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  1. #79
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    Apr 2002
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    11,808
    Next time you go to a kid's birthday party steal a candle from the cake.

    Hold it a foot from your yap and lightly blow. Unless you have emphasema, that flame will be extinguished.

    Re-light that candle and again hold it a foot away. Breathe in as hard as you can. Flame still burning huh.

    Well move the candle a little closer but be careful not to exhale on it. Still lit, move it a little closer and try again..

    See if by the time you can extinguish it by inhaling you end up burning your lips.
    The way we build has a greater impact on our comfort, energy consumption and IAQ than any HVAC system we install.

    http://www.ductstrap.com/

  2. #80
    Join Date
    Nov 2000
    Location
    Eastern PA
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    68,981
    Originally posted by Carnak
    Next time you go to a kid's birthday party steal a candle from the cake.

    Hold it a foot from your yap and lightly blow. Unless you have emphasema, that flame will be extinguished.

    Re-light that candle and again hold it a foot away. Breathe in as hard as you can. Flame still burning huh.

    Well move the candle a little closer but be careful not to exhale on it. Still lit, move it a little closer and try again..

    See if by the time you can extinguish it by inhaling you end up burning your lips.
    Ohhhh you are a clever one carnak. I would never have been able to think up such a clever way to get the "suck" advocators to burn their lips like that
    Government is a disease...
    ...masquerading as its own cure…
    Ecclesiastes 10:2 NIV


  3. #81
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    Mar 2004
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    Ah. nice try grasshopper, but your experiment is flawed.

    Take a candle, and hold it a foot away from your mouth. Hold your mouth WIDE open just as you did when you “SUCKED” air in. Now blow as hard as you can to blow the candle out. Keep moving closer repeating, and you will burn your own lips grasshopper.

    See robo, my theory doesn’t “suck” after all does it?

    Go back to the drawing board guys.

    I told you this is going to be good for another 20 pages.

  4. #82
    Join Date
    Apr 2002
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    11,808
    Sorry, unsucessful at snatching the pebble from my hand.

    Still goes out, have to blow a little harder.

    Try puckering up your lips a bit when you inhale to increase your capture velocity. Practise the lip formation on banana.

    The way we build has a greater impact on our comfort, energy consumption and IAQ than any HVAC system we install.

    http://www.ductstrap.com/

  5. #83
    Join Date
    Nov 2005
    Location
    On Tour or Central FL or Michigan
    Posts
    49
    Hum,
    The push-me-pull-you of HVAC

    I wouldn't have tried to suck the candle out with my mouth wide open, othwies how would I burn my lips?

  6. #84
    Join Date
    Nov 2000
    Location
    Eastern PA
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    68,981
    It will only go for another 20 pages because you are too stupid to understand when you are wrong. I can understand that you "suck" and "blow" with your mouth wide open as a natural thing to do, but I can certainly suck air with a very closely pursed lips. But then again, that thought has probably gotten you more excited then you deserve to be.

    You realize that you are not only arguing with experts but one who in a single thread has proposed stealing from a local bar and a kid's birthday cake. You are just out of your league here maiden. Unfortunately you will continue to boor us with more mundane posting because you don't understand that you have no argument.

    Lets see now; we have no clue as to anything about you, including your occupation, gender, location or affiliation with anything in the HVAC trade, yet we do know you are a boisterous conservative.......OH MY!!! You could be Ann Coulter! Is this your way of getting off on a sexual fantasy Ann? You are one sick beeech.
    Government is a disease...
    ...masquerading as its own cure…
    Ecclesiastes 10:2 NIV


  7. #85
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    self edit, see below

    [Edited by madeinusa on 11-30-2005 at 12:38 AM]

  8. #86
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    self edit. you got the message.

    [Edited by madeinusa on 12-01-2005 at 12:31 AM]

  9. #87
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    Sorry for the rude interruption Carns.

    I did think about velocity while inhaling and increasing velocity like you said.

    I also know it is not possible to develop as much velocity inhaling when you are “sucking” from basically the whole atmosphere.

    If you put a 5 foot straw in your mouth and recorded the velocity “at” your mouth while inhaling, and also recorded it while exhaling, it would probably be very close. Maybe not, being you are able to squeeze your lungs harder with muscles to exhale, than your ability to use your muscles to inhale.

