On several previous treads, people have stated a 12 inch straight length of flue pipe is needed on top of the draft hood. I have asked on two different threads for someone to point out the code requirement or manufactures requirements. Both times, there were no answers.

Last night I sent an e-mail to A.O Smith asking that question, the following is their reply:

DISCUSSION THREAD
Response (Brandon Freeman) 05/23/2007 08:59 AM
Darren,

Thank you for contacting us. If you are referring to standard atmospheric venting water heaters, then a straight vent run is not a requirement before a bend, although we do recommend it as it allows for better venting. The main thing to insure is that any horizontal run is on an appropriate rise and that the total horizontal is less than 75% of the vertical. Please let us know if we can assist you further.

Sincerely,
Brandon



So, unless someone can show some code requirement, let's put this HI folk-lore to bed right now!


Darren

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Darren,

Thanks for this. I too have asked about this from local HVA/C technicians and have received a puzzled look. It will be interesting to hear the responses.

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Instead of sending that to the water heater manufacturer, send it to the vent manufacturer.

THEY (the vent manufacturer) are the ones which state and show going vertical 1 foot before turning, and that one foot, to may recollection, is measured from the top of the water heater, not from the top of the draft hood (at least as I remember the drawings showing it).

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Jerry Peck, Construction / Litigation Consultant
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Jerry

Show me the proof;

Show me code requirements

Show me manufactures requirements

Show me show me show me

I would think the water heater manufacture whould require it if neededl they said NO.

Show me


Darren

Water heater manufacturers send out atmospheric appliances with draft hoods on them, this tells me a lot about the manufacturers.

A one foot section of straight vent doesn't make an appliance vent better, where do they get this stuff?

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Measured Performance more than just a buzzword

Darren,

I just reviewed the installation instructions from three B vent manufacturers.

DuraVent:
"Connector Rise. Plan a minimum of one foot vertical connector rise
coming out of each appliance."

AmeriVent:
"Wherever possible, install vertical vents directly above
appliances before beginning any lateral runs. "

And I could find no such requirements for MetalBestos.

But, then again, I could very well have missed the specific instruction.

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I tried to attach this with my post, but my notebook computer kept crashing (I'm out of town and I suspect it does not like the motel's wireless system ).

From the Simpson installation instructions: see attached - read #8 right there at the top.

Attached Images

Simpson_L204A_apr00_1-foot_minimum_connector_rise.pdf (23.8 KB, 89 views)

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Jerry Peck, Construction / Litigation Consultant
Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
EastWestData (www.EastWestData.com )

Jerry,

You of all people surprise me.

Everyone knows when reading a code book what the word 'shall' means.

When reading your attachment, there is a big difference between 'Plan' and 'Shall'.

Installation instructions usually include "must"; as in
"there must be a 12 inch rise before any bends can be installed".

I take your instructions as, "plan on 12 inches, but if you don't have it, no problem."

Or take Gunnar quote, "whenever possible" doesn't mean MUST.


Darren

Oh, yeah. One other thing. Regarding the required draft hood connector. In my area, I never see one. In the AmeriVent instructions, the draft hood connector is listed as optional.

AmeriVent Products
(click on the diagrams, specifically "Type B Gas Vent Single Appliance")

On the same page is a link to download the installation instructions and the item that I quoted is at the bottom of p. 2.

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What is the circumference of a moose?

Darren,

Does *THIS* "SHALL" mean anything to you?

From the IRC. (bold and underlining are mine).

- M1307.1 General. Installation of appliances shall conform to the conditions of their listing and label and the manufacturer’s installation instructions. The manufacturer’s operating and installation instructions shall remain attached to the appliance.

That means *YOU SHALL* follow the manufacturer's installation instructions and *YOU HAD BETTER PLAN ON* that minimum height of 12".



I have no idea why you insist on being so confused on this, and then continue trying to defend your position on it.

__________________
Jerry Peck, Construction / Litigation Consultant
Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
EastWestData (www.EastWestData.com )

Jerry,

I kind of have to agree with Darren. One B-vent product instructions (DuraVent) uses ambiguous wording, one product (AmeriVent) writes "whenever possible" and another (MetalBestos) does not mention it at all. This apparently means that we must know all of the installation instructions of all of the B-vent manufacturers in order to properly report on them.

Either that, or we defer on everything.

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What is the circumference of a moose?

[quote=Jerry Peck;6677]Darren,

Does *THIS* "SHALL" mean anything to you?

From the IRC. (bold and underlining are mine).

- M1307.1 General. Installation of appliances shall conform to the conditions of their listing and label and the manufacturer’s installation instructions. The manufacturer’s operating and installation instructions shall remain attached to the appliance.


OK then, is a vent considered an appliance; I think not.


Sorry Jerry, you're making this up as you go.......


