Thread: Combustable exhaust slope

What is the slope supposed to be on a connector vent pipe of a hot water heater (nat gas)? Also is there suppose to be a a minimum rise of vent pipe above the draft hood before an elbow?

Similar Threads:

• Condensate leak at furnace exhaust
• new construction - exhaust vent quest.
• White "powder" at furnace exhaust tube
• bath fans, exhaust to exterior
• That dread Exhaust Vent - Texas gang

Originally Posted by Dave Taurinskas

What is the slope supposed to be on a connector vent pipe of a hot water heater (nat gas)?

1/4 inch per foot slope

Also is there suppose to be a a minimum rise of vent pipe above the draft hood before an elbow?

1 foot rise minimum

Quote:

Also is there suppose to be a a minimum rise of vent pipe above the draft hood before an elbow?

1 foot rise minimum

Hmmmmmm.............. Code cite please Jerry (or prove that all manufacturers installation instructions call for it)

Originally Posted by Brandon Whitmore

Hmmmmmm.............. Code cite please Jerry (or prove that all manufacturers installation instructions call for it)

I'll give one a code section and one manufacturer, you can look the rest up.

From the 2006 IRC.

- G2427.6.1 (503.6.1) Installation, general.

Gas vents shall be installed in accordance with the terms of their listings and the manufacturer’s instructions.

Go here: ( Simpson Dura-vent ), scroll down to 'installation instructions (pdf), select 'Type B Gas Vent (round), click 'Go', the installation instructions will load as a pdf.

Scroll down to page 3, read 6.: (red text is mine)

6. Slope. If the venting system contains lateral (horizontal) components, they shall be positioned so they have an upwards slope away from the appliance of not less than 1/4-inch rise per foot of run. (Horizontal vent installed in attics, unconditioned area, or between floors have further restrictions, please consult your local building codes for specific limitations.)

Now scroll down to page 4, read 8.: (red text IS THEIRS)
8. Connector Rise. Plan a minimum of one foot vertical connector rise coming out of each appliance.

I believe that covers both questions being asked.

Jerry,

Would you be so kind as to show me where I am missing that requirement in these instructions : http://www.americanmetalproducts.com...0AmeriVent.pdf

Thanks.

Interesting selection/choice to quote Bvent for the draft-hood connector.

More common to see single wall from draft hood as a connector to bvent.

Consult first the Manufacturer of the water heater (supplying draft hood) instructions. Many times those instructions additionally reference NFPA 54's National Fuel Gas Code. If restrictions, clearances, etc. are more restrictive in the manufacturer's instructions (possibly incorporating National Fuel Gas Code) then they would have to be abided. One can compare the mfg date and instructions date to the edition of NFPA 54 (National Fuel Gas Code) and compare.

NFPA's publications are available to view and read on line for free.

It would further depend on what code adoptions were applicable (with whatever ammendments).

The most restrictive applicable would apply (the greater rise per foot) - it depends.

P.S. it always makes me nervous when an elbow (instead of offset/s) is/are mentioned concerning gas vents. Higher efficiency natural gas water heater?

Oh god.... here we go. Wasn't there a 200 page thread about this a couple years ago?

[QUOTE][Oh god.... here we go. Wasn't there a 200 page thread about this a couple years ago?/QUOTE]

Hence, the smiley faces.

Originally Posted by Brandon Whitmore

Jerry,

Would you be so kind as to show me where I am missing that requirement in these instructions : http://www.americanmetalproducts.com...0AmeriVent.pdf

Thanks.

Brandon,

No, but I can this one: (which is also for Amerivent and is also from 2006)

http://www.ampcostacks.com/pdfs/bven...structions.pdf

Page 2, General Installation Guidelines, 8.:

- 8.

Maintain a pitch or rise from the appliance to the vent cap on horizontal runs. The pitch shall not be less than ¼ inch to the foot.

Regarding the 1 foot minimum rise before the first elbow to horizontal, Bob Harper posted an NFPA 54 reference on that thread which Matt is referencing in:

Oh god.... here we go. Wasn't there a 200 page thread about this a couple years ago?

Bob, are you out there? I'll have to copy that information this time, I either forgot to last time or forgot where I put it.

Here's instructions for AmeriFlex (common, at least in this area) : http://www.americanmetalproducts.com...stall/flex.pdf

I'm back from the HPBA EXPO in Reno.

