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  1. #1
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    Mar 2011
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    Default Venting Question

    Hi All,

    Saw this duct pipe opened on the bottom and not sure were it terminates.This is a condo with a 80,000 BTU furnace in a closet with a by fold door. I believe the intent of this duct is to bring fresh air for the furnace. But not sure. I wrote it up as needs " further evaluation" by an Hvac contractor. Put if anyone has an opinion it would be most welcome.

    Happy Holidays to all my colleagues

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    Fidel F. Gonzales
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  2. #2
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    Default Re: Venting Question

    Quote Originally Posted by fidel gonzales View Post
    Hi All,

    Saw this duct pipe opened on the bottom and not sure were it terminates.This is a condo with a 80,000 BTU furnace in a closet with a by fold door. I believe the intent of this duct is to bring fresh air for the furnace. But not sure. I wrote it up as needs " further evaluation" by an Hvac contractor. Put if anyone has an opinion it would be most welcome.

    Happy Holidays to all my colleagues
    Looks like a combustion air supply for the furnace. Was there proper combustion air for the furnace in the room?

    Usually you will see two pipes, one high and one lower like the one in the picture. They are commonly called "high low" combustion air vents.

    Not sure why you would call it out as needing further evaluation unless the room did not have enough combustion air.

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

  3. #3
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    Default Re: Venting Question

    Quote Originally Posted by Scott Patterson View Post
    Looks like a combustion air supply for the furnace. Was there proper combustion air for the furnace in the room?

    Usually you will see two pipes, one high and one lower like the one in the picture. They are commonly called "high low" combustion air vents.

    Not sure why you would call it out as needing further evaluation unless the room did not have enough combustion air.

    Thanks Scott, I knew I could count on you to give the correct answer. I'll amendmy report before it goes out. I just never saw this type of connection.Although I did thought it was for airfor the furnace. Anyway, thanks a million for your help.


    Fidel F. Gonzales
    RELIANT INSPECTION SERVICE
    http://www.reliantinspectionservice.com

  4. #4
    Join Date
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    Default Re: Venting Question

    Quote Originally Posted by Scott Paterson
    Not sure why you would call it out as needing further evaluation unless the room did not have enough combustion air.
    Scott,

    That is an interesting comment. I didn't expect that one from you.

    Certainly, One wouldn't be able to determne if there was "enough" combution air, unless a unit input capacity and volummetric calculation and/or an air flow evaluation out of that duct was performed.

    Do YOU perform these calculations AND then put in writting that it is SAFE and OK to use like it is? If the answer is yes, my next question would be are you licensed to determine if the room "did not have enough combustion air"?

    Ken Amelin
    Cape Cod's Best Inspection Services
    www.midcapehomeinspection.com

  5. #5
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    Default Re: Venting Question

    Fidel - You're ok to let that slide. Scott is correct about having two ducts - one high and one low. If the door is fully louvered then the duct can be sealed closed if desired.

    Eric Barker, ACI
    Lake Barrington, IL

  6. #6
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    Default Re: Venting Question

    Quote Originally Posted by Ken Amelin View Post
    Scott,

    That is an interesting comment. I didn't expect that one from you.

    Certainly, One wouldn't be able to determne if there was "enough" combution air, unless a unit input capacity and volummetric calculation and/or an air flow evaluation out of that duct was performed.

    Do YOU perform these calculations AND then put in writting that it is SAFE and OK to use like it is? If the answer is yes, my next question would be are you licensed to determine if the room "did not have enough combustion air"?
    It is not difficult to calculate room size and the amount of combustion/makeup air that a gas appliance needs based on its btu's. I think even Code Check has a simple chart you can use to calculate a rooms cubic footage and then how much cubic footage is required to satisfy the combustion air requirements for the amount of btu's.

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

  7. #7
    Ted Menelly's Avatar
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    Default Re: Venting Question

    Quote Originally Posted by Ken Amelin View Post
    Scott,

    That is an interesting comment. I didn't expect that one from you.

    Certainly, One wouldn't be able to determne if there was "enough" combution air, unless a unit input capacity and volummetric calculation and/or an air flow evaluation out of that duct was performed.

    Do YOU perform these calculations AND then put in writting that it is SAFE and OK to use like it is? If the answer is yes, my next question would be are you licensed to determine if the room "did not have enough combustion air"?
    That goes a bit deep Ken.

    If one has looked at enough as in hundreds maybe thousands for a lot of us our best guesstimate is almost spot on all the time without having to call in an outside expert or do elaborate testing.

    I know I know....best guesstimate???? I can hear the come back now before I finish typing this. But, as Scott said the simple calcs will get one pretty darn close in almost all cases.

    Now if anything looks rather questionable then we turn it over for repair by the HVAC folks.

    I hope you are not saying that every time you see a heating unit in a closet and you see combustion air and sealed closet as in weather stripped you don't calculate in your head or you do or you do more elaborate testing or what exactly? You always call for an HVAC company to come out to figure it out???? Not sure what you are saying.

    What do you do

    Just curious.


  8. #8
    Join Date
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    Default Re: Venting Question

    Yes, looks like typical combustion air pipe. They tried, that's more than most places.
    Might want to tell the client to budget for a new furnace over time.

    www.aic-chicago.com
    773/844-4AIC
    "The Code is not a ceiling to reach but a floor to work up from"

  9. #9
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    Default Re: Venting Question


    Quote Originally Posted by Ted Menelly
    I hope you are not saying that every time you see aheating unit in a closet and you see combustion air and sealed closet as inweather stripped you don't calculate in your head or you do or you do moreelaborate testing or what exactly? You always call for an HVAC company to comeout to figure it out???? Not sure what you are saying.
    Quote Originally Posted by Ted Menelly

    What do you do

    Just curious.


