Thread: Ductless Range Hoods and Over the Stove Microwaves

Hello,

I have two questions here. This pertains to the Boston Mass area, but maybe in your area as well.

The Local Building Inspector has informed us that the listed and labeled ductless range hood needed to be vented directly to the outside. This doesn't make sense to me, and after looking up the IMC code, can not understand why. He also informed us that the over the stove microwave (a different apt) needed to be vented to the outside. I cannot find any codes or amendments in the Boston or Massachusetts codes to validate this.

I haven't heard of this, but maybe you have. Any help would be greatly appreciated.


Sincerely,


Nate


Cite IMC 505.1, IRC 1503.1, and IRC 1504.1

Originally Posted by Nate Postrech

Hello,

I have two questions here. This pertains to the Boston Mass area, but maybe in your area as well.

The Local Building Inspector has informed us that the listed and labeled ductless range hood needed to be vented directly to the outside. This doesn't make sense to me, and after looking up the IMC code, can not understand why. He also informed us that the over the stove microwave (a different apt) needed to be vented to the outside. I cannot find any codes or amendments in the Boston or Massachusetts codes to validate this.

I haven't heard of this, but maybe you have. Any help would be greatly appreciated.


Sincerely,


Nate


Cite IMC 505.1, IRC 1503.1, and IRC 1504.1

Did you ask the municipal inspector what the code citation is on that?

Originally Posted by Jim Luttrall

Did you ask the municipal inspector what the code citation is on that?

I tried getting in touch with him/her but was transferred all over the building dept until they told me he was busy and call back later.

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Also, let me add that I am a Home Inspector for NH working as a finish carpenter in Mass. That's why I'm curious about this.

Are these hoods above gas ranges? He may be right if that is the case.

I don't think I've ever seen a vented hood in an apartment.

Originally Posted by Nate Postrech

Hello,

I have two questions here. This pertains to the Boston Mass area, but maybe in your area as well.

The Local Building Inspector has informed us that the listed and labeled ductless range hood needed to be vented directly to the outside. This doesn't make sense to me, and after looking up the IMC code, can not understand why. He also informed us that the over the stove microwave (a different apt) needed to be vented to the outside. I cannot find any codes or amendments in the Boston or Massachusetts codes to validate this.

I haven't heard of this, but maybe you have. Any help would be greatly appreciated.


Sincerely,


Nate


Cite IMC 505.1, IRC 1503.1, and IRC 1504.1

2009 IMC:

SECTION 505 DOMESTIC KITCHEN EXHAUST EQUIPMENT
505.1 Domestic Systems. Where domestic range hoods and domestic appliances equipped with downdraft exhaust are located within dwelling units, such hoods and appliances shall discharge to the outdoors through sheet metal ducts construccted of galvanized steel, stainless steel, aluminum or copper.. Such ducts shall have smooth innner walls and be air tigh and equipped with a backdrsft damper.
Exceptions:

1. Where installed in accordance with the manufacturer's installations and where mechanical or natural ventilation is otherwise provided in accordance with Chapter 4, listed and labeled ductless range hoods shall not be required to discharge to the outdoors.
2. Ducts for domestic kitchen cooking appliances equipped wih downdraft exhaust systesm shall be permitted to be constructed of shedule 40 PVC pipe and fittings provided that the installation complies with all of the following:

• 2.1 The duct shall be installed under a concrete slab poured on grade.
• 2.2 The underfloor trench in which the duct is installed shall be completely backfilled with sand or gravel.
• 2.3 The PVCduct shall extend not more than 1 inch (25 mm) above the indoor conrete floor surface.
• 2.4 The PVC duct shall extend not more than 1 inch (25 mm) above grade outside of the building.
• 2.5 The PVC ducts shall be solvent cemented.

2009 IRC:

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 shll be equipped wih 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 installations, and where mechanical or natural ventilation is otherwise provided, listed and labeled ductless range hoods shll not be required to discharge to the outdoors.

2009 IRC:

SECTION 1504 INSTALLATION OF MICROWAVE OVENS
M1504.1 Installation of a microwave oven over a cooking appliance. The installation of a listed and lbeled cooking 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 manufcturer's instsllation instuctions. The microwave oven shall conform to UL 923.

Apparently neither kitchen has an operable window nor someother exhaust fan (natural or mechanical ventillation).

You provided the citations in your post.

Very good Mr Watson

I guess if there are no windows in the unit and/or the kitchen is closed off from the rest of the apartment you could say there is no natural ventilation. I would need to see what is going on, but if the kitchen is an open design and there are windows in the next open area, you probably meet the requirements for natural ventilation and can go ductless.

You still need to get it past the AHJ, but you could make a good argument.

Originally Posted by John Kogel

Are these hoods above gas ranges? He may be right if that is the case.

They are gas, but that's not the reason why. Apparently in Mass a multifamily home with 3 or more units is considered commercial, and therefore it is up to the inspector to make the call as to whether or not there should be ducts. The microwaves aren't that bad, because they come with the option to vent them, but a ductless hood needs to be removed/replaced with one that can be ducted. Let's just say the homeowner isn't too happy with all this.

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Apparently neither kitchen has an operable window nor someother exhaust fan (natural or mechanical ventillation).

You provided the citations in your post.

[/QUOTE]

They have two operable windows. And as cited in the codes a listed and labeled ductless hood is ok, and a microwave installed to the manufacturer's specifications is ok. The hood is ductless and the microwave was installed to spec. The microwave has an option to vent to the outside. Also, these are located on inside walls, that's why we went with the the ductless option, as it is unreasonable to duct three stories of separate duct work.

Originally Posted by Mike Kleisch

I guess if there are no windows in the unit and/or the kitchen is closed off from the rest of the apartment you could say there is no natural ventilation. I would need to see what is going on, but if the kitchen is an open design and there are windows in the next open area, you probably meet the requirements for natural ventilation and can go ductless.

You still need to get it past the AHJ, but you could make a good argument.

Plenty of ventilation. two large windows on the adjacent wall. Turns out this property is considered commercial by the state of Mass, so it's a different ball game and up to the inspector to make the call.

Originally Posted by Nate Postrech

Plenty of ventilation. two large windows on the adjacent wall. Turns out this property is considered commercial by the state of Mass, so it's a different ball game and up to the inspector to make the call.

Chapter 4 of the IMC states that the opening of a window needs to be 4 percent of the floor area for natural ventilation. It seems to me that if you meet that requirement than you should be ok. I would politely discuss this with the building inspector.

Originally Posted by Mark Reinmiller

Chapter 4 of the IMC states that the opening of a window needs to be 4 percent of the floor area for natural ventilation. It seems to me that if you meet that requirement than you should be ok. I would politely discuss this with the building inspector.

I would say these windows are around 30" w by 54" h double hung. I poured over the codes last night trying to find why this guy failed us on the inspection.

On a side note, I didn't find any code requiring an over the stove microwave or hood. If it was up to me, put the microwave on the counter and open a window if it gets too hot baking thanksgiving dinner.

met the inspector today and he quoted the same codes I did...but left out the exemptions and section 402.1 and 402.2. Wish my name was on the side of the truck, because he's costing the company big money for nothing.

Did you bring up the exemptions? You might have an inspector that will give you the part of the code he wants enforced, unless you bring up the exemption he will say nothing more.

Originally Posted by Mike Kleisch

Did you bring up the exemptions? You might have an inspector that will give you the part of the code he wants enforced, unless you bring up the exemption he will say nothing more.

Yes, or I tried. The work is almost done, so I guess it's a moot point now. Good information for the future, though.