Furnace too large? - Page 2
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  1. #14
    Join Date
    Nov 2005
    Location
    Northern VA
    Posts
    512
    There is no Infinity 90% furnace with a capacity of less than 40K. What are the exact dimensions of the available space? If they haven't finished building it yet, any chance they could bump one of the walls out a little?

  2. #15
    Join Date
    Nov 2005
    Location
    Berkeley, CA
    Posts
    17
    Perel

    The space available is 39" wide and 36" deep [sharing an 8' wall with a washer & dryer, each 27" wide.]

    The rectangular main supply duct will run beneath the ceiling, over the washer & dryer. The 2nd floor return will be in the joist space between floors, just above the supply.

    My HVAC-calc shows 22" X 8" for the Supply, and 18" X 6" for the 2nd floor return. I think the plan was for the 2nd floor return to come down on the right side of the furnace cabinet, joining a plenum (?) box beneath the furnace- which would also contain a register for the 1st floor return.

    The main supply duct would come of the top left of the cabinet.

    Today, "Mr. No J" said that the 40,000 BTU Infinity definitely would not fit, and is offering me a Tempstar unit as an alternative.

    It seems to me that even the 24.5" cabinet should fit...

  3. #16
    Join Date
    Nov 2005
    Location
    Northern VA
    Posts
    512
    Ah. He's worried about the 90-degree elbow where the vertical drop meets that plenum box not leaving enough space for the furnace. It would be tight, but might be doable.. hopefully someone can confirm if that is possible or not. (Would 14.5" be enough for a square 90 elbow + turning vanes?)

  4. #17
    Join Date
    Nov 2005
    Location
    Berkeley, CA
    Posts
    17

    Confused

    Our confusing saga continues...

    After many calls over the past week, I finally got a 2nd HVAC tech to come by for another opinion. They only offer Carrier, but they're a large, big city operation, so I expected a bit more engineering to go along with the higher costs.

    The estimator took a look at my HVAC-Calc pages (Total Heat Gain: 29,590
    Total Heat Loss: 23,551 [28,261 with 20% safety factor]), and laughed. He said his company did Manual J's, but "they never work".

    He recommended a 100,000BTU furnace and 4 ton AC unit, because they "always oversize", and with 13 registers, we need lots more airflow than the 60,000BTU Infinity can provide.

    Needless to say, since this guesstimate is in the opposite direction of what I was expecting [size-wise], I'm still trying to get more estimates, with only days to spare.

    If anyone can recommend someone, or, better yet, if any of you knowledgeable Forum members works anywhere near Berkeley, CA, I'd be grateful to hear from you!

  5. #18
    Join Date
    Nov 2004
    Posts
    2,927
    Originally posted by pableau
    Our confusing saga continues...

    I'm still trying to get more estimates, with only days to spare.

    If anyone can recommend someone, or, better yet, if any of you knowledgeable Forum members works anywhere near Berkeley, CA, I'd be grateful to hear from you!
    yes, keep looking. the big guys are not always better.


    Irascible is from California and he's definitely a liberal
    but I dont know if he's from Berkley or not.



    start a thread that says "looking in berkley calif."
    you are allowed to do that
    Sometimes there are compounding complexities of multiple variables that are not intuitively obvious

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