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  1. #1

    whole home dehumidifier?

    I am new here, and hopefully posting in the correct forum... I am trying to decide if I should have a whole home dehumidifier installed or if there are other options. I wanted to get some opinions before I call my local HVAC and have them try to sell me something if I don't necessarily need it. So I have approximately 1200 sq ft upstairs with about a 800 sq ft unfinished basement. The house has a permanent wood foundation with 2x6 walls with fiberglass insulation. The house is a bi level and the foundation is only about 4 feet underground.. The problem is I have a 220g fish tank with about a total water volume of about 300g. So on any given day it evaporates about 3-5g of water, give or take. The house is sealed very well so I always have condensation on the windows and during this last winter I had moisture between the insulation and the exterior wood of the foundation, and also a lot of condensation around my doors, etc. I want to get rid of the moisture on the foundation walls and I don't want them to rot before I can have a concrete foundation put in. I guess what I am wondering is if a while home dehumidifier is the best option or are there others? I've heard fresh air exchangers are useful. And no, I am not getting rid of the tank. Haha. Any help our advice is greatly appreciated and sorry for the long read.

  2. #2
    Join Date
    Jan 2004
    Location
    PA
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    68,795
    Unless you live in a desert. Fresh air exchanges alone won't help in the summer. So yes a whole house dehumidifier would be the answer.
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  3. #3
    Join Date
    Nov 2004
    Location
    SW FL
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    6,432
    You didn't mention what Dehumidifier you currently have.
    http://www.walmart.com/browse/heatin...ineresult=true
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    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

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  4. #4
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
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    6,645
    Quote Originally Posted by bud217 View Post
    I am new here, and hopefully posting in the correct forum... I am trying to decide if I should have a whole home dehumidifier installed or if there are other options. I wanted to get some opinions before I call my local HVAC and have them try to sell me something if I don't necessarily need it. So I have approximately 1200 sq ft upstairs with about a 800 sq ft unfinished basement. The house has a permanent wood foundation with 2x6 walls with fiberglass insulation. The house is a bi level and the foundation is only about 4 feet underground.. The problem is I have a 220g fish tank with about a total water volume of about 300g. So on any given day it evaporates about 3-5g of water, give or take. The house is sealed very well so I always have condensation on the windows and during this last winter I had moisture between the insulation and the exterior wood of the foundation, and also a lot of condensation around my doors, etc. I want to get rid of the moisture on the foundation walls and I don't want them to rot before I can have a concrete foundation put in. I guess what I am wondering is if a while home dehumidifier is the best option or are there others? I've heard fresh air exchangers are useful. And no, I am not getting rid of the tank. Haha. Any help our advice is greatly appreciated and sorry for the long read.
    3-5 gal. per day is 25-40 lbs/pints plus the moisture from the occupants and fresh air ventilation.
    You need about 100 pint per day whole house dehumidifier. Whole house ventilating dehumidifiers like the high efficiency Ultra-Aire xt105h are ideal for high dehumidification/ventilation needs. What is your climate?
    When the outdoor dew points are below 50^F, the fresh air ventilation will dry the home. Tell us about the climate you live in to help to decide about a HRV for cold weather ventilation pay back.
    Also you a/c needs to be optimized for moisture removal.
    More info....
    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. #5
    Alright thanks so far for the input. I'll try to answer some of the questions. I currently have a stand alone soleus 70 point dehumidifier that will run constantly. I was hoping to find something more energy efficient, if possible. I live in central Wisconsin, so the winters are cold, and like I said this is when I'm having the most condensation. Thanks for the help! If I need to answer any other questions, let me know.

  6. #6
    Join Date
    May 2004
    Location
    south louisiana
    Posts
    3,327
    x 2 ultra aire whole house dehumidifier.
    The cure of the part should not be attempted without the cure of the whole. ~Plato