1/4" per ft. sloping up towards the breeching.

As for the 1 ft rise, it is not a clear code requirement per se. Here's how you arrive at it:
First of all, the sizing charts in the IFGC begin with a 1ft rise for vent diameters up to 12", where it starts at 2ft. You must look up your minimum vent height for a given setup. For instance, a 100,000 BTU/hr natural vented appliance with a 5" draft hood would need a 50ft. vent height if there is only a 12" vent connector rise. However, if you provide a 24" rise, you only need a20ft. vent height and a 36" rise would require only an 8ft. vent height. See the effect of vent connector rise? It is a practical matter. Putting an elbow directly on a draft hood is just begging for it to spill fumes into the building.

The code does force some practical considerations on you. If you really ran it through, you'd probably find some other reductions such as lateral offset, extra ells, corrugated liner, etc.
HTH,
Bob

Bob,

Thank you.

I looked at that vent connector height but said to myself that was not what you used before, that it was an NFPA 54 reference ... possibly the reason I did not copy your post before was because I it was in the code, only I forget how to get there from the code.

Thank you again.

Bob,

I copied it, make some minor editorial changes, and made it into a pdf.

Does it look good to you?

Originally Posted by Jerry Peck

Bob,

I copied it, make some minor editorial changes, and made it into a pdf.

Does it look good to you?

This doesn't only apply to Type B, right? I ask because I rarely see Type B on water heaters. They're almost all single wall.

Originally Posted by John Arnold

This doesn't only apply to Type B, right? I ask because I rarely see Type B on water heaters. They're almost all single wall.

It applies to single vent connectors as well.

You see single wall VENTS all the way? You shouldn't.

Guess I should remove the 'Type B' and just make it 'gas vents' - Done.

NFPA 54: National Fuel Gas Code

See tables.

Calculations and tables differ depending on the circumstances of the installation and the rating of the appliance. Offsets reduce the rating of the vent.

The example given is not all inclusive. The original post is too vague to apply a specific response.

Start with the appliance instructions.

Watson,

What tables?

Oh, right, the table you didn't link to. Your normal style to post an entire code and say 'it is in there, go find it'.

Aw shucks, Watson, you are just so helpful.

By the way, have you gone back and admitted you were wrong on that Type AC stuff in that BX thread? Or, should the question/statement be: 'What, expect Watson to actually publicly admit being wrong? Not on your life.'

Or so your posts have shown us to date.

Start with that one, forget about the others where you were wrong before, make a clean break with that part of your past and become a fruitful contributing member of this board.

I provided link which further provides links to more than one edition of NFPA 54. The chapters and citations (including table numbers) are very different depending on the edition referenced.

Unlike some I do not to violate copyright.

I provided a link for the interested reader to a free resource to review the applicable edition.

The cross-posting, off-topic and ad hominem attacks are boring, tiresome, lazy, akin to stalking & harassment, and representative of a desperately petulant, immature & disturbed party demanding attention.

Originally Posted by H.G. Watson, Sr.

I provided link which further provides links to more than one edition of NFPA 54. The chapters and citations (including table numbers) are very different depending on the edition referenced.

Which is next to useless when posting an answer to a question.

Helpful when one wants to review a code.

Unlike some I do not to violate copyright.

No one else on this board does either.

Name some, heck, just name one, and, of course, provided back up documentation for your accusation.

The cross-posting, off-topic and ad hominem attacks are boring, tiresome, lazy, akin to stalking & harassment, and representative of a desperately petulant, immature & disturbed party demanding attention.

You mean like lying, cheating, changing posts to make you look like you were not wrong, passing off mis-information as though it were good information, and repeatedly failing to acknowledge incorrect and wrong posts, going back and trying to re-word them or massage them into being what they were not, all with the intent of demanding attention to 'Watson is never wrong' way of Watson thinking?

Certainly sounds desperate and immature to me too.

You mean like that? Yes, that certainly describes you to a 'T'.

Cheers.

See, if you were as grown up as you are trying to make us believe, you, as a grown up, would understand that, yes, everyone makes mistakes at some times, and, yes, the best way to get past those mistakes is to admit it openly without trying to obfuscate it into 'well, that other part I said was not completely wrong' instead of just admitting 'Yes, okay, I was wrong'.

Only immature, desperate to impress, tiresome, lazy, incompetent people think they have never done anything wrong. Now whether that is because they simply are too ignorant to know they have done something wrong or incorrect, or whether they are smart enough to realize it and are just too arrogant to admit it, well, there is no way to tell the difference - so you leave that up to us to determine based on your other actions.

Are you too ignorant to know you are wrong? I doubt that, seems like there is a bit of intelligence in there someplace just waiting for an opportunity to get out.

Are you too arrogant to admit you are wrong? That does seem to be the most likely reason. Because, when shown without a doubt that you are wrong, a person who was too ignorant would not think to try to deflect attention to something else they said and try to hide being wrong. Only arrogance does that.

Your call to clear that up.

Originally Posted by Jerry Peck

It applies to single vent connectors as well.

You see single wall VENTS all the way? You shouldn't.

.

No it doesn't.

Yes you can, there are circumstances and locations where this is entirely appropriate and compliant, although Minnesota wouldn't be one of them (too cold in the winter).

Edit to add:

Personally, I don't find assumptive quotations of non-applicable portions of an I-code to a particular jurisdiction helpful. NFPA 54, however is oft referenced in the appliance manufacturer's instructions, therefore it is oft helpful AND applicable.

The location of the original poster is stated as Minnesota. We do not know which county for which there are provisions in the Minnesota rules administration for restrictions by "lines" for things such as snow loads, frost depths, design temps, etc.

Minnesota has its own codes applicable. FYI for your information journey I'll throw in a Link to Minnesota Department of Labor & Industry's Page listing Rule Adoptions and links to those rules (displays as link with *'s):
**

HTH,
H.G.

Originally Posted by Jerry Peck

It applies to single vent connectors as well.

You see single wall VENTS all the way? You shouldn't.

Originally Posted by H.G. Watson, Sr.

No it doesn't.

Documentation back for that statement is needed.

Explain why you say it does not, based on specific code references, not just saying NFPA 54, or some other crap like that. Specifics ... or don't bother not being helpful ("not being helpful" chosen as it specifically represents what you have been doing, er ... "not doing") as your posts are wasted efforts and provide nothing of substance.

Yes you can, there are circumstances and locations where this is entirely appropriate and compliant, although Minnesota wouldn't be one of them (too cold in the winter).

Documentation backup is needed for that statement.

Give an example of a compliant installation which allows single all the way and document with specific code the code (or manufacturer's installation instructions) which allows it - making sure that it fits the content of the thread in which the post was answering.

Not being negative on you, I can see where you *could be a great asset* to this board, if only ... (too many things to list here and this is not the post for it).

Since some practice selective quoting and go ballistic if the make a subsequent post (re-edited previously to explain how link was displaying since it wasn't altogether clear that there was a link imbedded in there, or where it was leading) I'll repost:


Personally, I don't find assumptive quotations of non-applicable portions of an I-code to a particular jurisdiction helpful. NFPA 54, however is oft referenced in the appliance manufacturer's instructions, therefore it is oft helpful AND applicable.

The location of the original poster is stated as Minnesota. We do not know which county for which there are provisions in the Minnesota rules administration for restrictions by "lines" for things such as snow loads, frost depths, design temps, etc.

Minnesota has its own codes applicable. FYI for your information journey I'll throw in a Link to Minnesota Department of Labor & Industry's Page listing Rule Adoptions and links to those rules (displays as link with *'s):
**

HTH,
H.G.

P.S.

It is not my responsibility to "correct" overly broad and erroneous statements of others, especially when those statements are not properly supported.

It is also not my responsiblity to apply a particular code edition reference regarding manufacturer's installation and instructions not knowing the vintage of the appliance in so far as the incorporation of more restrictive requirements from a permissive code section previously cited which was and is not applicable to the jurisdiction location of the original poster.

If a discussion could be had with a particular individual who could control his own commentary and remain ON TOPIC and without off-topic rants, ad hominem attacks, etc. I *might* engage or humor said individual. However, past history and recent evidence on this string by said individual proves otherwise.

As stated previously, the original post is too vague to instill or apply a specific and fully cited response.

As expected, another typical Watson post which offers little, if any, helps of substance.

(sigh)

(Maybe Watson does not have a redeeming value as I have been thinking he had?)

Bob and Jerry,

Thanks for the information-- it came in handy today.