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  1. #14
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    Jan 2005
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    I think I understand now (thanks too to dash..).

    Usually you have both supply and return duct work in the attic in Florida homes. In your case the return is apparently right next to the air handler (on the other side of the garage wall in the hallway). So in this installation your return duct heat gain would be very very small.

    The 55.9 degree temperature was the supply plenum temperature.

  2. #15
    Join Date
    Apr 2005
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    83
    Originally posted by travisfl
    I think I understand now (thanks too to dash..).

    Usually you have both supply and return duct work in the attic in Florida homes. In your case the return is apparently right next to the air handler (on the other side of the garage wall in the hallway). So in this installation your return duct heat gain would be very very small.

    The 55.9 degree temperature was the supply plenum temperature.
    Good because you 2 were getting me confused, but the way you have it now is correct.

    Ok so 55.9 at the supply plenum yet 62.5 at the returns, is this a problem or can I suck that up to attic heat?

    Felix

    [Edited by nyrfan on 07-12-2005 at 12:32 PM]

  3. #16
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    Jan 2005
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    340
    Originally posted by nyrfan
    Ok so 55.9 at the supply plenum yet 62.5 at the returns, is this a problem or can I suck that up to attic heat?
    That's heat gain from the attic, and it is excessive if the duct run is 25' or less. What are your ducts made of, and how far is it from the air handler to the first supply register?

  4. #17
    Join Date
    Apr 2005
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    83
    Originally posted by travisfl
    Originally posted by nyrfan
    Ok so 55.9 at the supply plenum yet 62.5 at the returns, is this a problem or can I suck that up to attic heat?
    That's heat gain from the attic, and it is excessive if the duct run is 25' or less. What are your ducts made of, and how far is it from the air handler to the first supply register?
    About 7 feet to the first register but this has 0 insulation around it. Hard to explain but in short in runs above the outside entranceway (inside the roof of course), from the garage over the entranceway to the 1st room. The furthest room return is about 25 ft away and has the same reading of 62.5

    As for the type, not sure what is called but it looks like a big round garbage bag.

    Felix

  5. #18
    Join Date
    Jan 2005
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    340
    Originally posted by nyrfan
    The furthest room return is about 25 ft away and has the same reading of 62.5

    As for the type, not sure what is called but it looks like a big round garbage bag.
    Sounds like flex duct, probably R-6 rated.

    I'm surprised that the closest register still has that much heat gain. How and where are you measuring the temperature (just inside the register in the middle of the airflow is best, after the system has been running 20 minutes or more).

  6. #19
    Join Date
    Apr 2005
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    83
    Originally posted by travisfl
    Originally posted by nyrfan
    The furthest room return is about 25 ft away and has the same reading of 62.5

    As for the type, not sure what is called but it looks like a big round garbage bag.
    Sounds like flex duct, probably R-6 rated.

    I'm surprised that the closest register still has that much heat gain. How and where are you measuring the temperature (just inside the register in the middle of the airflow is best, after the system has been running 20 minutes or more).
    Defiantly running over 20 minutes but probably not in the middle of the return more towards the front of it using a digital thermometer with a +/- 1 differential. I can do it again when I get home.

    Do you think because there is such high heat gain there could be a leak somewhere or one has nothing to do with the other?


  7. #20
    Join Date
    Jan 2005
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    340
    Originally posted by nyrfan
    Do you think because there is such high heat gain there could be a leak somewhere or one has nothing to do with the other?
    It's not likely that the heat gain is caused by a leak since the supply ducts are under positive pressure. Most likely it is just poorly insulated flex duct (see if you can see an R-value rating stamped on the covering). About your only options are to lower the temperature in the attic (install more ventilation...power ventilators don't usually save more energy than they consume) or add insulation to the existing duct work (and it would probably be cheaper just to replace it with a better quality flex).

  8. #21
    Join Date
    Apr 2005
    Posts
    83
    Thank you Travis, will go up there when I get home from work and let you know if I see a rating. I'll post a little later on again.

