Results 1 to 6 of 6
  1. #1
    Join Date
    Mar 2020
    Posts
    17
    Post Likes

    HVAC Replacements Aplenty and Humidity Issues in Crawl Space

    So you may have seen my rusted out heat exchanger thread already. If not, know that I have a package unit gas pack/AC for the lower level that needs replaced.

    My home is a 2,225 sqft. 2 story over a crawl space in upstate South Carolina. The interior has a den with a vaulted ceiling with the 2nd floor balcony overlooking the den. Two upstairs bedrooms are at either end of the upstairs balcony and a bonus room over the garage on the other side of one the bedrooms.

    The upstairs heating and air is a split system heat pump that has been unused for the last 3 years. It was expelling refrigerant like Bernie Sanders giving away other peoples money. The tech said it was unfixable pin holes in the coil so we tried a can of the pin hole sealer crap that didn't work.

    Well since my floor plan is pretty open I put a window unit in my bonus room and let the down stairs heating and air cover the 2 bedrooms overlooking the den.

    I have humidity issues in my crawl space so I had a new vapor barrier installed and a fan in one of the foundation vents that runs in the warm months. I imagine I've made my humidity problems worse by not having a functional upstairs cooling system thus running my down stairs unit more than normal and increasing my duct-work sweating????

    So...having said all that...since I'm at the point of replacing both systems with a know humidity issue under the house is their something I need to know or do when looking for replacement systems?

  2. #2
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    9,765
    Post Likes
    What are your expectations? A couple of well setup a/cs and a dehumidifier in the crawlspace well get you a home that and crawlspace with be comfortable during the heat of the day. The crawlspace will be 50%RH if sized right and sealed.
    Evenings of hot days, the home will have marginal humidity control. During calm weather the home will have have marginal levels of VOCs and CO2/oxygen.
    During rainy days the home will get damp as the day of rain continue. You may get by with marginal mold control, dust mites and stale air.
    This is what most people live with. During dry weather, stale but acceptable.
    If you are looking for the ultimate in comfort and indoor air quaulity, hear is a better way.
    Get the best local a/c contractor that is willing to go in a new direction. Closely size the a/cs to match the cooling loaed. After getting the ducts right sizeed and sealed, install the a/c. Couple a right sized whole house dehumidifier with a controlled filtered fresh air ventilation. The return of the dehumidifier is connected to the open part of the home. The dry air supply is connected to the two a/cs and crawlspace.
    The fresh is sized to change the air in the home is 4-5 hours whenever the home is occupied to purge the indoor pollutants and renew oxygen.
    Properly sized/setup a/c will maintain 50%RH while occupied and properly ventilated. During evenings and rainy days, the whole house ventilating dehumidifier will maintain 50% whenever the a/c does run enough. This healthy and comfortable
    Once you get to the comfort and indoor air quality, you will never be able to go back to the haphazard stale air and marginal humidity control.
    It takes top notch contractor and some training to get it perfect.
    If you are not ready for all of this, I understand and disregard my postl
    Interested in your comments.
    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"

  3. Likes kangaroogod, CUfan99 liked this post.
  4. #3
    Join Date
    Mar 2020
    Posts
    17
    Post Likes
    Thread Starter
    I was really hoping I could avoid having to seal and add a dehumidifier to the crawl space. I'm going to be hard pressed financially just to replace both systems.

  5. #4
    Join Date
    Mar 2020
    Posts
    17
    Post Likes
    Thread Starter
    Am I at least on the right track thinking that once I get an operational up-stairs AC going that will reduce my ductwork sweating under the house and thus decrease the humidity? Or is that contribution probably negligible due to the SC humidity?

  6. #5
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    9,765
    Post Likes
    Colder ducts in damp space will have more condensation on the ducts. If you are in a green grass climate, get one good whole house dehumidifier with warm dry air duct to the crawlspace and the entire home. The warm dry air will also warm the cold ducts a which will also reduce the possible sweat problems.
    Seal the crawlspace vents and also consider fresh air ventilation option with the whole house dehumidifier like the Ultra-Aire whole house units.
    The Ultra-Aire units use less electricity to keep the whole house <50%RH than a single less efficient free standing dehumidifier.
    Imagine healthy, comfortable, mold and dust mite home.
    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"

  7. #6
    Join Date
    Oct 2011
    Location
    Culver, Oregon (Central OR)
    Posts
    2,653
    Post Likes
    Good stuff Teddy.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Contracting Business
HPAC Engineering
EC&M
CONTRACTOR