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  1. #1
    Join Date
    Jan 2011
    Posts
    57

    Some General HVAC Question

    Sorry for the lengthy post..

    I read through the rules of the site about no DIY stuff and I think I udnerstand it. So let me be clear from the get go, I am doing a full DIY duct install in my house. However, I am not coming here for step by step tutorials on how to do it.

    I am a fairly handy person and feel very comfortable doing it, but because I am not in the profession I do have a few things I am unsure about and am hoping someone here would be able to help.

    If this post violates the rules I appoligize, and please remove it. I respect the fact that this is how most of you guys make your living, and by me doing it myself is taking work away from you or your peers.

    To start, let me give you a little background on my situation. My house in Ontario, Canada has no duct work, and I currently heat with a wood burning fireplace, and electric baseboard as a backup. We want to get duct work installed mainly for A/C in the summer, and also possibly a propane furnace for backup to our fireplace instead of the baseboards.

    We have had 4 local companies out to quote the job so we are/were open to having a company do it, but we weren't very happy with the quotes and/or methods the companies wanted to use. One company wanted to run ducts into the attic to heat the second floor. I know people do it, but we don't mind a bulk head if it means doing it right. We aren't affraid to pay good money to have it done right, but in the end we have decided if I did the duct work myself I could run things how I wanted, and hopefully save some money in the end. Then we would have a company come in for the furnace install, and hook into my duct work, so I am not completely taking work away from the industry.

    I am also paying a company to do a heat/loss and duct design and provide us with the drawings with sizes of supply and return trunks along with size and location of supply lines, and returns. Once I have that I feel very confident I can take care of everything else. Who knows, I could be kidding myself but I am willing to try.

    So now to my questions.

    1. When using a wall cavity for cold air return, is it acceptable to use a load bearing wall? Obvisouly this would require cutting out the top and bottom plates of this wall which is what I am not sure about.

    2. I have to run my main trunks through block foundation that seperates my "crawl space" (its about 5ft high) to the other side of the basement that is going to be finished. Here is a pic of each side of the block wall that I need to go through.





    Here is a further back view of the second pic..



    The plan is to basically come through that closet and angle up to run along the side of the support beam that runs the length of the basement. I have about 36" of width I can use for supply and return trunks. So is it ok to just remove the required blocks, and do I need to use something like a lintel to help carry the load?

    Thanks a lot if you read through my post and if you have time to help me out that would be great.

  2. #2
    Join Date
    Jul 2010
    Location
    nebraska
    Posts
    1,629
    A local building inspector can answer your questions when you get the permit.

  3. #3
    Join Date
    Jan 2011
    Posts
    57
    I will be getting an hvac permit, but will that inspector give me the info on the structure questions, or will that be a seperate permit?

    I realize that local building codes are my answer, I was more looking for what others have done in their area in similar situations.. Just to be prepared..

    Thanks..

  4. #4
    Join Date
    Oct 2010
    Location
    Houston, Tx
    Posts
    2,093
    Codes have barely anything to do with it, common sense does though. Think about it, LOAD BEARING and you are beneath the full load. No, you can not just cut through a load bearing wall, never, no how unless you replace said load bearing wall with some kind of temporary load bearing joist/frame until this hole you are about to cut in the main load bearing wall gets repaired.

    I don't think so. You are going to be well in over your head if you damage any load bearing wall as in entire home structure will be at risk and call Olshan type foundation repair because our house is imploding in over your head.

    Call a structural engineer and pay for an in home consultation.

  5. #5
    Join Date
    Jan 2011
    Posts
    57
    Thanks for your input.

    Just to be clear, no one said anything about cutting out a load bearing wall.. Just roughly 16" of the top and bottom plate between two studs.. I am not an idiot, and realize load bearing walls cannot be compromised.. My question was would this compromise the structure, or do people do this often?

    After doing some googling I found this company that offers a product for this very application.

    This PDF document says the following:

    Top and Bottom Plate Repair
    RPS28 – Whenever the soles or plates are cut,
    a galvanized structural repair strap that is not
    less than 16 gauge x 1⁄₂" wide is required on
    each plate and is to be fastened with 6-16d nails
    on each side of the cut.

    Common sense tells me that if the floor joists are still supported over studs, the top and bottom plate would be ok to remove, especially with these straps. I do realize the plates serve a purpose but it appears it must be common practice if they offer a prodcut to help remedy removing them.


    As far as the block wall goes I am still unsure.. I know I have seen lots of houses with blocks removed for various things like this, but I want to be sure.


