Range Hoods and Exhaust Ducts

[Ben J. Gromicko]

Using the following for reference: http://publicecodes.citation.com/ico..._15_sec003.htm

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, shall be equipped with a back-draft damper, and shall be independent of all other exhaust systems. 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.

Single-wall ducts serving range hoods shall be constructed of galvanized steel, stainless steel or copper. 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 M1507.4.

Exhaust hood systems capable of exhausting in excess of 400 cubic feet per minute (0.19 m3/s) shall be provided with makeup air at a rate approximately equal to the exhaust air rate. Such makeup air systems shall be equipped with a means of closure and shall be automatically controlled to start and operate simultaneously with the exhaust system.

TABLE M1507.4 MINIMUM REQUIRED LOCAL EXHAUST RATES FOR ONE- AND TWO-FAMILY DWELLINGS

AREA TO BE EXHAUSTED EXHAUST RATES Kitchens 100 cfm intermittent or 25 cfm continuous Bathrooms-Toilet Rooms Mechanical exhaust capacity of 50 cfm intermittent or 20 cfm continuous
For SI: 1 cubic foot per minute = 0.0004719 m3/s.

QUESTION: All that is REGARDLESS of the fuel-type of the range appliance - Correct? A gas range appliance should have an exhaust hood that discharges outside, just like an electrical range appliance should.

Agree?

[Michael Larson]

I recommend the installation of an exterior venting exhaust hood in all cases apart from any code.

Often my clients were unaware that the hood did not exhaust to the exterior of the building.

[Joe Funderburk, CMI]

Note this code and commentary:

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 M1507.3.

Commentary: This section does not require installation of a hood that
exhausts to the outdoors for domestic kitchen cooking
appliances. It only provides guidance for sizing the
exhaust fans for hoods that do exhaust to the outdoors.
Mechanical ventilation would be required only
where natural ventilation is not provided (see Section
R303).

Other than the code I'm pasting below, I'm not aware of a code that requires a range hood of any type at all in a one or two family dwelling or townhome, although range manufacturer's recommend them (I think) and I definitely put it in my report if one is not present. If you do install a range hood, then the text you cited applies regardless of the fuel type.

OVERHEAD EXHAUST HOODS
M1505.1 General. Domestic open-top broiler units shall have
a metal exhaust hood, having a minimum thickness of
0.0157-inch (0.3950 mm) (No. 28 gage) with 1/4 inch (6.4 mm)
clearance 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, extend over the entire unit, discharge to the
outdoors and be equipped with a backdraft damper or other
means to control infiltration/exfiltration when not in operation.
Broiler units incorporating an integral exhaust system, and
listed and labeled for use without an exhaust hood, need not
have an exhaust hood.

[Joseph W. Keresztury]

Ben, I hope it's OK that I paste our emails here, to add further detail, since that's what originated this.
Any help from all will be appreciated.
Mike, agreed. I have been recommending venting to the exterior on numerous new home warranty inspections with gas cooktops in the same developement, qouting from a InterNACHI course I took. The numerous clients are now asking for back up info/code for it.

Original correspondence with Ben:
Hey Ben,
Here is a qoute from one of your Nachi courses (don't remember which one) that I have been qouting to clients that have gas cooktops but not vented to exterior.
I call it out as a qoute from the InterNational Association of Certified Home inspectors:
"Remember when evaluating homes with gas ranges or cook tops that gas code requires they be vented to the building exterior through a hard-ducted vent. Re circulating models do not satisfy the code requirement."
I have numerous clients in a neighborhood that I noted this on their builders warranty inspection and are asking for backup to this opinion to get builder to correct this. Where you qouting this from IRC or what Gas code source. Where can I better review this at? Any info would be a big help. Even a code reference number.
I enjoy all your courses and videos. Great job.
Thanx, Joe

Joe,
Slam dunk.
Here you go: IRC. Chapter 15. Exhaust Systems. Section M1503. Range Hoods.
Hope that helps.
Sincerely,
BEN GROMICKO

Hey Ben, thanx for the response. But that (IRC) doesn't really help back up the above qoute that I have been using with clients. The IRC 2006 M1503 section doesn't even differentiate from electric or gas range for venting and it has the exception of ductless vent a hoods 'shall not be required to discharge outdoors.' per manufacturers. So the IRC doesn't help with the statement I got from the InterNACHI course and have been qouting. -
"Remember when evaluating homes with gas ranges or cook tops that gas code requires they be vented to the building exterior through a hard-ducted vent. Re circulating models do not satisfy the code requirement".
So is there any back up to this statement that says gas code requires gas ranges be vented to outside? For instance the National Fuel Gas Code, International Gas Code, Fire Protection Agency, etc.? I thought I had seen something on it before but can't remember where. I have clients wanting more info on it.
Thanx for any further help.
Joe

Joe,
Understood.
Let's ask here - and please join in - https://www.nachi.org/forum/f18/range...64/#post874927
Sincerely,
BEN GROMICKO

[Michael Larson]

I do not cite code.

