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  1. #1
    Join Date
    Mar 2007
    Location
    Central Ohio
    Posts
    16

    Do I really need a 5 ton furnace?

    I live in a cinder block home shaped like an H (every wall is exterior) and the walls are only about R10 and square footage only 2250. We currently have a 5-ton York Pulse furnace (I think 90,000 Btu). The house is circa 1940 and is in desperate need of some reducting (long, long runs where there probably should be more of a trunk built out). Anyway, I'm clearly not a pro, but what are the factors to consider when considering the "tonnage" of a furnace?

  2. #2
    Join Date
    Aug 2006
    Location
    oak park,ill
    Posts
    51
    Quote Originally Posted by dave_scarpetti View Post
    I live in a cinder block home shaped like an H (every wall is exterior) and the walls are only about R10 and square footage only 2250. We currently have a 5-ton York Pulse furnace (I think 90,000 Btu). The house is circa 1940 and is in desperate need of some reducting (long, long runs where there probably should be more of a trunk built out). Anyway, I'm clearly not a pro, but what are the factors to consider when considering the "tonnage" of a furnace?
    You should start with a manual j load calculationand have an in depth Energy Audit done by a Professional to see ways to improve.We can't tell u whats needed without looking.Gone are the days of Rule of thumb sizing and if u have issuses with your ductwork you'll need that fixed as well to ensure proper operation.

  3. #3
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,376
    What silkysean said. In addition, furnaces are not rated in "tonnage"; whereas the condenser of a common residential split system that would have a cooling coil at the furnace is.
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

  4. #4
    Join Date
    Mar 2007
    Location
    Central Ohio
    Posts
    16
    Thanks. I had a pro out recently and when I asked, he said he did Manual J calcs to support his proposal. I wish I understood them. The crude scheme is going to look like this.

    And for this, he suggested a Lennox G61V. I definitely should have an energy audit done as well.

    Thanks again for the input.

  5. #5
    Join Date
    Jul 2006
    Location
    Lancaster,Ohio
    Posts
    464
    I would study up on the lennox thing before you commit! A Five ton drive (the size of blower and motor) on a furnace may be required to move all the air around the corners. A load calc will tell you how many BTU's you need for heating and how many 'tons' of cooling you need.
    IcyFlame

  6. #6
    Join Date
    Jul 2006
    Location
    Virginia
    Posts
    4,903
    you might consider 2 systems.

  7. #7
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,432

    Angry

    Quote Originally Posted by dave_scarpetti View Post

    I live in a cinder block home shaped like an H ...
    ... The house is circa 1940 and is in desperate need of some reducting
    The last 10,00 pound furnace was installed circa 1908.
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  8. #8
    Join Date
    Apr 2004
    Posts
    7,680
    Yeah, and I took it out and have the back ache to prove it.

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