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  1. #27
    Join Date
    Feb 2007
    Location
    Great Lakes Region
    Posts
    566

    Confused

    I really should stay out of this, but need to get some posts to get into the pro forums. Where are you getting this 50% more efficiency? Is there a formula I missed?

  2. #28
    Join Date
    Feb 2004
    Location
    chicago suburbs
    Posts
    4,422
    ..he's pulling it out of his a$$.













    no formula.

  3. #29
    Join Date
    Mar 2008
    Location
    Long Beach, CA
    Posts
    3,147
    Quote Originally Posted by kamikaze126 View Post
    I really should stay out of this, but need to get some posts to get into the pro forums. Where are you getting this 50% more efficiency? Is there a formula I missed?
    When a heater is able to raise room temperature in half the time because of an improved ducting system you have increased the system efficiency and energy savings by 50%.

    Brian

  4. #30
    Join Date
    Mar 2008
    Location
    Long Beach, CA
    Posts
    3,147
    Quote Originally Posted by tinner73 View Post
    ..he's pulling it out of his a$$.

    no formula.
    The formula is: temperature change divided by energy consumption. Are you keeping up, or should I dumb it down?

  5. #31
    Join Date
    Feb 2007
    Location
    Great Lakes Region
    Posts
    566
    and you feel the room temp is being raised in half the time due to pulling down the hot air from the ceiling instead of it eventually mixing on its own?

  6. #32
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    If the funace cycles half as long... is it cycling twice as often?

    Unless you've altered the heat loss properties of the structure, you will still need the same BTU's to heat it. The savings would be from distributing heat more evenly allowing a lower setpoint to be used and reducing temperature swings.

    I read several papers thsi morning regarding duct design and all menton that while it's optimum ot have a high return for cooling and low return for heating, ultimately return placement has a relatively small impact. As the pro's on this board have said, it's the velocity and mixing affect of the supplies that heat the home along with in large part conduction. A return won't pull air down from the ceiling or draw air from across the floor. A supply however CAN do this.

  7. #33
    Join Date
    Mar 2008
    Location
    Long Beach, CA
    Posts
    3,147
    Quote Originally Posted by kamikaze126 View Post
    and you feel the room temp is being raised in half the time due to pulling down the hot air from the ceiling instead of it eventually mixing on its own?
    Yes, because it typically does not mix on its own.

  8. #34
    Join Date
    Feb 2007
    Location
    Great Lakes Region
    Posts
    566
    so... the heat stays at the ceiling for too long, resulting in a 50% loss because no matter how well the house is insulated it can only hold back the ceiling heat for so long?

  9. #35
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    66,804
    Quote Originally Posted by Brian GC View Post
    I've made them out of ply and MDF but this one is strictly temporary to prove a point. It will be removed in a few months. BTW, although it slightly restricts inflow, it is still a major improvement.

    Brian
    Go to Hart&Cooleys website.

    Download their catalog, and engineering sheets.

    Altering the return as you do, is a cover up. It covers up poor distribution selection.

    It actually proves the importance of proper supply grille/register selection.


    In this area, we use floor supplies and floor returns for both heating and cooling.
    Contractor locator map

    How-to-apply-for-Professional

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

  10. #36
    Join Date
    Mar 2008
    Location
    Long Beach, CA
    Posts
    3,147
    Quote Originally Posted by kamikaze126 View Post
    and you feel the room temp is being raised in half the time due to pulling down the hot air from the ceiling instead of it eventually mixing on its own?
    Let me clarify further. Warmer air near the ceiling is not “pulled down”, it naturally descends do to the floor because the colder floor air is being removed. Inversely, if the warmer air near the ceiling is being removed the opposite will occur. As the warmer air is removed, the colder floor air will naturally rise or occupy more space.

    Trying to mix all the air to eliminate stratification is a pipe dream. Lowering a return to get the most out of your heater is step one, trying to mix air is the band-aid for improper ductwork.

    The reason the Pro defends ceiling returns is because:
    They are easy to install.
    They are unwilling or unable to explain the benefits of floor returns on heaters.
    They do not want to do the extra work for limited compensation.
    Their competition is not bidding for that work, so they won’t.
    The architect and GC regularly do not demand it.
    They may not know what a dual duct system is.
    They are trying to keep the price down.

    But rather than face these realities, it is easier to just point to a ‘Manual’ or a magic supply register.

    Like I said before, I’d love to take the money from any Pro who would bet me.

    Brian

  11. #37
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    66,804
    More like, GC's won't pay for it.
    Contractor locator map

    How-to-apply-for-Professional

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

  12. #38
    Join Date
    Feb 2004
    Location
    chicago suburbs
    Posts
    4,422
    you've gotta post a pic of your revolutionary invention.

  13. #39
    Join Date
    Jan 2009
    Location
    NC
    Posts
    27
    I like motoguy it is all about the BTU's

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