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Thread: Return Air

  1. #1
    David Banks's Avatar
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    Default Return Air

    Condo. Return air. Within 10 feet from appliance vent outlet but from different room. I see this in condos.
    Exception seems to say this setup is OK.
    IRC M1602.2 Exception to 10 ft. rule. (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.

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  2. #2
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    Default Re: Return Air

    It's ok. As you found, it's not in the same room or space.

    Eric Barker, ACI
    Lake Barrington, IL

  3. #3
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    Default Re: Return Air

    That's not what the code says or how you read it.

    - M1602.2 Prohibited sources. Outdoor and return air for a forced-air heating or cooling system shall not be taken from the following locations:
    - - 1. Closer than 10 feet (3048 mm) to an appliance vent outlet, a vent opening from a plumbing drainage system or the discharge outlet of an exhaust fan, unless the outlet is 3 feet (914 mm) above the outside air inlet.
    - - 2. Where flammable vapors are present; or where located less than 10 feet (3048 mm) above the surface of any abutting public way or driveway; or where located at grade level by a sidewalk, street, alley or driveway.
    - - 3. A room or space, the volume of which is less than 25 percent of the entire volume served by such system. Where connected by a permanent opening having an area sized in accordance with ACCA Manual D, adjoining rooms or spaces shall be considered as a single room or space for the purpose of determining the volume of such rooms or spaces.
    - - - Exception:
    The minimum volume requirement shall not apply where the amount of return air taken from a room or space is less than or equal to the amount of supply air delivered to such room or space.
    - - 4. A closet, bathroom, toilet room, kitchen, garage, mechanical room, furnace room or other dwelling unit.
    - - 5. A room or space containing a fuel-burning appliance where such room or space serves as the sole source of return air.

    - - - Exceptions:
    - - - - 1. The fuel-burning appliance is a direct-vent appliance or an appliance not requiring a vent in accordance with Section M1801.1 or Chapter 24.
    - - - - 2. The room or space complies with the following requirements:
    - - - - - 2.1. The return air shall be taken from a room or space having a volume exceeding 1 cubic foot for each 10 Btu/h (9.6 L/W) of combined input rating of all fuel-burning appliances therein.
    - - - - - 2.2. The volume of supply air discharged back into the same space shall be approximately equal to the volume of return air taken from the space.
    - - - - - 2.3. Return-air inlets shall not be located within 10 feet (3048 mm) of any appliance firebox or draft hood in the same room or space.
    - - - - 3. Rooms or spaces containing solid-fuel burning appliances, provided that return-air inlets are located not less than 10 feet (3048 mm) from the firebox of such appliances.

    That says that return air 'must not' be taken from the following locations.

    Then you apply 1., 2., 3., 4., and 5. independently to the "must not". You do not take exceptions from one and apply to the other.

    So ...

    1. says closer than 10 feet to an appliance vent outlet ...

    2. says where flammable vapors are present ...

    3. says from a room or space where the volume is less than ...

    4. says from a closet, bathroom, ...

    and 5. says from a room containing a fuel-burning appliance where ...

    1. does not say anything about being in the same room or not, it simply says that return air "shall not be taken from the following locations:
    - - 1. Closer than 10 feet (3048 mm) to an appliance vent outlet, a vent opening from a plumbing drainage system or the discharge outlet of an exhaust fan, unless the outlet is 3 feet (914 mm) above the outside air inlet."

    You apply the rest in the same manner:
    "shall not be taken from the following locations:
    - - (insert numbered 'shall not be taken from here')



    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
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  4. #4
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    Default Re: Return Air

    These are from my inspection yesterday. Pretty cut and dry.

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    Wink Re: Return Air

    Did you add the smoke to that picture for effect?

    Mike Schulz License 393
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  6. #6
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    Default Re: Return Air

    I thought it was a ghostly orb............or a fingerprint on my camera lense.


  7. #7
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    Default Re: Return Air

    Nick: You are right - it's cut and dry - it's ok. In Jerry's post above, read exception 2.3. The open return cannot be within 10 feet when in the same room or space. The vents in both Dave's and your pictures are not within the same room or space. Whether you agree with it or not, the louvered doors create a separation of space. The return locations are acceptable in both pictures.

    Eric Barker, ACI
    Lake Barrington, IL

  8. #8
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    Default Re: Return Air

    Quote Originally Posted by Eric Barker View Post
    In Jerry's post above, read exception 2.3. The open return cannot be within 10 feet when in the same room or space.
    (sigh)

    No, it does not.


    - M1602.2 Prohibited sources. Outdoor and return air for a forced-air heating or cooling system shall not be taken from the following locations:
    - - 3. A room or space, the volume of which is less than 25 percent of the entire volume served by such system. Where connected by a permanent opening having an area sized in accordance with ACCA Manual D, adjoining rooms or spaces shall be considered as a single room or space for the purpose of determining the volume of such rooms or spaces.


    Please, anyone, show me where it says " 10 feet " in the above 2.3.


    Jerry Peck, Construction / Litigation Consultant
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  9. #9
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    Default Re: Return Air

    Jerry:


    EXCEPTION 2.3

    It's right there in your post. You are reading only M1602.2
    Read further and you will see exceptions listed.
    Under the second "exceptions" heading you will find 2.3

    Eric Barker, ACI
    Lake Barrington, IL

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  11. #11
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    Default Re: Return Air

    Thanks, Michael. Info shared that also has pictures is always helpful when I'm trying to explain something to Clients (or better understand it myself).

    The only reason some people get lost in thought is because it's unfamiliar territory.
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  12. #12
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    Default Re: Return Air

    I'm not citing code in my inspections Eric, I'm citing safety. And to me, neither of the configurations in my pics is what I would consider safe. I'd call it out every time regardless of what the code says.


  13. #13
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    Default Re: Return Air

    Eric,

    No, that's:

    M1602.2 .5. Exceptions: 2.3. Return-air inlets shall not be located within 10 feet (3048 mm) of any appliance firebox or draft hood in the same room or space.

    Saying that is 'exception 2.3' means nothing.

    This is really what you are referring to:

    M1602.2 Prohibited sources. Outdoor and return air for a forced-air heating or cooling system shall not be taken from the following locations:
    - - 5. A room or space containing a fuel-burning appliance where such room or space serves as the sole source of return air.
    - - - Exceptions:
    - - - - 2. The room or space complies with the following requirements:
    - - - - - 2.1. The return air shall be taken from a room or space having a volume exceeding 1 cubic foot for each 10 Btu/h (9.6 L/W) of combined input rating of all fuel-burning appliances therein.
    - - - - - 2.2. The volume of supply air discharged back into the same space shall be approximately equal to the volume of return air taken from the space.
    - - - - - 2.3. Return-air inlets shall not be located within 10 feet (3048 mm) of any appliance firebox or draft hood in the same room or space.

    Now let's read that.

    M1602.2 'return air ... shall not be taken from'
    M1602.2.5 'A room or space containing a fuel-burning appliance where such room or space serves as the sole source of return air.' (Jerry's note: Stop right there IF that is a room which DOES NOT contain a fuel-burning appliance AND the room serves as the SOLE source of return air. IF those two things do not apply, then this does not apply, no need to continue on.)
    M1602.2.5 Exception 2. '2. The room or space complies with the following requirements:' (Jerry's note: The room must comply with each of the following for Exception 2. to be applicable.)
    - 2.1. The return air shall be taken from a room or space having a volume exceeding 1 cubic foot for each 10 Btu/h (9.6 L/W) of combined input rating of all fuel-burning appliances therein. (Jerry's note: Did you measure this? Did this apply? If not, no need to continue.)
    - 2.2. The volume of supply air discharged back into the same space shall be approximately equal to the volume of return air taken from the space.(Jerry's note: Did you check for this? Did this apply? If not, no need to continue.)
    - 2.3. Return-air inlets shall not be located within 10 feet (3048 mm) of any appliance firebox or draft hood in the same room or space.(Jerry's note: The 10 feet only comes into play *IF* 2.1 AND 2.2 have already been met, otherwise *The room or space DOES NOT comply with the following requirements*.)

    You cannot simply take Exceptions out of wherever you want and refer to them by a partial number, i.e., saying "Exception 2.3" is meaningless without first stating what it is under (see above regarding this), then, you cannot take one-part-of an exception and refer to it or apply it without first reading and applying the condition for that exception.

    In other words, M1602.2 .5. Exception: 2.3. ONLY applies IF M1602.2 .5. Exception: 2 applies. So you have to go back to Exception 2 and read it, then read 2.1, 2.2, and finally 2.3

    Thus, and finally, that 10 foot separation only applies if the other conditions apply, and then it simply says that, if the other conditions in Exception 2 apply, then the return air must also be 10 feet from the fuel burning appliance. However, if the rest of the conditions in Exception 2 are not meet, then you must fall back to 5., which is where return air cannot be taken.

    That is read like telling your kid 'You must not do A, but, if you do this other thing B, I will allow you to do A if B, B1, B2 and B3 are done.'

    You cannot go out and play ball with the other kids (A) ... unless your room is clean (B) ... which includes making your bed (B1) ... hanging up your clothes (B2) ... and cleaning the pizza from last night out of your carpet (B3).

    How bad do you want to go out and play with your friends?

    What friends? I'm staying in and playing video games. Guess who won that one?


    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
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  14. #14
    Richard Rushing's Avatar
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    Default Re: Return Air

    I think we can try and decypher the intricies of the IRC, IMC, IBC and the KMA... but what we have to do as someone who is suppose to have a clue is determine if our experience, training and sense of what is right/wrong is just taking us wandering around, aim-lessly writing stuff up because we can... or, do we really know if a condition is present--will it have a negative effect monetarily, if it will have a negative effect on the dwelling or be a safety concern to the buyers or occupants?

    If I/you can answer that question with a yes... you don't need CODE. The simple fact that it will cost the occupants money, have a negative effect on the dwelling or become a health/safety concern is paramount in why/how we conduct our business.

    Irrespective of how you intreprete the code... that set up and the set-ups in Nick's pictures has a negative effect on the livable space.

    I'd write that sucker up every time.

    Rich


  15. #15
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    Default Re: Return Air

    Michael:

    Thanks for posting the People Energy info. I haven't been able to find my copy. Did you attend the seminars - great stuff. Those guys are extremely safety conscious. The diagram on page 16 is what I was looking for.

    If the gas companies, as anal as they are, allow such a condition then a H.I.'s saying that it's wrong or unsafe is really nothing more than an opinion and cannot be backed up. I continue to disagree with Jerry's assessment.

    Eric Barker, ACI
    Lake Barrington, IL

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    Default Re: Return Air

    "Did you attend the seminars"

    Yes. Very worthwhile. The Chicago NACHI chapter has the same deal with People's Energy going again this year, 12 hrs of state CE , BTW.


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    Default Re: Return Air

    Hate to bring up a thread from the dead but I felt I might have something to add that would be beneficial.

    If the return in question is communicating with the same space as a draft hood equipped appliance testing the draft of the appliance with a draft gauge while the blower is off then running is the only way to verify if it is affecting the appliances ability to establish draft & maintain it.

    If the appliances draft drops when the blower is kicked on it is interfering with that appliances ability to draft & should be addressed immediately.

    You can go into a lot more detail on this but this is just an observation.

    Measured Performance more than just a buzzword

  18. #18
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    Default Re: Return Air

    David,

    That would be a start. Other factors can contribute. A filthy system, filter, blower and evaporator coil as well as some registers being closed, will not draw as much air as a clean system. You would also want to consider the ways a home can be depressurized - exhaust fans and fireplaces.

    Certainly the method you present is valid but I wouldn't let it be the last word.

    Eric Barker, ACI
    Lake Barrington, IL

  19. #19
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    Default Re: Return Air

    Eric,

    I have found draft interference testing to rule out nearly everything mechanically related that will effect an appliances ability to draft.

    Two things it cannot predict are wind & stack effect in colder weather.

    I would never rely on draft testing alone to declare an appliance safe, full combustion testing over possibly multiple cycles would be needed in addition for that.

    Measured Performance more than just a buzzword

  20. #20
    Mr Bill's Avatar
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    Default Re: Return Air

    Quote Originally Posted by Richard Rushing View Post
    I think we can try and decypher the intricies of the IRC, IMC, IBC and the KMA... but what we have to do as someone who is suppose to have a clue is determine if our experience, training and sense of what is right/wrong is just taking us wandering around, aim-lessly writing stuff up because we can... or, do we really know if a condition is present--will it have a negative effect monetarily, if it will have a negative effect on the dwelling or be a safety concern to the buyers or occupants?

