Single wall exhaust vent in garage

[Ponyboy]

Having a little dipute with a furnace guy. I called out the single wall flue connector in the garage for the furnace and water heater. The garage is barely attached to the house, is old and uninsulated. I know this is a cold area and should be B-vent, but code check does not specifically state garages only cold areas. Am I right in calling for a B-vent at this location?

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[hausdok]

Hi Brad,

You were up until the 2006 version of the code when that requirement was removed.

I'm not sure why they removed it. Given the amount of damage I constantly find caused around here by use of single-walled vents in cold areas, you'd think the HVAC code gurus would have known better.

I usually point out to the client that until the last go-round a double-walled vent was mandated, explain why, and recommend that, despite the new rule, they consider having one installed at their own expense or at least formally ask the HVAC guy to replace it so that they'll have it on record if something goes amiss later on.

So far, I've seen two 1-year old furnaces with single-walled vents where there has been a lot of excess condensation taking place. I think this is one of those things that they'll eventually have to do an about-face on.

ONE TEAM - ONE FIGHT!!!

Mike

[Bill Kibbel]

From the 2006 IRC, if applicable in your area:

G2427.10.2.2 (503.10.2.2) Vent connectors located in unconditioned areas. Where the vent connector used for an appliance having a draft hood or a Category I appliance is located in or passes through attics, crawlspaces or other unconditioned spaces, that portion of the vent connector shall be listed Type B, Type L or listed vent material having equivalent insulation properties.

Exception: Single-wall metal pipe located within the exterior walls of the building in areas having a local 99-percent winter design temperature of 5°F (-15°C) or higher shall be permitted to be used in unconditioned spaces other than attics and crawl spaces.

[Tom Corrigan]

Brad,

You may want to review the furnace manufacturers installation instructions. Your picture shows a combustion assist fan type furnace. Every one I've seen calls for b-vent starting at the furnace.

Tom Corrigan

[Ponyboy]

Thanks guys, I called for installing B-vent from the furnace to the existing B-vent. The furnace is about ten years old so it should be B-vent. Bill, thanks for the expanded code wording. Code check had the same information but in their condensed fashion.

Thanks Brad

[waynesoper]

does that furnace burner meet the 16"rule?

[Tom Raymond]

OK, dumb question but here goes... wouldn't it make sense to inform your client that by insulating the space they could improve the efficiency of the equipment? This type of improvement qualifies for a 30% tax credit up to $1500, would correct the vent pipe deficiency, reduce their anual operating costs and increase the service life of the equipment. Makes a hell of alot more sense to me.

Tom

[hausdok]

Hmm,

Spend $2000 to get a $1500 credit for a garage when all it takes is changing out $40 worth of pipe?

OT - OF!!!

M.

[hmiller]

I am not sure what the point in calling out what appears to be a sound looking single wall vent is. Our job is not to interpret codes, like municipal code officials, and then try to apply them to 10 year old homes, ....or new homes for that matter. Our job is to report the "condition" of what is present. If it is "defective" then call it like it is. But calling to replace a perfectly sound single wall vent, because it may or may not meet some code at some point in time is over-stepping.

[Darren]

Telling your client to change something that's wrong will prevent this from happening.

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[waynesoper]

Is that furnace sitting on the floor of the garage?

[RobC]

Are you allowed to use aluminum supply ducting for C' vent?

I'd also like to see a base T'

[RobC]

I am not sure what the point in calling out what appears to be a sound looking single wall vent is. Our job is not to interpret codes, like municipal code officials, and then try to apply them to 10 year old homes, ....or new homes for that matter. Our job is to report the "condition" of what is present. If it is "defective" then call it like it is. But calling to replace a perfectly sound single wall vent, because it may or may not meet some code at some point in time is over-stepping.

Fantastic!