Results 1 to 21 of 21

Thread: Return air

  1. #1
    Join Date
    Mar 2008
    Location
    Park City, Utah
    Posts
    1,530

    Default Return air

    Is this design acceptable? The furnace is housed in the closet a few feet from the return air vent. Does the door have to be sealed? I though the return air had to be 10 feet from the furnace.

    Thanks

    Similar Threads:
    ***IMPORTANT*** You Need To Register To View Images ***IMPORTANT*** You Need To Register To View Images
    Inspection Referral SOC

  2. #2
    Join Date
    Mar 2007
    Location
    Healdsburg, CA
    Posts
    1,741

    Default Re: Return air

    You're right Mathew, refer IRC 1602. What your photo shows is non-code complying.

    Jerry McCarthy
    Building Code/ Construction Consultant

  3. #3
    Join Date
    Aug 2007
    Location
    Memphis TN.
    Posts
    4,311

    Default Re: Return air

    Quote Originally Posted by mathew stouffer View Post
    Is this design acceptable? The furnace is housed in the closet a few feet from the return air vent. Does the door have to be sealed? I though the return air had to be 10 feet from the furnace.

    Thanks
    Quote Originally Posted by Jerry McCarthy View Post
    You're right Mathew, refer IRC 1602. What your photo shows is non-code complying.
    Huh, How ?

    Is there a supply vent , plumbing vent , exhaust fan outlet, I'm not seeing?

    ***IMPORTANT*** You Need To Register To View Images ***IMPORTANT*** You Need To Register To View Images
    Last edited by Billy Stephens; 05-20-2008 at 03:53 PM. Reason: wow to how?
    It Might have Choked Artie But it ain't gone'a choke Stymie! Our Gang " The Pooch " (1932)
    Billy J. Stephens HI Service Memphis TN.

  4. #4
    Join Date
    Mar 2007
    Location
    Philadelphia PA
    Posts
    3,177

    Default Re: Return air

    Quote Originally Posted by Fritz Kelly View Post
    If it is a Cat.IV furnace getting its combustion air from outside, it should be fine.
    Matthew - Can't see from your photos where the furnace is getting combustion air from. As Fritz says, if it's direct vent from outside, that return should be ok.


  5. #5
    Join Date
    Mar 2007
    Location
    Healdsburg, CA
    Posts
    1,741

    Default Re: Return air

    This is not an uncommon problem and does provide a hazard for occupants. Yes, sometimes it's OK if it meets the exceptions to 1602.

    ***IMPORTANT*** You Need To Register To View Images ***IMPORTANT*** You Need To Register To View Images
    Jerry McCarthy
    Building Code/ Construction Consultant

  6. #6
    Join Date
    Mar 2008
    Location
    Park City, Utah
    Posts
    1,530

    Default Re: Return air

    There is a combustion air vent in that little closet. It comes down from the attic. The furnace is a mid efficiency 65,000 btu.

    Mat


  7. #7
    Join Date
    Aug 2007
    Location
    Memphis TN.
    Posts
    4,311

    Default Re: Return air

    Quote Originally Posted by mathew stouffer View Post
    There is a combustion air vent in that little closet. It comes down from the attic. The furnace is a mid efficiency 65,000 btu.

    Mat
    And Why can't the return air vent be at the bottom / sides ?

    You got pictures of the inside setup ?

    It Might have Choked Artie But it ain't gone'a choke Stymie! Our Gang " The Pooch " (1932)
    Billy J. Stephens HI Service Memphis TN.

  8. #8
    Join Date
    Mar 2008
    Location
    Park City, Utah
    Posts
    1,530

    Default Re: Return air

    Billy,
    That is what I am trying to figure out. The code is a little confusing. I thought the return air vent was prohibited from being within ten feet of the furnace.


  9. #9
    Join Date
    Aug 2007
    Location
    Memphis TN.
    Posts
    4,311

    Default Re: Return air

    Matthew,

    The 10 foot rule would be if the furnace and return is in the same space.

    From what you described I would be more concerned about sufficient combustion air supply.

    I see J. L. is replying as well.

    lets read his take.

    It Might have Choked Artie But it ain't gone'a choke Stymie! Our Gang " The Pooch " (1932)
    Billy J. Stephens HI Service Memphis TN.

  10. #10
    Join Date
    Mar 2007
    Location
    Dallas, Texas
    Posts
    4,112

    Default Re: Return air

    IRC 2003
    M1602.1 Return air
    M1602.2 Prohibited sources. Outside or return air for a forced air heating or cooling system shall not be taken from the following locations:
    ...
    5.
    2.3 Return-air inlets shall not be located within 10 feet of any appliance firebox or draft hood in the same room or space.

    While I see no direct requirement for weather stripping, common sense would dictate the need to separate the indoor air from the outdoor air that is inside the furnace closet.

    Jim Luttrall
    www.MrInspector.net
    Dallas, Texas

  11. #11
    Join Date
    Mar 2007
    Location
    Ormond Beach, Florida
    Posts
    25,317

    Default Re: Return air

    Mat,

    Do you have a photo with that door open?

