# Furnace Venting

**URL:** <https://forum.nachi.org/t/furnace-venting/18780>\
**Category:** Inspecting HVAC Systems\
**Created:** [July 26, 2007, 2:32am UTC](https://forum.nachi.org/t/furnace-venting/18780 "2007-07-26T02:32:50Z")\
**Posts on this page:** 9\
**Page:** 1

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**Author:** ![bpaull](https://avatars.discourse-cdn.com/v4/letter/b/58956e/32.png) [@bpaull](https://forum.nachi.org/u/bpaull)\
**Post date:** [July 26, 2007, 2:32am UTC](https://forum.nachi.org/t/furnace-venting/18780/1 "2007-07-26T02:32:50Z")

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This is the first time I have seen this. Newer Trane furnace vents up through the roof and in the attic area, they merge together to a single vent. Is this a proper installation method?

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**Author:** ![sparksnmore](https://avatars.discourse-cdn.com/v4/letter/s/c68b51/32.png) [@sparksnmore](https://forum.nachi.org/u/sparksnmore)\
**Post date:** [July 26, 2007, 2:54am UTC](https://forum.nachi.org/t/furnace-venting/18780/2 "2007-07-26T02:54:59Z")

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I would need to see the manufacture’s installation instructions myself.  
What is the second pipe ?

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**Author:** ![bpaull](https://avatars.discourse-cdn.com/v4/letter/b/58956e/32.png) [@bpaull](https://forum.nachi.org/u/bpaull)\
**Post date:** [July 26, 2007, 3:04am UTC](https://forum.nachi.org/t/furnace-venting/18780/3 "2007-07-26T03:04:39Z")

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Sorry, I should have noted that. One is the intake and the other is the exhaust. The furnace is less than 5 years old, but the instructions were not available.

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**Author:** ![sparksnmore](https://avatars.discourse-cdn.com/v4/letter/s/c68b51/32.png) [@sparksnmore](https://forum.nachi.org/u/sparksnmore)\
**Post date:** [July 26, 2007, 3:16am UTC](https://forum.nachi.org/t/furnace-venting/18780/4 "2007-07-26T03:16:30Z")

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I’ve never seen or heard of the intake and exhaust being connected together, but then I’ve never installed Trane equipment.  
I don’t see how that could possibly work.

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**Author:** ![cbuell](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/cbuell/32/1773_2.png) [@cbuell](https://forum.nachi.org/u/cbuell)\
**Post date:** [July 26, 2007, 4:34am UTC](https://forum.nachi.org/t/furnace-venting/18780/5 "2007-07-26T04:34:32Z")

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This is a very common installation. They don’t actually vent together. One pipe just runs inside the other so that you only have to put one hole through the roof.

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**Author:** ![lkage](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/lkage/32/347658_2.png) [@lkage](https://forum.nachi.org/u/lkage)\
**Post date:** [July 26, 2007, 10:57am UTC](https://forum.nachi.org/t/furnace-venting/18780/6 "2007-07-26T10:57:43Z")

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> [@cbuell](#):
>
> This is a very common installation. They don’t actually vent together. One pipe just runs inside the other so that you only have to put one hole through the roof.

Exactly…quite common installation.

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**Author:** ![sparksnmore](https://avatars.discourse-cdn.com/v4/letter/s/c68b51/32.png) [@sparksnmore](https://forum.nachi.org/u/sparksnmore)\
**Post date:** [July 26, 2007, 1:03pm UTC](https://forum.nachi.org/t/furnace-venting/18780/7 "2007-07-26T13:03:17Z")

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Ah ha, that makes sense now then.  
It must be a special wye fitting.

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**Author:** ![mlarson](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/mlarson/32/89225_2.png) [@mlarson](https://forum.nachi.org/u/mlarson)\
**Post date:** [July 26, 2007, 1:21pm UTC](https://forum.nachi.org/t/furnace-venting/18780/8 "2007-07-26T13:21:40Z")

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Picture is upside down.

\*\*Vent Termination Kit \*\*

```
          Concentric Vent Termination Kit, 3 Inches     
                                                                     Grainger Item # 6MC43 Price (ea.) **$67.50**                                                                                                 
                                         Brand DAYTON Mfr. Model # 6MC43 Ship Qty. [http://images.grainger.com/images/icon_help.gif](http://www.grainger.com/Grainger/items/6MC43#) 1 Sell Qty. (Will-Call) [http://images.grainger.com/images/icon_help.gif](http://www.grainger.com/Grainger/items/6MC43#) 1 Ship Weight (lbs.) 5.0 Usually Ships** [http://images.grainger.com/images/icon_help.gif](http://www.grainger.com/Grainger/items/6MC43#) [Today](http://www.grainger.com/Grainger/items/6MC43#) Catalog Page No. [3219

```

[http://images.grainger.com/images/mini\_catalog.gif](http://images.grainger.com/images/mini_catalog.gif)]([http://www.grainger.com/Grainger/items/6MC43#](http://www.grainger.com/Grainger/items/6MC43#))

[http://images.grainger.com/images/products/6MC42.JPG](http://images.grainger.com/images/products/6MC42.JPG)

```
             [http://images.grainger.com/images/icon_enlargeimage.gif

```

Enlarge Image]([http://www.grainger.com/Grainger/items/6MC43#](http://www.grainger.com/Grainger/items/6MC43#))

[Installation sheet](http://johnsonsupply.com/york2001/PUB/65075/OUT/N2_4u799.pdf)

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**Author:** ![bpaull](https://avatars.discourse-cdn.com/v4/letter/b/58956e/32.png) [@bpaull](https://forum.nachi.org/u/bpaull)\
**Post date:** [July 26, 2007, 3:08pm UTC](https://forum.nachi.org/t/furnace-venting/18780/9 "2007-07-26T15:08:42Z")

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Thanks everyone…It was a good day, I learned something.