    As far as I know none of the HVAC contractors I had in were structural engineers, and I know every single one of them agreed this would be the best spot to run the trunk through. I also didn't notice anything in and of the quotes that said they would be bringing a structual engineer for a consultation.

    Is this a sign of a bad contractor or is this something that needs to be done on a regular basis to accomodate this type of layout? I really don't know.

  6. #6
    Join Date
    Oct 2010
    Location
    Houston, Tx
    Posts
    2,093
    Quote Originally Posted by colesy View Post
    The plan is to basically come through that closet and angle up to run along the side of the support beam that runs the length of the basement. I have about 36" of width I can use for supply and return trunks. So is it ok to just remove the required blocks, and do I need to use something like a lintel to help carry the load?
    Can I talk to the other you again now, please?

    Call as structual engineer, not an hvac guy who knows a bit about structural, like myslelf. Whatever you do with structural will have to be engineered from start to finish, nail plates, which is what you are talking about, or not.

  7. #7
    Join Date
    Jan 2011
    Posts
    57
    I will definitely take your advice and call a structural engineer to find out about the block removal.

    So yourself as an HVAC Professional, or any other person that you would consider reputable, how would you handle this situation with a client? As I said, none of the 4 companies I had come and quote mentioned anything about consulting anyone about this.

    Again, thanks for you help. I appreciate it.

  8. #8
    Join Date
    Oct 2010
    Location
    Houston, Tx
    Posts
    2,093
    As far as I have been led to understand, when making any kind of adjustment to a load bearing wall, the load which is going to be removed, even if on side joists/plates, needs to first be calculated and then something needs to be built/installed to hold that weight in it's place BEFORE cutting anything.

    I can't say about those replacement plates you found, not sure if they are meant to permanently carry even a partial load.

  9. #9
    Join Date
    Jan 2011
    Location
    10 miles west of New York City
    Posts
    2
    If you really looking for just AC, install it in the attic is simpler and more effective choice. Cool air is heavier., and it will flow down. My friend's house in Houston has that setup. I ended up installed a second just AC system with multiple returns in my attic about 2 years ago. It works great. Recently learn that one of my friend's 3K sq two levels home have single AC only in the second floor, and has baseboard heat on both floors.

    Have fun.

  10. #10
    Join Date
    Oct 2010
    Location
    Houston, Tx
    Posts
    2,093
    Quote Originally Posted by colesy View Post
    I will definitely take your advice and call a structural engineer to find out about the block removal.

    So yourself as an HVAC Professional, or any other person that you would consider reputable, how would you handle this situation with a client? As I said, none of the 4 companies I had come and quote mentioned anything about consulting anyone about this.

    Again, thanks for you help. I appreciate it.

    I've never had to deal with basement load bearing walls my entire time in this field or any field. We don't have basements here, we have attics where all the duct work is located and supplies come from the ceiling, but I'd be guessing that the guys in your area are either doing their homework as we speak IF they were planning on going through the same wall (you said they wanted to do something else, right?) or know something I don't, being up where you are.

  11. #11
    Join Date
    Jan 2011
    Posts
    57
    Ahh right.. That makes sense.. I forgot that a lot of homes further south don't have basements.. Pretty much every house has at least a crawl space in this area, and most with full basements anymore.

    I guess if they deal with this on a daily basis they would have a good idea of how to deal with it.. Good point.

  12. #12
    Join Date
    Oct 2010
    Location
    Houston, Tx
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    2,093
    Quote Originally Posted by uid60001 View Post
    If you really looking for just AC, install it in the attic is simpler and more effective choice. Cool air is heavier., and it will flow down. My friend's house in Houston has that setup. I ended up installed a second just AC system with multiple returns in my attic about 2 years ago. It works great. Recently learn that one of my friend's 3K sq two levels home have single AC only in the second floor, and has baseboard heat on both floors.

    Have fun.
    What's up with the sudden explosion of newbs posting first on this thread, all saying my name and talking about my city? of course your "friend" has his system in the attic, everyone does here, duh.

  13. #13
    Join Date
    Jan 2011
    Posts
    57
    Quote Originally Posted by uid60001 View Post
    If you really looking for just AC, install it in the attic is simpler and more effective choice. Cool air is heavier., and it will flow down. My friend's house in Houston has that setup. I ended up installed a second just AC system with multiple returns in my attic about 2 years ago. It works great. Recently learn that one of my friend's 3K sq two levels home have single AC only in the second floor, and has baseboard heat on both floors.

    Have fun.
    My post might be a little misleading.. All though I said the duct work was mainly for A/C we do still plan on installing some sort of heat source source as well, most likley propane (no natural gas my way).

    I completely agree that registers in the ceiling would make sense if it was just A/C.

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