    "How" is that return air inlet connected to the furnace? Is the furnace on a plenum platform, with the return going into the plenum and the furnace setting on the plenum? If so, every one of those installation I've seen leak like a sieve around the furnace/plenum joint.

    Is it a return air duct connected to the furnace in the manner in which ducts are connected, and sealed, to other things, such as with metal collars, sealed, and mechanically attached together?

    Is that return air intake simply cut through the wall?

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

  12. #12
    Join Date
    Mar 2008
    Location
    Park City, Utah
    Posts
    1,530

    Default Re: Return air

    Jerry,
    It is the first and third scenario. The return is cut into the wall and the furnace is sitting a plenum platform made out of OSB i think. I will try to get some pics.


  13. #13
    Join Date
    Mar 2007
    Location
    Ormond Beach, Florida
    Posts
    25,317

    Default Re: Return air

    Mat,

    If that return air plenum is not lined in duct board, taped, sealed, etc., it will be sucking combustion air in all over and around it.

    Plus, that puts the furnace setting on the plenum with little way to seal it up tight, further sucking in combustion air.

    And, unless the opening cut through the stud wall is lined and taped, sealed, etc., it will likely suck air from the wall stud cavities and maybe even up to the attic, and potentially even more combustion air.

    Along with combustion air comes unwanted other contaminates.

    Try this: put a strong scented oil, cinnamon or something, real strong scent, in the closet with the furnace, turn the furnace on, if you smell that in the return air plenum or coming out the supply registers, the return air is sucking that along with combustion air into the return air stream.

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

  14. #14
    Join Date
    Mar 2007
    Location
    Spring Hill (Nashville), TN
    Posts
    5,829

    Default Re: Return air

    Quote Originally Posted by Jerry Peck View Post
    Mat,

    Try this: put a strong scented oil, cinnamon or something, real strong scent, in the closet with the furnace, turn the furnace on, if you smell that in the return air plenum or coming out the supply registers, the return air is sucking that along with combustion air into the return air stream.
    I did that trick with oil of clove in a crawl space last week. I placed four cotton balls soaked in Oil of Clove in a crawl space. We were trying to prove that the return air was sucking air from the crawl space. It took about three minutes before the entire 4,200sf home smelled like an apple pie!

    Word of caution when using any scented oils like this..... Wear disposable gloves and do not touch your eyes or any other sensitive areas of your body!

    Scott Patterson, ACI
    Spring Hill, TN
    www.traceinspections.com

  15. #15
    Join Date
    Mar 2007
    Location
    Healdsburg, CA
    Posts
    1,741

    Default Re: Return air

    The backdrafting, or even better description by EC Jerry's "sucking" of return air into the required combustion air required by a FAU is perhaps one of the most common defects in mechanical systems............ in my opinion.
    Scott's method is a good test and even a couple of moth balls work well. The only problem is catching the little bastantes.

    Jerry McCarthy
    Building Code/ Construction Consultant

  16. #16
    Join Date
    Mar 2008
    Location
    Park City, Utah
    Posts
    1,530

    Default Re: Return air

    Here are some addtional photos of the return air configuration.

    ***IMPORTANT*** You Need To Register To View Images ***IMPORTANT*** You Need To Register To View Images

  17. #17
    Join Date
    Mar 2007
    Location
    Ormond Beach, Florida
    Posts
    25,317

    Default Re: Return air

    Matt,

    Did you remove the return air grille and look in?

    From the photos it has all the defects I expected (regarding this one issue), and, with the door not being weather stripped, no threshold, etc., the combustion air is going to be sucked out around the door and into the return air grille, even is it does not get sucked into the return air plenum.

    I don't see a sediment trap either.

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

  18. #18
    Join Date
    Aug 2007
    Location
    Memphis TN.
    Posts
    4,311

    Default Re: Return air

    Matthew,

    IRC 2003 figure M 1703.3 says you need another combustion air duct within 12 inches from the bottom.

    That said some jurisdictions allow only 1 at the top.

    http://www.muni.org/iceimages/bsd/handoutm03.pdf

    ***IMPORTANT*** You Need To Register To View Images ***IMPORTANT*** You Need To Register To View Images
    It Might have Choked Artie But it ain't gone'a choke Stymie! Our Gang " The Pooch " (1932)
    Billy J. Stephens HI Service Memphis TN.

  19. #19
    Join Date
    Mar 2007
    Location
    Healdsburg, CA
    Posts
    1,741

    Default Re: Return air

    Also, it won't take long before there's a dark strip in the carpeting just below the door to the furnace closet where it will act like a filter to all that sucking air. This phenomenon also occurs at closets containing automatic clothes dryers.

    Jerry McCarthy
    Building Code/ Construction Consultant

  20. #20
    Join Date
    Mar 2008
    Location
    Park City, Utah
    Posts
    1,530

    Default Re: Return air

    Guys,
    Thanks for the imput. All the items you noted were in the report. However, I had that one question about the return air. Thanks for your help.

    Mat


  21. #21
    Richard Stanley's Avatar
    Richard Stanley Guest

    Default Re: Return air

    Word of caution when using any scented oils like this..... ' do not touch any sensitive areas of your body!'

    And you know this because .......??? No pics please!!


Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •