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  1. #14
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,258
    Quote Originally Posted by backpacker View Post
    Awesome posts, everyone! Answers to several questions on the replies are:

    10) Yes, am interested in fresh air supply during calm weather but don't know how to solve that.
    11) Leakage at the unit is always a possibility. But both my supply and return ducts are tight with mastic and good takeoffs.

    Thanks!!!

    Backpacker
    The Santa Fe Advance is a powerful dehu and able to handle 3,500 sqft. of space Get a duct kit for the SF A. The intake comes with a 6" and 10" return. Have your a/c tech bring a 6" fresh air duct in through the rim joist to the 6" return. Connect the 10" return to a duct from the main floor.
    On the supply side, attach a 10" Tee with a damper on the side of the tee open to the crawlspace. Connect a 10" supply duct to the mainfloor. Use insulated flex duct for all of the ducts.
    Partially open the supply to the crawlspace enough to keep the crawlspace 50%RH. Open the 6" fresh air enough to introduce 70-80 cfm of fresh air to the dehumidifier. The fan on the dehu can operate 24/7 to provide circulation and fresh air throughout the space.
    Keep us post on your results.
    Regards TB
    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"

  2. #15
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,708
    6 tons for 3200 sq ft. 533 sq ft per ton. Probably a bit over sized.
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    How many times must one fix something before it is fixed?

  3. #16

    Clarification on upstairs/downstairs; tech coming tomorrow!

    My RH problem is downstairs; upstairs is always much better. Agreed that my upstairs unit is oversized, but it almost always runs on 1st stage cooling only. I assume that is because I set the humidity on the tstat to 45%. The RH upstairs is almost always below 60%; 55% on avg.

    Back to the downstairs unit. Today the unit ran for 18 minutes to drop the temp by 1 ^F. That's probably about what it runs per cycle to maintain as well. The delta temp was 14^F.

    My tech comes tomorrow. Sounds like the order of business is:

    1) Have the tech check refrigerant charge/line per udarrell's list.
    2) Add duct kit and ducts to the SF A dehu per TeddyBear's list.

    Please confirm nobody is recommending to:

    1) Increase the size of the return duct/grille on the package unit. I'm at 20x25 grille, 25 ft of 16" round flex for a 3 ton.
    2) Change the DIP switches on the package unit to reduce airflow down to 1000 or 800 CFM.

    I'll definitely keep everyone posted!

  4. #17
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
    Posts
    4,145
    I think your manual J may have been "faked". When they do a load calculation inputting exaggerated values for air leakage and heat gain to get to that magic "500sqft per ton" result they want. 3.5 tons times 500sqft is 1750. Scary close to the 1800sqft that your downstairs is...

  5. #18
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,708
    Still should have more then a single 20X25 return for a 3 ton.

    Your upstairs unit is doing some of the cooling work for the first floor. Even with slowing the blower on the first floor unit, it will only be able to do so much toward moisture removal.

    The dehumidifier will have to do most of your humidity control.
    Contractor locator map

    How-to-apply-for-Professional

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

  6. #19
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,258
    The important point is that the a/c cooling coil must be <45-50^F when cooling. This maxes the amount the moisture the a/c will remove while doing routine cooling. T-stat setup when the home is unoccupied also provides an extended a/c run on cool down which will remove extra moisture. This minimizes the dehumidification needed by the dehumidifier.
    Keep us posted.
    Regards TB
    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"

  7. #20

    Tech came but nothing new discovered; I discovered floor of package unit is wet

    Quote Originally Posted by teddy bear View Post
    The important point is that the a/c cooling coil must be <45-50^F when cooling.
    I put a wireless thermometer on the bottom right next to my coil drain pan in the unit. The lowest temperature over a 24 hr period is about 57^F. I assume that's probably a few ^F over the actual coil temp??? The hygrometer on the sensor says 99% :-)

    Tech came yesterday and says there are no refrigeration issues whatsoever. He made a small "tweak" to slow down the blower, but it must have been a very small adjustment. He's sending the ductwork fellow to give me a bid on a mixing box and a second return, and hopefully an increase in return duct diameter to 18". He's out of ideas other than that.

    When placing my thermometer in the package unit, I noticed that the floor insulation is wet. No visible water is present, but it's "mushy". This must have been this way ever since my drain pan cracked and was replaced early in the spring. Is this part of my issue? How can I get that fiberglass dried out?

  8. #21
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,258
    Is thermometer in the air stream after the coil or before? You want the air temp after the air flows throught the coil. 57^F is not cold enough. Increasing the return size is going to increase the air flow and decrease the temperature drop. We are looking for 52-55^F air max. Expect the %RH to be extremely high after the blower shuts off and the coil dries.
    Turn the fan "on" mode for a day to dry out the insulation around the coil. If the insulation gets wet, leaky pan or air blowing off the coil may be a problem also.
    Keep us posted.
    Regards TB
    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
    With the cooler weather here the techs are ready to increase the size of my return duct to 18", add a mixing box, and add a second return grill and duct. Some questions about what the different techs offered to do are:

    1) What materials should be used for the return boxes? I've had 3/4" plywood, radiant barrier OSB, sheet metal, and duct board (shiny side in) all recommended by different techs.

    2) I've got a mass of tiny copper pipe on the return side of my coils. It seems to be dripping water on the floor of the unit and some into the return duct sq to rnd adapter. See images below. Should this pipe mass or large pipe above be insulated or somehow modified to eliminate dripping moisture?

    Thanks!
    Backpacker

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  10. #23
    Join Date
    Feb 2009
    Location
    Tallahassee, FL
    Posts
    6,007
    The dripping tubes are a concern. It seems that they do leave the factory this way but your recent repairs have exaggerated the problem.

  11. #24
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,258
    ?Could a drain pan extension position as to catch the moisture and return it to the drain pan. Also bending the tubes to be over the pan extension may make the simpler. Insulating small tubes is a problem. Dont'forget about readjusting the air flow to get a cold coil to remove moisture from the air. For 75^F, 50%RH, you need 45-48^F coil temp.
    Regards TB
    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
    Feb 2009
    Location
    Tallahassee, FL
    Posts
    6,007
    I wonder if the pictured valve is out of adjustment..

    This can also lead to warm coil.

  13. #26
    Join Date
    Jul 2008
    Location
    Rochester NY
    Posts
    4,699
    Quote Originally Posted by beenthere View Post
    6 tons for 3200 sq ft. 533 sq ft per ton. Probably a bit over sized.
    Exterior and interior insulation. Sounds like a well built, insulate house. 1000sf ton would probably be too big.

    Do you leave doors open or closed? Jump ducts? Blower door number? Bedroom to hall delta p when system running?

    The size of your units indicates a LOT of airflow, possibly creating huge pressure imbalances that lead to exacerbated leakage to and from outside.
    Which makes more sense to you?
    CONSERVATION - turning your thermostat back and being uncomfortable. Maybe saving 5-10%
    ENERGY EFFICIENCY - leaving your thermostat where everyone is comfortable. Saving 30-70%

    DO THE NUMBERS! Step on a HOMESCALE.
    What is comfort? Well, it AIN'T just TEMPERATURE!

    Energy Obese? An audit is the next step - go to BPI.org, or RESNET, and find an auditor near you.

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