I recommend installation of a exhaust hood to improve indoor air quality regardless of a gas or electric cook top.

It really depends on how the owner cooks.

It's up to them.

Unless you are a code enforcement official you are biting more off than you can chew.

You are paid to offer your opinion and recommendations.

[Ben J. Gromicko]

It seems clear from the following:

SECTION M1503 RANGE HOODS

M1503.1 General.
Range hoods shall discharge to the outdoors through a single-wall duct.

If an inspector sees a range hood (installed over a range appliance in the kitchen), then it must discharge outside. (Let's say... according to best practice techniques)
Clear? No?

[Michael Larson]

Originally Posted by bgromicko

It seems clear from the following:

SECTION M1503 RANGE HOODS

M1503.1 General.
Range hoods shall discharge to the outdoors through a single-wall duct.

If an inspector sees a range hood (installed over a range appliance in the kitchen), then it must discharge outside. (Let's say... according to best practice techniques)
Clear? No?

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.

http://publicecodes.citation.com/ico..._15_sec003.htm

[Ben J. Gromicko]

Augh.

It seems clear from the following:

SECTION M1503 RANGE HOODS

M1503.1 General.
Range hoods shall discharge to the outdoors through a single-wall duct. There is an exception to this rule.

If an inspector sees a range hood (installed over a range appliance in the kitchen), then it must discharge outside. (Let's say... according to best practice techniques)
Clear? No?

[Michael Larson]

Ben, the exception is very clear. If designed as such it is a listed vnent hood is DOES NOT REQUIRE exterior venting

Why dance about this?

I make my recommendation apart from what the code says.

[Joe Funderburk, CMI]

Originally Posted by mlarson

I recommend the installation of an exterior venting exhaust hood in all cases apart from any code.

How do you do that in a slab home when the range is not on an exterior wall?

There is no reason to call a re-circulating range hood a defect unless it's a broiler ('jenn-air' type range). I simply identify the the type of hood (re-circulating, or exhaust system).

[Joseph W. Keresztury]

Originally Posted by mlarson

I do not cite code.

I recommend installation of a exhaust hood to improve indoor air quality regardless of a gas or electric cook top.

It really depends on how the owner cooks.

It's up to them.
It's really not up to the owner yet at this point since they are looking to the builder for correction.

Unless you are a code enforcement official you are biting more off than you can chew.
I have explained to the buyer that I am not a code compliance inspector.

You are paid to offer your opinion and recommendations.
Mike, That's what I did, offer my opinion and recommendation and qouted from a Nachi educational course. The qoute now appears not to have backup to it.

----

[Bob Elliott, 450.0002662]

No highrise will allow exterior venting to be retro-fit.
Case closed /rebutal is fruitless.

[Joseph W. Keresztury]

Originally Posted by bgromicko

It seems clear from the following:

SECTION M1503 RANGE HOODS

M1503.1 General.
Range hoods shall discharge to the outdoors through a single-wall duct.

If an inspector sees a range hood (installed over a range appliance in the kitchen), then it must discharge outside. (Let's say... according to best practice techniques)
Clear? No?

Ben, I see Mike already beat me to it.
As I mentioned in my email and he qoutes here. In the IRC M1503 there is an exception based on manufacturers instructions.
...... your qoute - 'according to best practices' makes more sense now than what I was qouting from the course here. But I already used that qoute which apparently is inaccurate. Basically I will have to be correcting myself to numerous clients.

[Joe Funderburk, CMI]

Originally Posted by bgromicko

Augh.

It seems clear from the following:

SECTION M1503 RANGE HOODS

M1503.1 General.
Range hoods shall discharge to the outdoors through a single-wall duct. There is an exception to this rule.

Rule of basic transportation: you have to fly in a plane to get from Chicago to Miami.

Exception 1: you can drive a car if you want to.

Commentary: driving is not wrong, but flying may be considered 'better'. It's often just a matter of economics.

[Robert A. Wilson]

It is not unusual to find co levels of 200PPM at the top of a gas range when the oven is on. I always recommend outside exhaust with a gas range