    Basically you are attempting this experiment at two different locations. Exhaling, the oxygen is coming out through a small duct system, your windpipe, and building velocity, yet when inhaling, the air is not coming through a duct system.

    To get a truer reading you should measure at the entrance to the lungs while exhaling and inhaling.


    [Edited by madeinusa on 11-30-2005 at 04:17 AM]

  10. #88
    Join Date
    Oct 2005
    Posts
    923

    Static vs Design

    . The fan size, RPM, blade shape, Return duct size, Supply duct size, Filter size. And such. All have been designed for delivering a maximum specific amount of air with the ability to deliver a maximum specific temperature, under certain atmospheric conditions.

    To do as one pleases would be speculation, yet I do realize that it is not cost effective or reasonable to do every single thing by the book. A lack of designed return air will place a drag on the motor and may require more hp. An increase in return air will affect temperature and efficiency. Some returns require plenum gravity. Others require fan forced air.

    I come from a forced air home. A room was to hot close down on the room deffusser, room to cold open it up. It works but it is the same as the candle test. Works but to what degree and all the variables are missing from the equation. How much money going out the window.

    Later on I Chose to install hot water but if I did do air for my self you can bet that system would receive not only a load for the full house but every inch of every room including btu absorbing decorations ,furniture and such. Including gage of duct and size of duct and the supply return with every diffuser balanced. You only should need to do it one time and forget it forever.

    You could think of it this way, would you guess at how much your paycheck is? Or did you sit own and check to see if that you had been told hourly was actually in the check.

    Like that quote some one has, measure twice cut once.

  11. #89
    Join Date
    Apr 2002
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    11,808
    Originally posted by madeinusa
    Sorry for the rude interruption Carns.

    I did think about velocity while inhaling and increasing velocity like you said.

    I also know it is not possible to develop as much velocity inhaling when you are “sucking” from basically the whole atmosphere.

    If you put a 5 foot straw in your mouth and recorded the velocity “at” your mouth while inhaling, and also recorded it while exhaling, it would probably be very close. Maybe not, being you are able to squeeze your lungs harder with muscles to exhale, than your ability to use your muscles to inhale.

    Basically you are attempting this experiment at two different locations. Exhaling, the oxygen is coming out through a small duct system, your windpipe, and building velocity, yet when inhaling, the air is not coming through a duct system.

    To get a truer reading you should measure at the entrance to the lungs while exhaling and inhaling.


    [Edited by madeinusa on 11-30-2005 at 04:17 AM]
    If you kept the lip position the same, perhaps to accomodate a big dill pickle, and breathed in and out at the exact same rate, you will be able to exhale and blow out the candle every time and but you will not be able to extinguish the flame by inhaling.

    The velocity through your lips is the same in each case just the direction of the air flow is opposite.

    So the little experiment shows that pressure differential causes air to move from areas of high pressure to lower pressure, and return air to a fan inlet will chose the path of least resistance. You were sucking air from directly in front of your lips, the minute amount of air that travels past the flame was ineffective.

    Your straw demonstrates exactly what a ducted return can do, gives you control as to the path back to the fan. With a straw, you can have the candle away from your face and would still be able to extinguish it.

    There is a point where the straw will become too long and you will not be able to inhale and extinguish that flame, but using the same length straw you will still be able to blow it out with out having to cough a lung out to build up enough pressure to do so.

    Kitchen hoods do not hoover the grease fumes from a cook line, they have to remove air from the hood at, at least the same rate that the thermal uplift from the heated cooking surfaces causes the greasy fumes to rise up into the hood.
    The way we build has a greater impact on our comfort, energy consumption and IAQ than any HVAC system we install.

    http://www.ductstrap.com/

  12. #90
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
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    18,836
    The birthday candle diffrence is about velocity of the air,really doesn't speak to the discussion.IMHO.

  13. #91
    Join Date
    Aug 2002
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    Office and warehouse in both Crystal River & New Port Richey ,FL
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    Originally posted by RoBoTeq


    The return air portion of an HVAC ducting system does not "pull" or "suck" air...it allows the higher pressure of air introduced into an area to "return" to the units blower.


    "it allows the higher pressure of air introduced into an area "

    That sounds like what you have stated before ,that the supply air pushes the air to and/or thru the return.


    Question,if we have place paper over part of the return grille,it stays in place rather firmly.So is it being held their by the supply air pushing it,atmospheric pressure ,or suction from the fan????

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