  7. #7
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
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    6,645
    Quote Originally Posted by bud217 View Post
    Alright thanks so far for the input. I'll try to answer some of the questions. I currently have a stand alone soleus 70 point dehumidifier that will run constantly. I was hoping to find something more energy efficient, if possible. I live in central Wisconsin, so the winters are cold, and like I said this is when I'm having the most condensation. Thanks for the help! If I need to answer any other questions, let me know.
    The Ultra-Air uses 5 amps to remove 105 pints per day. Your uses current unit 6-8 amps to remove 70 pints hopefully. You may reduce operating cost 50% and reduce indoor %RH.
    During the winter, exhausting the area where the fish tank is located would be a minimum approach. I would not use a dehumidifier during cold weather because you need <35^F dew point in the home to avoid condensation on the windows. Cheaper to heat makeup air than operate any dehumidifier during cold weather.
    All of you info indicates you have a air tight home that need some fresh air ventilation during during winter weather. The question is how much. If a supplemental 50 cfm of fresh air 24/7 does the job, a HRV will not have good payback. If you need 150 cfm of supplemental dry winter air that is heated with LP or electricity, the HRV will have a payback.
    Also consider that homes that are air tight during cold windy weather are unhealthy during calm weather with the windows closed. You need an air change in 4-5 hours when the windows are closed and the home is occupied. The whole house ventilating dehu could supply additional fresh air to control winter moisture and provide fresh air and summer dehumidification.
    If we need more clarification, repost.

    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"

  8. #8
    TB, thanks for the help. But I think I need some clarification. Let me see if I understand what you are saying... Instead of running a dehu during the winter I should be bringing in fresh air, and for summer I should be running a dehu? The tank is the centerpiece of my living room, so Im not really sure how I would exhaust it? Last summer I had the tank and didn't have any humidity problems. I run the a/c most of the time because I need to keep the temperature of the tank below 80^f. So my biggest concern is winter time. Also, what do you mean by being unhealthy during calm weather with the windows closed? Are you talking in winter when it is calm? How do I figure out how many cfm of fresh air I need? What equipment do you think I need? And do you have any links to it? Thanks again.

  9. #9
    bump. I would really like it if TB could clarify some of the things on what I posted above. im still kind of scratching my head. Thanks!

  10. #10
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
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    6,645
    Quote Originally Posted by bud217 View Post
    TB, thanks for the help. But I think I need some clarification. Let me see if I understand what you are saying... Instead of running a dehu during the winter I should be bringing in fresh air, and for summer I should be running a dehu? The tank is the centerpiece of my living room, so Im not really sure how I would exhaust it? Last summer I had the tank and didn't have any humidity problems. I run the a/c most of the time because I need to keep the temperature of the tank below 80^f. So my biggest concern is winter time. Also, what do you mean by being unhealthy during calm weather with the windows closed? Are you talking in winter when it is calm? How do I figure out how many cfm of fresh air I need? What equipment do you think I need? And do you have any links to it? Thanks again.
    All homes need an air of fresh air in 4-5 hours. This is about 70 cfm of fresh air. The outdoor dew point is very low during cold weather. Fresh dry air entering the home and moist loaded air leaving removes 3-4 lbs. of moisture per hour. During cold weather, you need a <35^F dew point inside to avoid condensation on the windows. Home dehumidifiers are unable to maintain that low of levels. If you need a little more ventilation than you get naturally, the ventilating dehumidifier will add enough to keep the windows during cold weather.
    As the weather warms, the outdoor dew points rise but the temps of windows rise also. So you are not concerned. But keep in mind your home breathes less during warm calm weather. This is unhealthy because like moisture, indoor pollutants build up and oxygen levels decline. You need the fresh air ventilation whenever the home is occupied and the wind is not blowing. Basement musty and dust mites are the results of +60%RH inside the home during warm weather. Fresh air ventilation adds some moisture to the home when maintain <50%RH. A/c will handle it during significant cooling load and a high efficiency wh house defu will maintain <50%RH when the air is unable. A small whole house dehu like the Ultra-Aire 70 H connected to your a/c will do the job of supplemental fresh and maintaining <50%RH.
    Keep us posted.
    Start by getting a small amount of fresh air and using your dehu.
    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. #11
    Join Date
    Jan 2005
    Location
    Emerald Coast
    Posts
    965
    .

    What temperature are you maintaining during the Winter months?

    Is your tank covered?
    ..
    Do not attempt vast projects with
    half vast experience and ideas.
    ...

  12. #12
    Alright, well right now I open the windows as much as possible to get fresh air in. If you think the ultra aire 70h is a big enough unit and will do what I need it to do, then I will be getting one of them.

    Sleuth - During the winter I have the house set to 70 when Im home, and 62 when Im not. I cant keep the tank covered as it doesn't allow for proper air exchange.

    Once again, thanks for all the help.

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