ = $*

From the `15 IPMC, Section 302.6 - Exhaust vents:  "Pipes, ducts,
conductors, fans or blowers shall not discharge gases, steam,
vapor, hot air, grease, smoke, odors or other gaseous or
particulate wastes directly upon abutting or adjacent public or
private property or that of another tenant".

*$ = $*


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## Rick18071 (Aug 21, 2020)

*2015 International mechanical Code

501.3.1 Location of exhaust outlets. *For other product-conveying outlets: 10 feet (3048mm) from the property lines; 3 feet (914 mm) from exterior walls and roofs; 10 feet (3048 mm) from operable openings into buildings; 10 feet (3048 mm) above adjoining grade.



*NFPA 37 Standard for the Installation and Use of Stationary Combustion Engines and Gas Turbines*
4.1.4 Engines Located Outdoors. Engines and their weatherproof housing, if provided, that are installed outdoors shall be located at least 5’ from openings in walls and at least 5’ from structures having combustible walls. A minimum separation shall not be required where either of the following conditions exist:

1. All walls of the structure that are closer than 5’ from the engine have a fire resistance rating of at least 1 hour.

2. The weatherproof enclose is constructed of noncombustible materials and it has been demonstrated that a fire within the enclosure will not ignite combustible materials outside of the enclosure


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## steveray (Aug 21, 2020)

Not sure that fits fully, but i'd go with it maybe...

501.1 Scope. This chapter shall govern the design, construction
and installation of mechanical exhaust systems, including
exhaust systems serving clothes dryers and cooking
appliances; hazardous exhaust systems; dust, stock and refuse
conveyor systems; subslab soil exhaust systems; smoke control
systems; energy recovery ventilation systems and other
systems specified in Section 502.

EXHAUST SYSTEM. An assembly of connected ducts, plenums,
fittings, registers, grilles and hoods through which air
is conducted from the space or spaces and exhausted to the
outdoor atmosphere.


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## klarenbeek (Aug 24, 2020)

It doesn't fit the code definition for exhaust system because its not exhausting air, its actually exhausting products of combustion. That makes it a vent system, not an exhaust system same as a power vented furnace or boiler.  Termination locations would be covered in Chapter 8 of the IMC if its a gasoline or fuel oil generator or in Chapter 5 of the IFGC if it is propane or natural gas, but basically the same for either one.  Manufacturer's installation instructions must also be followed.

Generators are regulated by the IMC/IFGC because they are listed under Specific appliances as mtlogcabin said. The IFGC version of that section is 615 and is basically the same as IMC 915.  Whether it sits inside or outside doesn't matter, or air conditioners and rooftop HVAC units wouldn't be covered by code either based on that logic.


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## jar546 (Aug 24, 2020)

klarenbeek said:


> It doesn't fit the code definition for exhaust system because its not exhausting air, its actually exhausting products of combustion. That makes it a vent system, not an exhaust system same as a power vented furnace or boiler.  Termination locations would be covered in Chapter 8 of the IMC if its a gasoline or fuel oil generator or in Chapter 5 of the IFGC if it is propane or natural gas, but basically the same for either one.  Manufacturer's installation instructions must also be followed.
> 
> Generators are regulated by the IMC/IFGC because they are listed under Specific appliances as mtlogcabin said. The IFGC version of that section is 615 and is basically the same as IMC 915.  Whether it sits inside or outside doesn't matter, or air conditioners and rooftop HVAC units wouldn't be covered by code either based on that logic.



I like that opinion!


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## dmal70 (Aug 25, 2020)

jar546 said:


> Do you consider a commercial generator exhaust system a mechanical system as covered by the IMC?


I think according to the prescribed codes, you can consider it as a mechanical system.  But  Single or combined mechanical exhaust systems for environmental air shall be independent of all other exhaust systems. I don't know if i have answered your question. But thought of sharing what i think i knew. Pardon me if it's a huge blunder


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## steveray (Aug 28, 2020)

Which brings you back to NFPA 37...and UL 2200


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