Thread: Don

I have installed a new gas range and am wondering if a double walled exhaust stack is required from the range/oven through the ceiling & attic and roof?

Hello Don
I do not have my code book in front of me but I think not.
Single wall is all that is needed.

Originally Posted by Don Henson

I have installed a new gas range and am wondering if a double walled exhaust stack is required from the range/oven through the ceiling & attic and roof?

As I read what you are asking, you installed a new gas range and are wondering if ... the duct for the exhaust fan ... is required to be double wall, in fact, that duct is required to be a single wall duct.

There is no 'exhaust stack' for a gas range, just an 'exhaust fan duct' if an exhaust fan is installed.

The exhaust fan duct only carries 'environmental air' (the air that you breathe) the same as it would if the range were an electric range, except that the air being exhausted is 'grease laden' from cooking and the duct needs to meet the requirements for that installation: (bold and underlining are mine)
- 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:
- - - (not listing the exceptions as you indicated your gas range is not downdraft)

You don't need any vent or exterior exhaust for a gas range (unless your local Building Department requires one).

If one is installed, then you must follow the applicable rules.

Thanks guys! Very helpful. The unit is a Wolf 4 burner with griddle (16,000/18,000 btu) and I was concerned that it might need double walled pipe. When I test it with all four burners going on High, the exhaust pipe gets rather warm up in the attic - not too hot to hold your hand on, but very warm. I guess it would not be desirable to have double wall pipe because of getting no heat dissipation until reaching the roof line??
Don

Don,
It may be an manufacture installation issue as well as a local code. If the equipment is a commercial unit and not a residential one, the installation is different also design to meet local code comes into effect

When you install a residential appliance you go by one set of standards.
When you install commercial equipment in a residence then you are usually subject to commercial requirements for the installation.

Thanks Gary. It's a residential gas range. I was just kinda thinking backwards I guess on the double wall versus single wall - after all the help from Inspection News I was finally able to resolve it I think.
Appreciate it.
Don

Don, I tell all my clients to exhaust to the outside if at all possible.
Some ethnic groups that cook with a lot of grease do not even want to buy a place with no exhaust to the exterior.

What shocks me is how many developers do not even bother to knock out a hole in back of rangehoods or microhoods even though they are against an exterior wall.

Who wants all that extra grease or moisture ?

So the answer to the second part of your question is they do not need to go through the roof and a back wall may be a much better option.