Thread: Legal W/H Duct

I have seen a flexible duct on a hot water heater that I am not familiar with. It looks like it is manufactured for this purpose but still resembles a flex dryer vent. Is it legal?

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Looks like a flexible flue-liner to me. I'll defer to others about 'legality'.

Oh, and expect to get slammed for calling it a duct!!

Not correct as installed. Incorrect (too long) length, unsupported, kinked, sagging, insufficient vent(connector) RISE, incorrect transitions, wrong adapter & incorrect transition to rigid type b-vent. Can't make out details in photo but appears to be upside down (male end at hood, female at rigid vent above, if so that's upside down - I'm having d/l and magnifiction viewing issues on this end) and lacking further support, transition & f/s support at ceiling.

Looks to be DIY using incorrect materials of product such as attached slip sheet file (pdf) below. Note varying lengths with premanufactured ends to be used with proper transitions & adapter fittings as a part of the listed mfg. instructions/specifications.

The Cat I WH with draft hood installation in the ininsulted, unconditioned garage with insufficient clearances airspaces, combustibles, etc. for single wall vent connector at draft hood (not appropriate for this unconditoned space) should be vented with B-vent type system or better from draft hood transition on up, with proper offsets, supports, fire stops, as specified by the system mfg.

Generally offsets for vertical venting shouldn't exceed 15 rad. Minimum height above hood prior to offset. The area above WH for its entire diameter when Cat I with draft hood is a zone to remain clear for air space and all combustibles for a height clearance. SW vent connectors and draft hoods require an air space clearance spelled out in the fuel gas and venting, mechanical, and plumbing code sections depending on the jurisdiction. Reductions in vent connectors & venting not permitted. Use of proper mfg. system fittings, transitions, connections required - wrong adapter fitting at male end.

Doubful draft, likely spillage. Not correct in application & execution/installation of materials.

I think the installation could have been done a little more neatly but I wouldn't flag it. I would call the support adequate as well because it is a pretty short run.

JMO

Its too long been accordian-style "smushed" and is not supported at all for any of the multiple axis changes in direction, and effectively trapping and lateral for gravity drafting. Spillage of CO and products of combustion, ineffective draft, etc.

When you have a 3" outlet drafthood you need a transition fitting to 4" venting you don't just grab a 4" SW vent connector and "smush" & crimp it to same.

Mr. Watson makes some good points. If the flex vent were properly sized and installed it would not necessarily need extra support. Though the rigid would. Our area inspectors would fail it for workmanship. Definitely upside down. But, hey the crown moulding sure is elegant.

Originally Posted by Mark Fisher

"...Oh, and expect to get slammed for calling it a duct!!

Lol....!

Looks like Metal-Fab B-Flex.

The actual interior diameter of the vent for design and specification proposes is the same as the connector size.

It's common to find these vents bent in that manner as the connectors are factory attached to pre-cut lengths of flex-vent, and the excess length has to go somewhere. As long as there is a continuous rise, and no actual deformation of the vent at the bends, the Metal-Fab instructions seem to allow it.

Can't tell from the picture, but the required clearance / thimble / fire stop may not be present where the transition to rigid B-Vent passes thought the ceiling.

In the future when you see venting you believe may be questionable it helps to take a picture of the labeling, you can then refer to this when you get back to the office to research the manufacturer and installation requirements.

This being a single-wall vent, doesn't it need 6 inches clearance to combustibles? How combustible is that black foam on the water pipe?
MB

Originally Posted by Matt Bezanson

This being a single-wall vent, doesn't it need 6 inches clearance to combustibles? How combustible is that black foam on the water pipe?
MB

Follow the link in the post #8 below, its double-wall, just like any other B-Vent.

The link M.T. offered in post #8 is to the same (b-flex) document I uploaded and attached in post 3.

The draft hood and the SW attached to same prior to the b-flex require clearance.

The top area at and above a cat-I draft-hood equipped storage type WH requires air space (and combustible) clearances for the circum. of its jacket and above same even when same is directly B-vented, and is part of reason for a minimal vertical rise before offset immediately above and around the venting (b-vent, b-flex, SW, transition fittings, etc.) or vent connections from same.

Originally Posted by William Cline

Definitely upside down.

William,

What feature of the vent assembly are you using to determine the incorrect vent orientation?

- Thanks

Originally Posted by Michael Thomas

William,

What feature of the vent assembly are you using to determine the incorrect vent orientation?

- Thanks

Michael,

The male end is down. If you look closely at the photo you will see the twist-lock grooves (indentations) which match up with whatever is installed over it (adapter or adjustable length vent). The female twist-lock end is up.

In the photo you can see the indentations of the twist-lock male end are on the end which is down. The photo is such that the top is not clear enough to see the grooves are projecting outward instead of inward.

It also looks like that is bent too sharply and the inner and outer pieces are likely touching each other.

Thanks much. You guys are great!(as always) I appreciate all of the info and advice.