Darren

Ever use a double-basin sink where the drains are connected with a tee directly under one of the drains? That is, the straight part of the tee is vertical? The difference in draining speed is very great. The push for water's draining is the same as the push for hot air's tendency to go up the vent, its weight, where the hot air has negative weight. The push is greatest when the flow is aligned with gravity, vertical. This, of course, is why the amount of horizontal travel in a atmospherically-vented vent is limited. The only reason the combustion gases are moving up the vent is that they are marginally lighter than the surrounding air. It doesn't take a whole lot to screw this up and have some of the combustion gases come out the huge hole at the draft hood. So as the combustion gases pass out of the appliance, through the draft hood, and into the vent, we want as much push, with as little friction, as possible. A bend, going into a section that is not vertical, right above the draft hood, will make the upward draft force less than what it would be with a straight, vertical section. Maybe it is a small difference, but when outside winds are set up for backdrafting, or if the combustion air is insufficient, I wouldn't want venting system slowing down the combustion gases just where they can come out into the room.

So I believe that is why there are reccommendations for a straight section of pipe above the draft hood.

They may be only recommendations, but if an installation doesn't start out with a straight section of vent where it could, I would call it out. There are advantages in our not being code inspectors. We can, and should, point out where safety could be improved even if the installation meets code. If I were acting for the AHJ I would require a straight section at the draft hood if the installation allowed it based on the installation instructions mentioned in this thread.

- BOB

Bob:

OK; you do an inspection and call out a water heater vent needs a straight section of pipe attached to the draft hood.

The seller then calls a licensed plumber who tells her, the inspector is wrong, It is not a code issue; manufactures RECOMMEND it be installed this way but it's not REQUIRED. She then calls her local AHJ who backs up the plumber.

Oh, by the way, here's my bill for a $175.00 service call.

Seller then calls you looking for $175.00 because you believe in the HI foke lore.

Hey; I'm all for calling ANYTHING out if it's wrong. However, I need back-up, (code requirements or manufactures REQUIREMENTS, not suggestions).


Darren

Perhaps I wasn't long-winded enough in my post. I do not believe in the HI folklore, I believe in the laws of fluid flow and thermodynamics.

From Gunner's post:
AmeriVent:
"Wherever possible, install vertical vents directly above
appliances before beginning any lateral runs. "

Some of the vent manufacturers give what could be called a recommendation or preference for putting a straight vent section above the draft hood. I explained (or tried to) why this is A Good Thing.

The issue you make of the financial liability is a good one, and I did not think of it. I would still call it out, as a recommendation, in the case where having a vertical section is possible, but I would explicitly say that the code "probably" does not require it.

You make an important distinction between requirements and recommendations. I believe that the recommendation is significant enough to mention, and, thanks to your post, I would make it clear that it is a recommendation and not a requirement. I can understand if another inspector would not mention it at all.

- BOB

Darren,

You are beginning to sound a bit like Tony M. here.

You do not need, should not need, code, HIs *CANNOT* *MAKE* anyone do anything.

Are you forgetting that you are being paid to provide *YOUR* "professional opinion"?

*MY* "Professional Opinion" *IS NOT* going to contradict the manufacturers opinion.

If the manufacturer wants (however they word it) something to make something work better, *I* am not going to take it upon myself to say it is not needed.

I inspected under that concept for over 16 years and NOT ONCE has any seller ended up trying to get me to pay for THEIR (their contractor's, their whomever) errors. The manufacturer wants it, I recommend it, I cannot not (as an HI) make anyone do anything.

I guess you just don't get the mileage with the way you present your information that I got with the way I presented my information.

My clients understand that what there are reasons why the manufacturers want what they want, maybe yours don't?

Bob H. recently, on another thread (which it appears you missed) addressed this very issue, providing the listing information (or something, forgot now) which addresses the very issue you are trying to skirt - maybe Bob will post it again.

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Jerry Peck, Construction / Litigation Consultant
Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
EastWestData (www.EastWestData.com )

Darren,

You've made a very defensible argument with respect to code. I have not been able to find the 12 inch requirement in any resources I have checked. I am unable to defend what I have been saying for a very long time. I hate you, Darren.

I do not have the 2002 NFGC, so I can't check their tables to see what they have to say. If you or any respondent on the thread have a copy will you look and report if the tables refer to this subject of length?

I do remember learning it in a CE course early in my licensed career and I remember it being recommended because of the inefficiencies of heaters and the bends closer than 12 inches having a tendecy to corrode prematurely.

Let's hear from some plumbers on this issue. And as for Inspectors, what does your local code say?

For a different take on the use of single wall pipe AT ALL, read this article.
GAS VENT DESIGN

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Jerry,

You are correct; HI cannot make anyone DO anything. The best we can do is offer our opinion and provide proper back-up to support our opinion.

Now, rumor has it you are now in (building) code enforcment. Here in NJ, a building inspector is responsible for many areas of the mechanical code.

A building inspector would (should) never fail an inspection because a manufacture states "whenever possible" in their installation guide. Here in NJ, a contractor has the right to appeal an inspector's decision. If it's found the inspector is wrong, disipline actions (possible lose of license) can be taken.

On another note, when I was a superintendent, I had a sub contractor dispute my call for his installation of modulines in the ceiling. He stated he "installed 50,000 modulines this way" just because you did it that way for years doesn't make it right.

See Thom's post above; he's thinking about what he's been saying for years now. He believes he could be wrong. If someone calls him out right now, he has no back-up to prove his call. Maybe he'll find something, maybe he won't. Until someone can show me where a manufacture of a water heater REQUIRES a straight pipe on the draft hood, it's a myth.

An stop comparing me to other people; any good home inspector needs back-up to prove their claim. Without back-up, your creating more HI folk lore.


Darren