Announcement

Announcement Module
Collapse
No announcement yet.

pressure for temperature gradient

Page Title Module
Move Remove Collapse
X
Conversation Detail Module
Collapse
  • Filter
  • Time
  • Show
Clear All
new posts

  • pressure for temperature gradient

    I am adding a duct/fan to bring hot air from a loft area down to the floor of the main level, in order to help reduce heating costs (and possibly, in summertime, to make the loft area more livable.

    I'm trying to figure the pressure the fan (probably a Fantech FR series) is going to be working against. The CFM of the fan drops off as the pressure head increases, but it doesn't get too significant until about 0.5" H2O, so I'm trying to figure out how much. The duct calculator says I should be below 0.2" or so. But since I'm sucking quite hot air downwards about 15ft, that's going to add some pressure over and above the friction loss in the ductwork. But I have no idea how to figure out how much. Thanks.

  • #2
    Re: pressure for temperature gradient

    Sorry to say this but i see your an Engineer and i say your putting to much thought into this .
    I have Chalet and it has two lofts one open and one closed . The closed one has a window at the top to let the air in and the cold air out the door at the bottom .
    Im going to close of the other loft but the stairs are in the main room so there will be a door up top with a window on the other end of the wall up high .
    i have a wood stove going with a ceiling fan at low speed so the air goes up the center and down away from the fan . Under the open loft is the kitchen , bed room with a window into the big room , the bath and mud room . there is a ceiling fan in the kitchen and that room is open to the big room . I put that fan on med and it moves the are into all the rooms under the open loft .
    Some times simple is better .
    Charlie

    My seek the peek fundraiser page
    http://observatory.mountwashington.o...nal&fr_id=1040


    http://www.mountwashington.org/weather/conditions.php

    new work pictures 12/09
    http://public.fotki.com/hvachawk/

    Comment


    • #3
      Re: pressure for temperature gradient

      Originally posted by HVAC HAWK View Post
      Sorry to say this but i see your an Engineer and i say your putting to much thought into this .
      Hah ! Nothing wrong with thinking ...
      i have a wood stove going with a ceiling fan at low speed so the air goes up the center and down away from the fan .
      Yes, that's exactly what I do. But I now want to use the hot air in the loft to help heat the new room I'm adding in the rear of the house and to circulate air through where I'm putting the new ultra-efficient mini-split heat-pump.

      For the record, in another forum I'm told that what I'm asking about is called "stack effect" and is probably 0.02"WC at the most.

      Comment


      • #4
        Re: pressure for temperature gradient

        Im not good with all the numbers i just know how to get air to where i need it .
        Im thinking of using a in line fan in a round duct to get air to a far room .it will be controlled with a thermostat
        Charlie

        My seek the peek fundraiser page
        http://observatory.mountwashington.o...nal&fr_id=1040


        http://www.mountwashington.org/weather/conditions.php

        new work pictures 12/09
        http://public.fotki.com/hvachawk/

        Comment


        • #5
          Re: pressure for temperature gradient

          Originally posted by RustyShackleford View Post
          ... called "stack effect" and is probably 0.02"WC at the most.
          Think as well that you are way over thinking this. People fart .02" WC easily.
          ~~

          ... it was plumbed by Ray Charles and his helper Stevie Wonder

          Comment

          Working...
          X