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  1. #14
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    68,171
    Trucknorris, this is the Ask Our Pro's forum, and only Pro members that have been vetted by the AOPC may post advise here. Please apply to the AOPC today, thank you.

    You can find the rules for posting and qualifications here.

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

  2. #15
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    4,998
    Quote Originally Posted by marcushvac View Post
    The return is 72 discharge 68 (only a 4-F drop?) outside temp 82F.

    about 1300 sq ft 4 second floor bedrooms, 2 BR, hallway, 2 story entryway

    (It seems to cool off fine and may be oversized thus not running long enough to dehumidify - I wonder if I reverse DIP 7 and 8 yielding -15% cfm if that would help)

    I can measure the pressures but was afraid I'd violate the DIY rules.
    Okay, it took a while to find the 16-SEER 2.5-Ton single stage Goodman but here it is: using 85F outdoors; @ 850-CFM; 24,100-Btuh
    70F IDB; 59F-IWB or, 52.47% RH; 19F indoor temp-drop, Not 4F, Coil is NOT cold enough to dehumidify.
    HI PR 279-psig; Lo PR 124-psig; 2.06-KW; 6.3-amps

    If it feels way too humid: @ 1350-CFM 63-IWB 68% RH; 13F temp-drop a lot lower due in large part to increase in humidity latent load; total of 28,000-Btuh.

    There are major problems that need addressing; first get a CFM airflow check & get it down to 1000 or even 850-CFM so it dehumidifies.

  3. #16
    Air handler appears to be set for 1020 CFM.

    I'll knock it down -15% and see how it changes.

    If that is not enough decrease in air flow and assuming for now the charge is proper, would changing the filter to a MERV 13 from a MERV 8 help? My reading through the forums seems to indicate you folks favor the MERV 8. (Unfortunately this system only has provision for 1" filters 16x20)

  4. #17
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,470
    Quote Originally Posted by marcushvac View Post
    Air handler appears to be set for 1020 CFM.

    I'll knock it down -15% and see how it changes.

    If that is not enough decrease in air flow and assuming for now the charge is proper, would changing the filter to a MERV 13 from a MERV 8 help? My reading through the forums seems to indicate you folks favor the MERV 8. (Unfortunately this system only has provision for 1" filters 16x20)
    Using a higher merv filter will slow air flow. Enough????
    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"

  5. #18
    Quote Originally Posted by teddy bear View Post
    Using a higher merv filter will slow air flow. Enough????
    Regards TB
    83 outside.

    I dropped the CFM by 15% using the DIP switches on the control board. Outlet Temp went from 68 down to 59 --
    73 inlet

    Swapped the MERV 8 for MERV 13 Outlet down to 56 - still moving alot of air. We'll give it some time and see how the humidity does.

    My thanks to all those that responded and may continue to respond.

  6. #19
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    4,998
    Quote Originally Posted by marcushvac View Post
    Air handler appears to be set for 1020 CFM.

    I'll knock it down -15% and see how it changes.

    If that is not enough decrease in air flow and assuming for now the charge is proper, would changing the filter to a MERV 13 from a MERV 8 help? My reading through the forums seems to indicate you folks favor the MERV 8. (Unfortunately this system only has provision for 1" filters 16x20)
    Well, if U were using a cheap fiberglass throwaway filter the velocity would be around 665-FPM; when initial velocity, according to manual D, through a clean throwaway filter ought to be 300-FPM.

    If possible, just go to a lower speed setting.

  7. #20
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    4,998
    83 outside.

    I dropped the CFM by 15% using the DIP switches on the control board. Outlet Temp went from 68 down to 59 --
    73 inlet

    Swapped the MERV 8 for MERV 13 Outlet down to 56 - still moving a lot of air. We'll give it some time and see how the humidity does.
    My thanks to all those that responded and may continue to respond.
    Well, U got the temp-drop to 14F; with a high humidity latent load that could be okay; under normal conditions 18 to 19F would be normal.

    However, a 2.5-Ton 16-SEER; 85-F outdoor temp; 1350-CFM; @75-IDB; 67-IWB, about 67% RH; indoor temp-split would only be 13F...you're at 73F RA temp verses 75F; 83 outdoor verses 85F; we don't know what the actual %humidity is.

    With the higher pressure-drop filter; not best option; the drop went to 17F.
    If U get the air flow right; low enough; it should begin to dehumidify.

  8. #21
    Quote Originally Posted by udarrell View Post
    Well, U got the temp-drop to 14F; with a high humidity latent load that could be okay; under normal conditions 18 to 19F would be normal.

    However, a 2.5-Ton 16-SEER; 85-F outdoor temp; 1350-CFM; @75-IDB; 67-IWB, about 67% RH; indoor temp-split would only be 13F...you're at 73F RA temp verses 75F; 83 outdoor verses 85F; we don't know what the actual %humidity is.

    With the higher pressure-drop filter; not best option; the drop went to 17F.
    If U get the air flow right; low enough; it should begin to dehumidify.
    OK it's been a few hours having changed -15% CFM from 1020CFM orig setting and a MERV 13 in place.
    Return temp is 72 as is the room temp, Indoor Humidity reads 63% (First floor is 74 and humidity is 52%) Outdoor temp is 92

  9. #22
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    Raise the thermostat up 1F and set the fan to "ON" for 30 minutes. Humidity should only go up 2-3%RH... and temperature maybe 1F... unless it's pulling in a lot of attic air. IF when running the fan only you can "smell the attic", then that may answer your question.

  10. #23
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,470
    Quote Originally Posted by motoguy128 View Post
    Raise the thermostat up 1F and set the fan to "ON" for 30 minutes. Humidity should only go up 2-3%RH... and temperature maybe 1F... unless it's pulling in a lot of attic air. IF when running the fan only you can "smell the attic", then that may answer your question.
    Consider that there is 1 lb. of moisture per ton of coil retained on the coil at the end of the cooling cycle. The moisture on the coil will evaporate back to the home is 30-45 mins. with the fan "on". 2-3 lbs. of moisture into 1,800 sqft. of space will raise the indoor %RH 8-10%.
    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"

  11. #24

    Cool

    Quote Originally Posted by teddy bear View Post
    Consider that there is 1 lb. of moisture per ton of coil retained on the coil at the end of the cooling cycle. The moisture on the coil will evaporate back to the home is 30-45 mins. with the fan "on". 2-3 lbs. of moisture into 1,800 sqft. of space will raise the indoor %RH 8-10%.
    Regards TB
    Thanks. Not an experiment I care to do.

  12. #25
    So it's been about a week and the humidity is down to 59% temperature outside 85, return 72, outlet 58.

    Looking through the manual, there doesn't appear to be anything else I can do to lower the blower speed. -15% CFM DIP switch setting in place and a 1" MERV 13 from Filtersfast.com

    Any further suggestions would be appreciated. Thanks guys.

  13. #26
    Join Date
    Jul 2009
    Location
    Northeast, Md.
    Posts
    129
    At the moment you have a 4 degree split, and that is a major issue! It's time to call a tech out to your home. Regardless of what you think is going on. The system must work correctly before you can fix the other issues.

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