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  1. #14
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    Apr 2007
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    Tucson, Arizona
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    Did you watch as they applied the mastic? Did they remove the shiny vapor barrier and seal the physical duct inside, or just the outer jacket that's visible in the pictures? I could understand how that could lead to more problems, I live in a dry climate, but could see how things could get worse if the duct itself (inner core) wasn't sealed well. I could be way off, so don't think to much of it, Teddy Bear is the resident humidity expert.
    There are two ways to do things, Right and Again.

  2. #15
    Join Date
    Jul 2016
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    Quote Originally Posted by shavedneon View Post
    Did you watch as they applied the mastic? Did they remove the shiny vapor barrier and seal the physical duct inside, or just the outer jacket that's visible in the pictures? I could understand how that could lead to more problems, I live in a dry climate, but could see how things could get worse if the duct itself (inner core) wasn't sealed well. I could be way off, so don't think to much of it, Teddy Bear is the resident humidity expert.
    Yes I watched... He pulled back the shiny part and insulation. He the took off the corrugated flex line exposing the collar. He placedar mastic around the collar, placed the flex line back on (zip tied it). Then he placed the insulation and shiny back over the corrugated line (zip tied that) then put a lot of mastic around all of that. I went up to the attic yesterday and it was still not dry and I felt some condensation at the bottom part of the duct.

  3. #16
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
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    Slowing blower speed always removes more moisture from the air and causes more condensation on the air handling equipment exposed to high dew point air. A 30^F split is ideal for 50%RH during high cooling loads. 75^F, 50%RH, a 55^F dew point requires a 45^F coil temperature. Then look for condensation and re-insulate the spots that have condensation with a closed cell foam tape like Rubetex.
    This will get you 50%RH on a hot day. Get a small whole dehumidifier like the Ultra-Aire for 50%RH during low/no cooling loads and high outdoor dew points.
    Regards Teddy Bear
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

  4. #17
    Join Date
    Jul 2016
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    Thread Starter
    Quote Originally Posted by teddy bear View Post
    Slowing blower speed always removes more moisture from the air and causes more condensation on the air handling equipment exposed to high dew point air. A 30^F split is ideal for 50%RH during high cooling loads. 75^F, 50%RH, a 55^F dew point requires a 45^F coil temperature. Then look for condensation and re-insulate the spots that have condensation with a closed cell foam tape like Rubetex.
    This will get you 50%RH on a hot day. Get a small whole dehumidifier like the Ultra-Aire for 50%RH during low/no cooling loads and high outdoor dew points.
    Regards Teddy Bear

    Sounds like a plan Teddy... I will do that. I will slow the blower down to MED and monitor the humidity. I will also watch for any extra condensation on the air handling equipment.

    I know that my plenum is insulated on the inside and has mastic all on the outside. But where the supply air goes out into the ducts, that part has no insulation, just the sheet metal it's made out of. The ducts off of the supply has tape and mastic. I know you say lowering the blower speed I'd be dealing w/ more condensation so would wrapping the supply air up in some Reflectix work?

    Also, I'm having trouble finding some of that closed cell foam tape at the big box stores. I'm just finding thin strips, and I would imagine I need something a little thicker. I'll check some HVAC spots in my area.
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  5. #18
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    Jun 2003
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    Madison, WI/Cape Coral, FL
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    Quote Originally Posted by MSanchez214 View Post
    Sounds like a plan Teddy... I will do that. I will slow the blower down to MED and monitor the The ducts off of the supply has tape and mastic. I know you say lowering the blower speed I'd be dealing w/ more condensation so would wrapping the supply air up in some Reflectix work?

    Also, I'm having trouble finding some of that closed cell foam tape at the big box stores. I'm just finding thin strips, and I would imagine I need something a little thicker. I'll check some HVAC spots in my area.
    Taping bubble wrap with air tight tape will reduce condensation. Try it on a wet spot.
    Keep us posted. Report supply/return temp/%RH with speed change.
    Watch space %RH rise during evenings and wet cool days with high outdoor dew points.
    Regards Teddy Bear
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

  6. #19
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    Jul 2016
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    Quote Originally Posted by teddy bear View Post
    Taping bubble wrap with air tight tape will reduce condensation. Try it on a wet spot.
    Keep us posted. Report supply/return temp/%RH with speed change.
    Watch space %RH rise during evenings and wet cool days with high outdoor dew points.
    Regards Teddy Bear
    I will do that, Teddy.

    I have this IR gun (pic attached) I will use at the return and supply to measure temps w/ current blower conditions and I'll measure current outdoor conditions.
    Then I will make the blower speed adjustment, let it run a while and do the same and report back to you.

    Blower is currently set on MED HI and I will make adjustment to MED. I'll also be checking for condensation as you said!

    Thank you so much...
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  7. #20
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    Jul 2016
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    Ok... Here's an update guys! Might be a lengthy one so I'm sorry.
    My blower has 4 speeds HIGH, MED, MED LOW, and LOW. (I was mistaken earlier sorry).
    All readings were taken inside Master Bedroom from same supply and return.
    When reading temps on supply/return, I used 3 different thermometers to measure temperature and took the average.

    Blowers set on MED speed. Thermostat set at 76°
    Outdoor Temp/Humidity = 92°/54%
    AcuRite Digital Monitor shows = 73°/57%
    Return Air = 74.9°
    Supply Air = 60.6°
    Difference of 14.3°

    Changed blower to MED LOW speed. Thermostat got up to 79° before A/C started.
    Outdoor Temp/Humidity = 91°/56%
    I let the A/C run for 30 minutes straight (set thermostat down to 74°) After 30 minutes thermostat showed 75°
    AcuRite Digital Temp/Humidity = 73°/56%
    Return Air = 74.3°
    Supply Air = 58.5°
    Difference of 15.8°

    I was REALLY hoping lowering the blower speed, I would see a bigger difference. I already took it down from HIGH, to MED. Then I tried MED LOW and it only dropped it
    1°. So I moved it back to MED and I'll await suggestions.

    And as far as condensation goes, none was on top but I did notice a little bit at the bottom of the handler (see pics), but again, that was only after 30 minutes of run time at the lower speed.

    Thank you all in advance for your patience and advice...
    Attached Images Attached Images   

  8. #21
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    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
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    Why not stay on Med Low. Let it run for a few days. It takes time to drop the %RH because of moisture in the materials inside the home.
    Tape on insulation on any of the sweating ducts.
    Keep us posted.
    Regards Teddy Bear
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

  9. #22
    Join Date
    Jul 2016
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    Thread Starter
    Quote Originally Posted by teddy bear View Post
    Why not stay on Med Low. Let it run for a few days. It takes time to drop the %RH because of moisture in the materials inside the home.
    Tape on insulation on any of the sweating ducts.
    Keep us posted.
    Regards Teddy Bear
    Ok Teddy.... I will move both blowers to MED LOW and monitor them.

    And by tape on insulation on sweating ducts, what does that mean exactly? Should I not concern myself with the condensation seen on the bottom falling into the drain pan?
    Last edited by MSanchez214; 09-02-2016 at 09:28 PM. Reason: Typo

  10. #23
    Join Date
    Sep 2002
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    Any harm in running the indoor coil temperature at 33-34º do you think?

    PHM
    --------

    Quote Originally Posted by teddy bear View Post
    Slowing blower speed always removes more moisture from the air and causes more condensation on the air handling equipment exposed to high dew point air. A 30^F split is ideal for 50%RH during high cooling loads. 75^F, 50%RH, a 55^F dew point requires a 45^F coil temperature. Then look for condensation and re-insulate the spots that have condensation with a closed cell foam tape like Rubetex.
    This will get you 50%RH on a hot day. Get a small whole dehumidifier like the Ultra-Aire for 50%RH during low/no cooling loads and high outdoor dew points.
    Regards Teddy Bear
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  11. #24
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
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    Add insulation to the condensing areas. Try the bubble type with tape on the outer edges to form an air seal to keep damp air from getting into space between the insulation and the duct. Rubitex is a brand of closed cell foam rubber that would be better than the bubble type. Falling into the drain pan? I would insulate any cold area.
    Keep us posted.
    Regards Teddy Bear.
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

  12. #25
    Join Date
    Dec 2002
    Location
    Houston,Texas
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    Sorry if I missed if this was mentioned, but has anyone let him know that by lowering the fan speed to help with the latent levels, will also decrease the amount of sensible heat removed?
    __________________________________________________ _______________________
    “Experience is a hard teacher because she gives the test first, the lesson afterwards" ~ Vernon Law

    "When the teachers become unteachable we're all in trouble"

    "It's what you learn after you know it all that counts." ~ John Wooden



  13. #26
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    Jul 2016
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    Thread Starter
    Ok everybody... Here's an update.

    I have moved both blowers to the MED speed and have a noticed a slight drop in humidity. I am now around the 55-60% range. (I have never seen 55% before this). As far as condensation on the unit, I don't have much except for the little at the bottom of the unit which drips into the drain pan (which I still plan on insulating). I do have one duct that I can't seem to stop it from condensing. I have some GREAT STUFF Window and Door w/ the Great Stuff gun as well. Can I just put this all around the duct work and see what happens? Thanks for any advice once again, guys!!!!

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