    Just out of curiosity: Where the handler comes though in the attic is the 100% not “insulated” attic above the garage, could the gain be happening there on the supply plenum as it’s called? I measured the temp of the supply plenum closest to the handler in the garage not in the attic right before the break off point. Maybe there is too much heat in that section (The attic above the garage)? The is no attic vent on that side of the house and it’s (The garage) almost fully closed off with insulation and plywood from the rest of the house if that makes any sense.

    See this link for a picture of the house to maybe understand better:

    http://a7.cpimg.com/image/33/4B/2930...-02000180-.jpg


    Thanks again for the advice.

  9. #22
    Join Date
    Jan 2005
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    340
    Originally posted by nyrfan
    Where the handler comes though in the attic is the 100% not “insulated” attic above the garage, could the gain be happening there on the supply plenum as it’s called?
    Certainly, if the plenum isn't insulated.

    Florida Building code requires that the garage plenums be sheet metal up through the point where they penetrate the wall / ceiling, so I assume yours is? I also would have thought that it was insulated all the way to the duct terminus. Is it not?

  10. #23
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Originally posted by travisfl
    Originally posted by nyrfan
    Where the handler comes though in the attic is the 100% not “insulated” attic above the garage, could the gain be happening there on the supply plenum as it’s called?
    Certainly, if the plenum isn't insulated.

    Florida Building code requires that the garage plenums be sheet metal up through the point where they penetrate the wall / ceiling, so I assume yours is? I also would have thought that it was insulated all the way to the duct terminus. Is it not?
    I think you'll find the sheet metal in the code "to be" adopted ,maybe this October.

    The description"garbage bag " sounds like insulated flex.


    Code has been R6 insulation for some time now. Went back to look if the OP mentioned year built,and found it's a "multi staged " heat pump,if it really is two stage,i't gonna run a lot in low,but should be able to maintain at least 78° at around 95°.


    Sounds like some of the duct may be very close to the shingles,temperature there is hotter,may be part of the supply gain in temp..

  11. #24
    Join Date
    Jan 2005
    Posts
    340
    Originally posted by dash
    I think you'll find the sheet metal in the code "to be" adopted ,maybe this October.[/B]
    From the 2003 IRC:

    SECTION R309
    - GARAGES AND CARPORTS
    - - - R309.1.1 Duct penetration. Ducts in the garage and ducts penetrating the walls or ceilings separating the dwelling from the garage shall be constructed of a minimum No. 26 gage (0.48 mm) sheet steel or other approved material and shall have no openings into the garage.

  12. #25
    Join Date
    Apr 2005
    Posts
    83
    Originally posted by dash
    Originally posted by travisfl
    Originally posted by nyrfan
    Where the handler comes though in the attic is the 100% not “insulated” attic above the garage, could the gain be happening there on the supply plenum as it’s called?
    Certainly, if the plenum isn't insulated.

    Florida Building code requires that the garage plenums be sheet metal up through the point where they penetrate the wall / ceiling, so I assume yours is? I also would have thought that it was insulated all the way to the duct terminus. Is it not?
    I think you'll find the sheet metal in the code "to be" adopted ,maybe this October.

    The description"garbage bag " sounds like insulated flex.


    Code has been R6 insulation for some time now. Went back to look if the OP mentioned year built,and found it's a "multi staged " heat pump,if it really is two stage,i't gonna run a lot in low,but should be able to maintain at least 78° at around 95°.


    Sounds like some of the duct may be very close to the shingles,temperature there is hotter,may be part of the supply gain in temp..
    1-House will hold 78 at 95 but can get no lower
    2-The ductwork in a few places are tied to the rafters bringing it closer to the roof shingles and out of the insulation.
    3-Have not climbed up there yet to see if it's marked.

    Felix

  13. #26
    Join Date
    Jan 2005
    Posts
    340
    What is your plenum made out of: steel or duct board. If the former, does it have insulation wrapped around it (or inside it, for that matter)?

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