    If I/you can answer that question with a yes... you don't need CODE. The simple fact that it will cost the occupants money, have a negative effect on the dwelling or become a health/safety concern is paramount in why/how we conduct our business.

    Irrespective of how you intreprete the code... that set up and the set-ups in Nick's pictures has a negative effect on the livable space.

    I'd write that sucker up every time.

    Rich


    Rich, that is an excellent attitude and post I wish "every" HI would develop that attitude life would be good for us
    A/C guys.I mean I know you guys could write up a 100 page report in just about any home if time allowed and you were just bored, but what you just wrote in your post is the way I would look at it if I were a HI.
    I mean sometimes we have to just face it even in my business it's been that way for 15/20 years and has been fine and now we want to condemn something that will require a total rebuild of the home, real safety issues yes write them down no doubt.


  21. #21
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    Default Re: Return Air

    Mr. Bill,
    You're new to this site and you're an alien! What part of "natural enemies" don't you understand? If you continue to contribute using common sense and respect for other people, and if you to continue to actually read the posts of others before giving your opinion, I'll have to ask you to leave.

    PS Let me guess, you're probably also a proponent of licensing.

    The only reason some people get lost in thought is because it's unfamiliar territory.
    - Paul Fix

  22. #22
    Mike Huppi's Avatar
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    Question Re: Return Air

    Ok I am still a little confused which sometimes can be easy.

    The home I just did had a lot of issues but the question I have is the furnace was in a closet, it only had one opening and that was right on the floor in the wall for combustion air, I know that it needs another one up on the top. The cold air return was only 16" form the combustion air inlet. Is it ok or not. It was in a basement hallway that was open to the stairway that is open to the second floor.


  23. #23
    Richard Rushing's Avatar
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    Default Re: Return Air

    Quote Originally Posted by Mike Huppi View Post
    Ok I am still a little confused which sometimes can be easy.

    The home I just did had a lot of issues but the question I have is the furnace was in a closet, it only had one opening and that was right on the floor in the wall for combustion air, I know that it needs another one up on the top. The cold air return was only 16" form the combustion air inlet. Is it ok or not. It was in a basement hallway that was open to the stairway that is open to the second floor.
    Herein (the bold highlighted section above) lies the rub... It it now a confined space? Maybe not....

    The requirements of needing two opens; one top and one bottom (within the top and bottom 12 inches) with 100 square inches (minimum) each-- with requirements of one square inch per 1,000/btu input and not less than 3 square inches in it's least dimension are the bare-butt minimum requirements. Thus the above minimum of 200 square inches is adequate for up to 100,000 btu's.

    Clear as mud... Now, here is the kicker (as highlighted above);
    1. The basement hallway was open to the stairway
    2. The stairway was open to the second floor
    Now... where is the confined space?


    By the way Bill (in Houston)-- thanks for the afformation... The reality is, most of the folks on this board conduct their business in the same respect and are, for the most part, people that I would want to work on my behalf or for my family. Since the codes do not always allow for common sense, at some point, we have to NOT step in that big, thick, steaming pile of poo when we see it. Walking around it is an option, but it's best served if we let someone know so they don't step in it too.

    Richard

    Last edited by Richard Rushing; 05-11-2007 at 01:06 PM. Reason: Added "thanks"

  24. #24
    Mike Huppi's Avatar
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    Default Re: Return Air

    Ok but the return air duct or opening to the furnace was only about 16" away from the combustion air opening to the furnace so would it not be possible for the return air opening to suck the air from the combustible air opening and bringing that air into the heating duct system? Or flue gasses being brought into the home instead of up the flue pipe.


  25. #25
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    Default Re: Return Air

    Quote Originally Posted by Mike Huppi View Post
    Ok but the return air duct or opening to the furnace was only about 16" away from the combustion air opening to the furnace so would it not be possible for the return air opening to suck the air from the combustible air opening and bringing that air into the heating duct system? Or flue gasses being brought into the home instead of up the flue pipe.

    That scenario is very likely & happens daily.

    Measured Performance more than just a buzzword

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