Flex duct for vent

[rlskfoster]

New home today has a Hotpoint Microwave/Range Hood Combo.

The transition piece was the silver metallic material you see on some dryer transitions. It almost feels like cloth and very flexible. Manufacturers instructions sitting on counter did not specifically identify a type of material to use as a transition, but, it has a picture of a 90 degree elbow. What is the general consensus for this material to be used in this application.I have seen the metal flex duct used for a short transition and found literature to support its use for short transitions, but I am unsure about this.

Here is the picture:

Buster

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[hausdok]

Hi,

It's a heated location, it's short and they won't be pushing any lint up through it, so it's never going to get clogged. As long as there's a damper in the micowave/fan exhaust outlet it should be fine.

OT - OF!!!

M.

[kurt]

What would grease do in that stuff? I'm not saying it's bad and I'm not saying it's good; I'm just curious.

Personally, if I was going cheapo & using flex, I'd get the semi rigid dryer duct (you know, the expando stuff....) Actually, I can think of about a dozen better materials & methods for that little elbow; the installer is a maroon.

[Les]

My two cents worth - that sure looks like

Mylar and is worthless for any application, wheather 6" or 6'. It will fail in this application is my world famous opinion.

So there!

[Mike Lamb]

SECTION M1502

RANGE HOODS

M1502.1 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.

M1502.2 Duct material.

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

[kurt]

Well, that stuff doesn't have a smooth interior surface. But, it doesn't say you can't use flex either.

Come to think of it, I've been in some nasty Section 8 crawlers where they've used flex, and it was greased out.

I'm w/Les. Stuffs gonna shitcan.

[Bill Kibbel]

Thanks to Mike L. for pointing us to M1502. The smooth interior of a steel or copper duct makes sense to me.

Some families' ethnic culinary practices can load the duct with grease in a short amount of time. All that grease is directly above where people frequently leave things that can easily ignite over an open flame.

Sometimes I need to remind my wife that the smoke detector is not the timer that lets you know it's done.

[kurt]

Originally posted by inspecthistoric

Sometimes I need to remind my wife that the smoke detector is not the timer that lets you know it's done.

[:-bonc01] Good one...

[swolsen]

I agree with Mike, that looks like Mylar and should not be used in that application.

[will5443]

That pipe should be UL listed. If it is not, it needs to be changed. There should be a sticker on the pipe, unless the pipe has been cut. Have them verify the listing. If they cant, change the pipe.

[Bain]

You guys are just plain stupid. A licensed HVAC dude used Mylar for a furnace flue pipe, so Mylar has to be okay for a range hood duct. Les, what were you thinking?

John

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[Les]

It was a momentary lapse of my insanity!!