This vent pipe is connected directly to the exterior of the building. Is the pipe material okay, or should it be smooth wall galvanized steel, stainless steel, or copper? The NFPA recommends this type of material over open topped broiler in residential applications. Does a stove fall under the category of open topped broiler?
The coil needs to be stretched according to proper practice of the flex hose. I would mention this and explain why there is a problem with the installation.
the problem is the duct material is not allowed with either exhaust system no matter how far you stretch it or how neatly it’s installed
SECTION M1503
RANGE HOODS
M1503.1 General. Range hoods shall discharge to the outdoors
through a single-wall duct. The duct serving the hood
shall have a smooth interior surface, shall be air tight and shall
be equipped with a backdraft damper. Ducts serving range
hoods shall not terminate in an attic or crawl space or areas
inside the building.
Exception: Where installed in accordance with the manufacturer’s
installation instructions, and where mechanical or
natural ventilation is otherwise provided, listed and labeled
ductless range hoods shall not be required to discharge to
the outdoors.
M1503.2 Duct material. Single-wall ducts serving range
hoods shall be constructed of galvanized steel, stainless steel or
copper.
Exception: Ducts for domestic kitchen cooking appliances
equipped with down-draft exhaust systems shall be permitted
to be constructed of schedule 40 PVC pipe provided that
the installation complies with all of the following:
- The duct shall be installed under a concrete slab
poured on grade; and - The underfloor trench in which the duct is installed
shall be completely backfilled with sand or gravel; and - The PVC duct shall extend not more than 1 inch (25
mm) above the indoor concrete floor surface; and - The PVC duct shall extend not more than 1 inch (25
mm) above grade outside of the building; and - The PVC ducts shall be solvent cemented.
M1503.3 Kitchen exhaust rates. Where domestic kitchen
cooking appliances are equipped with ducted range hoods or
down-draft exhaust systems, the fans shall be sized in accordance
with Section MI507.3.
SECTION M1504
INSTALLATION OF MICROWAVE OVENS
M1504.1 Installation of microwave oven over a cooking
appliance. The installation of a listed and labeled cooking
335
EXHAUST SYSTEMS
appliance or microwave oven over a listed and labeled cooking
appliance shall conform to the terms of the upper appliance’s
listing and label and the manufacturer’s installation instructions.
The microwave oven shall conform to UL 923.
SECTION M1505
OVERHEAD EXHAUST HOODS
M1505.1 General. Domestic open-top broiler units shall be
provided with a metal exhaust hood, not less than 28 gage, with
1/4 inch (6 mm) between the hood and the underside of combustible
material or cabinets. A clearance of at least 24 inches (610
mm) shall be maintained between the cooking surface and the
combustible material or cabinet. The hood shall be at least as
wide as the broiler unit and shall extend over the entire unit.
Such exhaust hood shall discharge to the outdoors and shall be
equipped with a backdraft damper or other means to control
infiltrationlexfiltration when not in operation. Broiler units
incorporating an integral exhaust system, and listed and
labeled for use without an exhaust hood, need not be provided
with an exhaust hood.
SECTION M1506
EXHAUST DUCTS
M1506.1 Ducts. Where exhaust duct construction is not specified
in this chapter, such construction shall comply with Chapter
Barry, what code is it that you are referencing?
International Mechanical Code
John it does not matter what code it is we can only recommend what was OK at the time. I do not agree to leave it like this and once you mention it needs to be stretched we hope that the person they call will correct it properly. We can say it would be best if it was solid metal according to proper practice today. M1506.1 Ducts. Where exhaust duct construction is not specified
in this chapter, such construction shall comply with Chapter
16. This is from the IRC 2006 also.
I reported it does not meet current standards and may not be as safe as current standard material and installation practice. Thanks for the help.
2012 irc it’s basically the same in all previous versions
corrugated or accordion style is not smooth wall, “gunk” (inspectorspeak) will build up on the ridges/irregularities and become a combustion-fire hazard, therefore not allowed for this application
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I should also mention that a manufacturer is making flex duct fire proof!
That being said Yes I would agree with the grease problem as Barry is pointed out.
where is it allowed in 16
i’m not saying the code has to be quoted in a report but knowing what is not allowed is an automatic noted deficiency that requires removal and replacement with proper materials
any less is just another logo certified soft report
looks like the jiffy pop exploded…
I was referring to the design of the duct in question. It is designed to be stretched in the manufactured installation guidelines. I was not saying that this is acceptable.
M1503.1 General.
The AHJ may allow it and this is sad but that is why we are in this business. This could be an outside wall side exhaust hood that presents no danger.
I disagree.
Slinkys are a grease trap.
The client needs to be made aware of the potential hazard and that they can not be cleaned.
My non CMI opinion of course. 
That makes about as much sense to me as the need to “stretch it out more”…
But then I’m not a CMI either!
Look at what I’ve been missing all these years!?
You have to have 26ga metal duct go through the garage wall to your HVAC equipment, but “foil” duct is OK directly above the stove…
I did not say it was OK!
You said:
:roll:
Changed just for you!
The coil needs to be stretched according to proper practice of the flex hose. I would mention this and explain why there is a problem with the installation.
Please explain where one goes to find in writing the “proper practice” for installation of flex “hose” and exactly how much stretching is required for a range hood?
HRAI
If you would write that, or similar, in a report in my area you wouldn’t stay in business very long.