    I never do any calculations (it's not my job OR within the authority of mylicense) I make a judgment based on my observations and report one ofthe following:

    1. Do nothing if it looks like it is in an open basementor attic space.

    2. Recommend review of ventilation with regular serviceand maintenance.

    3. Recommend repair NOW, prior to purchase.

    In this case, the picture provided would indicate that the duct was for theintroduction of outside air. I would state my observation and my recommendation(in this case) would be further evaluation advised at next service and maintenance.

    (The correct way would be to determine if the size of the duct was OK basedon free area and equivalent length of duct or to fire up the unit and take adraft measurement at the hood inlet Neither of which I am an expert at.)


    Ken Amelin
    Cape Cod's Best Inspection Services
    www.midcapehomeinspection.com

  10. #10
    Ted Menelly's Avatar
    Ted Menelly Guest

    Default Re: Venting Question

    Quote Originally Posted by Ken Amelin View Post


    I never do any calculations (it's not my job OR within the authority of mylicense) I make a judgment based on my observations and report one ofthe following:

    1. Do nothing if it looks like it is in an open basementor attic space.

    2. Recommend review of ventilation with regular serviceand maintenance.

    3. Recommend repair NOW, prior to purchase.

    In this case, the picture provided would indicate that the duct was for the introduction of outside air. I would state my observation and my recommendation(in this case) would be further evaluation advised at next service and maintenance.

    (The correct way would be to determine if the size of the duct was OK basedon free area and equivalent length of duct or to fire up the unit and take adraft measurement at the hood inlet Neither of which I am an expert at.)
    So in the case of this picture (which is not telling me much of the total enclosure at all) you would flat out recommend any closet or enclosed space that a heating unit is in that has combustion air fed into it

    2. Recommend review of ventilation with regular service and maintenance.

    3. Recommend repair NOW, prior to purchase.

    Considering that today I inspect an extreme amount of newer homes with the units in the attic I would never make that call

    Now as far as the rest of the homes I inspect almost every single one of them has a heating unit in the closet somewhere in the home.

    What you are saying is that every single one of them you would recommend further review to all that has (and of course those that don't at all) combustion air fed into the enclosure.

    I guess this would be the hundreds of water heaters I see every year that are in garage closets or in the home in closets that are gas fed that have combustion air allowances into those enclosures.

    That sounds like every older home in my area needs review by an HVAC contractor.. I guess that includes the tremendous amount of new or newer homes that I find water heaters in garage closets as well. Call the Plumber??

    Just sounds a bit to much of deferral to me and quite unnecessary. IMHO

    As a matter of fact I find a lot of new homes that have sealed closets and combustion air fed into that closet whether it be HVAC or water heaters.


  11. #11
    Join Date
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    Default Re: Venting Question

    The "room" containing the "furnace" was described as a "closet" with a bi-fold door. The edge of the door panel is pictured - it is NOT a louvered door. The OP described ONLY a "low" open this is for combustion AND make-up air. That in and of itself requires review - as the OP makes no reference of a "high" source of air. Likely said "closet" originally had a louvered door and was replaced the bi-fold door. Correction is necessary 80Kbtu FA furnace requires make-up air, dillution air AND combustion air, a non-louvered bi-fold door to a "closet" is an enclosed space. Calculation of volume is H x L x W MINUS contents.


  12. #12
    Ted Menelly's Avatar
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    Default Re: Venting Question

    Quote Originally Posted by H.G. Watson, Sr. View Post
    The "room" containing the "furnace" was described as a "closet" with a bi-fold door. The edge of the door panel is pictured - it is NOT a louvered door. The OP described ONLY a "low" open this is for combustion AND make-up air. That in and of itself requires review - as the OP makes no reference of a "high" source of air. Likely said "closet" originally had a louvered door and was replaced the bi-fold door. Correction is necessary 80Kbtu FA furnace requires make-up air, dillution air AND combustion air, a non-louvered bi-fold door to a "closet" is an enclosed space. Calculation of volume is H x L x W MINUS contents.
    On a technicality I stand corrected. I should have not regarded the picture at all. My response was to all closets with combustion air that have a heater or water heater in it. As in if one sees a unit with combustion air delivered. I see no reason at all to write them all up. There are extremely simple methods of determining combustion air when inspecting and getting it so close that the difference is really no difference.

    Now I will probably be corrected again but the facts are most if not all home inspectors should do at least some simple calcs even if it is just measuring the size of the unit and the size of high and low air introduction.

    I for one call it make up for combustion air and ventilation at the top. Call it what ever you wish it still comes out the same. I can look at about any enclosure and tell if it is just about spot on or not without measuring down to the fractions. After many many years (decades in many inspectors cases) One should be able to tell if it is that out of whack for further evaluation by an HVAC contractor. Even then the experienced HVAC man is just going to come, look, determine and atta here!

    Yeah yeah, a little more than that and maybe a couple quick measurements. I am quite sure you know what I meant. That is without getting to technical. If one does not know then one must go back to the basics to figure it out. This man found out what the pipe is for and now will (I am quite sure) delve a bit deeper into being able to figure it out. Or ask more questions until he does.

    So, lets go a bit deeper here.

    I am not a licensed roofer (don't have to be in this state anyway). a licensed electrician, a licensed HVAC man, a licensed plumber.........so what you folks are saying is, exactly what??????

    Call for further evaluation on every item involving any different trade (that would be the entire home by the way) Never open an electric panel, look at overhead service wires, never look at any plumbing. Not an engineer so never look at a foundation, pre pour, grading and drainage.......................................... .............................................

    By the way I do use the term further evaluation is needed......when I do find something wrong..............Sorry Jerry! Don't yell at me!

    Well. I think I made my point

    Atta here!


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