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Thread: Death Trap

  1. #1
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    Death Trap

    Note the Carrier Infinity 100 MBtu Furnace with a draft inducer vented with 6" Double wall B vent and a draft hood with spill switch.

    Been that way for a few weeks and has a plumbing inspection sticker on it.

    I am guessing that there was an inspector who had it in for the installer and made him do all this to make him happy. I cannot think of any other reason why a contractor would deviate from the Carrier manual and put in 6" B vent.

    Insanity
    Last edited by numbawunfela; 10-13-2010 at 07:32 PM.
    Hmmmm....smells like numbatwo to me.

  2. #2
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    If that B vent goes into an unlined masonry chimney, that is a proper installation. If the chimney has a metal liner or is constructed of B-vent, the draft hood accessory is unneeded.

  3. #3
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    Thread Starter
    Quote Originally Posted by craig1 View Post
    If that B vent goes into an unlined masonry chimney, that is a proper installation. If the chimney has a metal liner or is constructed of B-vent, the draft hood accessory is unneeded.
    I will not pretend to be a code expert, but....

    Blowing into a flue with a big hole in it is safe? I understand that properly drafting appliances that are Cat II- even with a draft inducer - will produce a negative pressure in the flue, but this seems a bit odd. I have only been around the block 1 or 2 times, but I have never seen or heard of anything like this.

    Are you SURE?

    Also we here in Jersey have been lining pretty much any exterior chimney - is it possible to avoid this if we install with a draft hood and spill switch?

    I am willing to admit I am wrong in thinking this is a bad install - but I would like to know where I am off, that is all.
    Hmmmm....smells like numbatwo to me.

  4. #4
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    I've never seen anything like that. In fact, I know of no manufacturer who allows for an vent installation where the front cover of the furnace cannot be attached. Clearly this installation prevents the front cover from being installed. I'd label it hack work, personally. I'm trusting that this is an 80% AFUE gas furnace?? If so, it would should be vented with 4-inch single wall, at least to the exterior of the jacket. I believe the National Gas Code calls for B-vent between the appliance and the chimney in non-traffic areas, such as attics and crawl spaces. Other times, such as in closets and/nor stand-up basements, single wall is allowed, provided distances to combustibles are maintained.
    If YOU want change, YOU have to first change.

    If you are waiting for the 'other guy' to change first, just remember, you're the 'other guy's' other guy. To continue to expect real change when you keep acting the same way as always, is folly. Won't happen. Real change will only happen when a majority of the people change the way they vote!

  5. #5
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    Cool Carrier chimney adapter

    If this is a CAT I Carrier 80% furnace with their listed chimney adapter then this is probably to their instructions. The chimney adapter is an attempt by Carrier to allow venting of draft induced furnaces into exterior masonry chimneys without relining. However, if you read the fine print, it clearly states the chimney must meet NFPA 211, which none do. Therefore, ALL chimneys must be lined with a listed liner system or B-vent.

    FYI, Cat II is a theoretical category. It is supposedly natural draft but operates below dewpoint so there really is not enough stack loss to generate a natural draft. Cat III is your typical tankless water heater and some older condensing boilers while Cat IV is your 90% or better condensing boilers and furnaces. Cat III and IV operate under positive flue gas pressure so they cannot be vented into a chimney or B-vent. There is one liner listed under UL 1738 for Cat IV but it is seldom used. All the other chimney liners cannot be used for Cat III or IV appliances.
    HTH,

  6. #6
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    Thread Starter
    Quote Originally Posted by skippedover View Post
    Clearly this installation prevents the front cover from being installed.
    Actually the front cover is very deep and pops over that whole mess. the elbow is from carrier, and up until it meets the 4" to 6" transition (before the hood), it is from the manufacturer. I wll try to put up a link to the manual for the furnace. I went through the manual that I could find on the web and it said nothing about draft hoods or spill switches.

    I have never been a fan of Carrier stuff because from Commercial on down their equipment always seemed over-engineered. But that is another topic.
    Hmmmm....smells like numbatwo to me.

  7. #7
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    Possible Reason for 6" Type B vs 4" Type B:
    Existing 6" pipe installed and the Inspector allowed it with a sillage switch installed. Still not a correct install, but sounds like something an inspector would come up with. Just Saying.

  8. #8
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    The masonry chimney kits are only available is certain sizes...........reminds me of a job that needed one and the low bidder (who did not put one in) got the job since he did not comply with the installation instructions.
    I wish I had a $1.00 for every response I deleted.....

    "Decidedly Superior in a twisted pathetic way".....

  9. #9
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    The book for that furnace says the 4 inch must be increased to 5 inch. Also the 2stage must have a bvent vent connector. If you don't increase it the little switch on the 4 inch will open. I made that mistake.then read the book.

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