Page 2 of 2 FirstFirst 12
Results 14 to 20 of 20
  1. #14
    Join Date
    Aug 2009
    Location
    Beatrice, NE
    Posts
    10,055
    Post Likes
    Let me start by saying something most on here will yell at me about but flex is not bad, just misapplied. Flex duct will move about 20% less air than the same size metal so if sized correctly will move the air just fine.

    From reading your situation you are going to close in the duct in conditioned space, why spend the extra money on insulation, it just takes up more space.

    It sounds like your new system is oversized by 1 maybe 2 sizes depending on actual load. Make sure you have the right sized system before you put in wrong sized ducts to support the equipment.

    If you have concerns with getting the right amount of air to the far end of the house put in a zoned system with the far end being a zone. This can be a multi edged sword though. Most companies have a hard time getting regular duct correct without adding in the complications of zoning.

    Properly designed and installed duct will have the ESP needed for the equipment to operate efficiently. Find the dealer that understands air flow and is willing to do all the calculations to get the system right for you and the house.

  2. #15
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    9,727
    Post Likes

    RULES FOR EACH HALF-DECADE or So + per Quality Built

    NO One Here Wishes to use the RULES-OF-THUMB for A/C SIZING.

    I would definitley review them in the CONCEPTUAL DESIGN PHASE.

    _ A.K.A. _ BALL PARK ESTIMATING ...

    I.E. ... RULES GALORE ...
    ___ 1999 BUILT ... 698 to 901 SQ. FT. /TON

    THE REAL ISSUE with using RULES
    is that many in this industry are 'stuck in' the 1950's mentality.

    ... ___ … 2020 Built: 800 to 1,037 & Beyond _ Sq. Ft per Ton
    Attached Images Attached Images
    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

  3. #16
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    9,727
    Post Likes
    The EL of each duct fitting/ component should be < 35.

    60' x 30' perimeter
    ____ _ _ _ It should actually be Quite Difficult to build a Supplt Air duct system with > 300 TEL.
    ____ _ _ _ The Extreme distant run should have < 6 turns.
    _____ Maintian Velocity < 560 FPM in Branches; < 1000 FPM in Header

    Use one system per floor:
    _____ will not be a great deal more $$$ than a multi zone system
    _____ follows the KISS principle for Relialbe System Operation
    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

  4. #17
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    9,727
    Post Likes

    1410 CFM

    MORE SPECIFIC GUIDANCE / GOAL

    ___ EXAMPLE : ESP 0.69"
    _____________

    ... = SUPPLY + RETURN = TOTAL
    TEL = __ 286 + __ 98 = __ 384 .:. 0.05" / 100 FEET


    34,400 BTU/HR Q. Sensible C- Btuh Cooling based on ACCA Manual J Block Load

    1,800 SF + Basement for NW Philly Pa
    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

  5. #18
    Join Date
    Jan 2004
    Location
    PA
    Posts
    78,337
    Post Likes
    I'm trying to figure out why you have such a big furnace for an 1800 sq ft house.

    You probably don't need more than a 70,000BTU furnace.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  6. #19
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    9,727
    Post Likes
    Quote Originally Posted by beenthere View Post
    I'm trying to figure out why you have such a big furnace for an 1800 sq ft house.

    You probably don't need more than a 70,000BTU furnace.
    Post # 7 BLUE SCRIPT : 1,800 Sq Ft Living Area
    __ ____________ AND _ 1,800 Sq Ft Basement / Two sides exposed to air

    with very limited BUILDING THERMAL ENVELOPE Description
    ___ 1999 Built
    ___ 48,100 BTU/HR at 15'F for ZIP 19063

    ... might need A 4-Ton, 2-Stage A/C System
    ... if the infiltration is medium-high
    ... AND 560 total square feet of glass.

    OF COURSE, TWO Independent systems seems to be the best approach.
    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

  7. #20
    Join Date
    Aug 2009
    Location
    Beatrice, NE
    Posts
    10,055
    Post Likes
    Quote Originally Posted by beenthere View Post
    I'm trying to figure out why you have such a big furnace for an 1800 sq ft house.

    You probably don't need more than a 70,000BTU furnace.
    Because there are still those that believe bigger is better and they don't consider the better insulation and tighter home that are built now.

Page 2 of 2 FirstFirst 12

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •