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  1. #1
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    Humidity seems way too high

    Hi -

    I had a new house built at the end of 2017, so I've been in it 1.5 years. The first winter we noticed a lot of condensation on our windows, so much so that the water would leak down to the floor. We would also have ice on the windows.

    Our builder said that because of the new construction, there may be a lot of water and it would eventually get better after the first winter. They recommended we get a dehumidifier so we did and it helped a little. However, as soon as we switched it off, humidity would go right back up to where it was within an hour or 2. (around 60%)

    Fast forward to this past winter and things did improve a lot but we still had some condensation. I would run my dehumidifier every few days to keep it under control. (hovered around higher 30's to low 40's)

    So here we are this summer and humidity is still pretty high - around 68%. AC temp is set to 73 degrees. So I started running my dehumidifier again and got it down to around 57-60%. Seems like I will have to keep running the dehumidifier every few days to maintain this.

    However is this normal? I live in Ohio if that matters but something seems really off. We have had HVAC professionals look at this but they never got to the bottom of what's going on.

    Can anyone give me some help on what to try or do next?

  2. #2
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    Quote Originally Posted by pidgeynerd View Post
    Hi -

    I had a new house built at the end of 2017, so I've been in it 1.5 years.
    The first winter we noticed a lot of condensation on our windows, so much so that the water would leak down to the floor.
    We would also have ice on the windows.

    Our builder said that because of the new construction, there may be a lot of water and it would eventually get better after the first winter.
    They recommended we get a dehumidifier so we did and it helped a little.
    However, as soon as we switched it off, humidity would go right back up to where it was within an hour or 2. (around 60%)

    Fast forward to this past winter and things did improve a lot but we still had some condensation.
    I would run my dehumidifier every few days to keep it under control. (hovered around higher 30's to low 40's)

    So here we are this summer and humidity is still pretty high - around 68%. AC temp is set to 73 degrees.
    So I started running my dehumidifier again and got it down to around 57-60%.
    Seems like I will have to keep running the dehumidifier every few days to maintain this.

    However is this normal?

    I live in Ohio if that matters but something seems really off.
    We have had HVAC professionals look at this but they never got to the bottom of what's going on.

    Can anyone give me some help on what to try or do next?
    Set t-stat to 76'F

    Set dehumidifier to 54%

    ________________________ Set It + FORGET IT. ~
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  3. #3
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    Thread Starter
    Quote Originally Posted by dan sw fl View Post
    Set t-stat to 76'F

    Set dehumidifier to 54%

    ________________________ Set It + FORGET IT. ~
    76 might be too hot for us but are you basically saying that a dehumidifier should be running non-stop? I was never able to find out if its normal to do that or not. Or if you should run it for a day or 2, then switch it off a day or 2, then repeat.

  4. #4
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    Quote Originally Posted by pidgeynerd View Post
    76 might be too hot for us but are you basically saying that a dehumidifier should be running non-stop? I was never able to find out if its normal to do that or not. Or if you should run it for a day or 2, then switch it off a day or 2, then repeat.
    Dehumidifier should only run when the A/C is idle.

    1/2 The time between 9 pm - 10 am

    A/C needs to provide < 56'F SUPPLY AIR.

    A/C should run ~ 70+% of the time when it's > 84'F outside.
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  5. #5
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    Post # 2 = operating parameters to determine
    How well or poor the equipment performs for a week or so.

    Record R.H. / Tin & Toutside ~ 10 times a day
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  6. #6
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    You say you had HVAC professionals look at you home and they couldn't figure out the reason for the high humidity. i have a hard time believing that a good HVAC company couldn't figure out what is going on. Humidity just doesn't magically appear inside a home, it is either produced by the homeowner or is getting into the home by leakage of moisture vapor or actual water entering.

    What form of ventilation was installed in the home when it was built and how is it controlled? There should be both exhaust and fresh air intake capacities that are either built into the HVAC system(s) itself or stand alone items.
    Use the biggest hammer you like, pounding a square peg into a round hole does not equal a proper fit.

  7. #7
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    Thread Starter
    Quote Originally Posted by dan sw fl View Post
    Dehumidifier should only run when the A/C is idle.

    1/2 The time between 9 pm - 10 am

    A/C needs to provide < 56'F SUPPLY AIR.
    I have a separate portable dehumidifier, but I can set it up on a schedule using a smart switch. My AC comes switches on and off very quickly at these external temps (75-80 degrees).

    How do I measure the supply air? I'm a complete noob when it comes to HVAC.

  8. #8
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    Quote Originally Posted by firecontrol View Post
    You say you had HVAC professionals look at you home and they couldn't figure out the reason for the high humidity. i have a hard time believing that a good HVAC company couldn't figure out what is going on. Humidity just doesn't magically appear inside a home, it is either produced by the homeowner or is getting into the home by leakage of moisture vapor or actual water entering.

    What form of ventilation was installed in the home when it was built and how is it controlled? There should be both exhaust and fresh air intake capacities that are either built into the HVAC system(s) itself or stand alone items.
    I completely agree with you. Here is what I know - I have a dual zone HVAC system and a 5 ton AC, I think the system is single stage. I don't know how to answer the other questions but I can certainly take pictures or get you models numbers etc. if you tell where to find it.

  9. #9
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    Quote Originally Posted by pidgeynerd View Post
    I have a separate portable dehumidifier, but I can set it up on a schedule using a smart switch. My AC comes switches on and off very quickly at these external temps (75-80 degrees).

    How do I measure the supply air? I'm a complete noob when it comes to HVAC.
    Portable dehumidifier should have a dial to set in the MID-50's % RANGE.

    Use second HYGROMETER - AcuRite Model 1083
    to check room conditions

    https://www.amazon.com/AcuRite-Accur...gateway&sr=8-2
    Last edited by dan sw fl; 05-22-2019 at 09:11 PM.
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  10. #10
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    Quote Originally Posted by pidgeynerd View Post
    I completely agree with you. Here is what I know - I have a dual zone HVAC system and a 5 ton AC, I think the system is single stage. I don't know how to answer the other questions but I can certainly take pictures or get you models numbers etc. if you tell where to find it.
    The model #'s are stated on the nameplates for the Air Handler inside and the Condenser outside.

    5-Ton A/C should be used in ~ 5,000+ Square Foot 2017 Built home in Ohio.

    I do NOT Plan to use ANY 5-TON units in the 30,000 sq foot ' Castle ' I am designing.
    _ _ _ Eight+ 3-ton and a few 4-ton A/C units + 6, 7 OR 8 Dehumidifiers may be adequate in South Florida.
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  11. #11
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    Thread Starter
    Quote Originally Posted by dan sw fl View Post
    Portable dehumidifier should have a dial to set in the MID-50's % RANGE.

    Use second HYGROMETER - AcuRite Model 1083
    to check room conditions

    https://www.amazon.com/AcuRite-Accur...gateway&sr=8-2
    I have this exact one and use this across my rooms for measuring. At least I'm doing something right here. I can set it to mid ~50's but was honestly running it at 35 which is the lowest it could go all this time. Is this a bad idea? I thought it would be more effective. Should normal humidity in my house simply be mid 50's or lower? I have never gotten a good answer on this.

    Quote Originally Posted by dan sw fl View Post
    The model #'s are stated on the nameplates for the Air Handler inside and the Condenser outside.

    5-Ton A/C should be used in ~ 5,000+ Square Foot 2017 Built home in Ohio.

    I do NOT Plan to use ANY 5-TON units in the 30,000 sq foot ' Castle ' I am designing.
    _ _ _ Eight+ 3-ton and a few 4-ton A/C units + 6, 7 OR 8 Dehumidifiers may be adequate in South Florida.
    I know where it is, I can get you a picture. Also my house is around 6000 square feet so it seems like the size is okay. Is it normal to run a dehumidifier 24/7? At my old house 10 mins away, I never had the need for one so it's pretty new for me.

  12. #12
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    Thread Starter
    Update----

    I just read that having your fan switched to "on" is actually bad for reducing humidity. I switched it to auto, let's see if that makes a difference.

    Doesn't anyone know if this is a legit problem with on vs auto on the fan?

  13. #13
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    Jun 2003
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    Madison, WI/Cape Coral, FL
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    I would like to go back to the beginning. Most home have excess air infiltration during typical OH winter to the point where the homes are very dry and need humidification.
    As dry outside air passes through the home, the air is humidified by the moisture in the building's materials and leaks out or is exhausted by the exhaust devices in the home. Typical exhaust devices are the kitchen hood, bath fans, clothes drier, and other fans. Wind and stack effect also move additional air through the home.
    Thus many homes become very dry during winter.
    Lucky you, your home is air tight enough that the moisture levels in your home are excessive. Your home is new and may have closed in with excessive moisture in the building materials. The second winter less of a problem. This may suggest summer moisture levels may be or a crawlspace or basement may be adding excess moisture or moisture from the occupants may be the problem.
    When fixing winter moisture problems, the logical fix is increase the fresh air passing through the home to dry the home down to the desired level. In this case you want to stop the condensation on the windows. As you stated, the is even frost on windows. This indicates that the to avoid condensation, you need an indoor dew point of <32^F or you could warm up the glass by not lowering the temperature in your home or not shielding the glass from the warmth of the home. A small amount of frost or condensation is acceptable provided the moisture does not drip on to the frame and sill.
    Health groups suggest that all modern home should have a minimum of a fresh air change in 3-5 hours when occupied at a minimum. Its more cost effective to do this instead of operating a dehumidifier and you will have much better indoor quality by purging the indoor pollutants and renewing your oxygen.
    Calculate the volume of your home and get a mechanical fresh filtered air system to do this. At a minimum operate ventilation enough to fix the moisture problem.
    This wil fix your winter problem, but it is not the end your problems.
    Lets assume you need 100 cfm of filtered dry winter air to purge indoor pollutants and renew oxygen. During the mild calm wind seasons, your home has much less fresh air infiltration. Measuring you type of high quality air tight home shows that it may take 10-15 hours to get a fresh air change during no winds or stack effect. Indoor pollutant levels will be excessive and oxygen levels decline, not good. Most experts and even some codes suggest year around fresh filtered air change in 4-5 air changes when occupied at a minimum. The total cost of conditioning this air during all seasons in you climate is <$300/year.
    This sounds good by there are couple of problems. While fresh air dry takes care the winter moisture problems, fresh air change during the high outdoor dew point weather, raises the indoor moisture content. You already have a summer moisture problem with out adequate fresh air.
    The first thing is your a/c is not setup ideally. During hot days, a correct installed a/c will over-dry the home slightly. This is intentional to provide a room for under dehumidification during times of less than full sensible cooling loads. A/cs must have significant sensible cooling loads to remove moisture or latent load. Most homes need about 2-5 lbs. of moisture removal per hour to maintain <50%RH. An air tight well insulated home has less sensible cooling loads than your old home. A/c runs less plus the a/c contractors tend to over-size the a/c. More part load cycling and less moisture removal.
    Ready, here is the fix. Get your a/c re-setup to max the moisture removal. This requires a cooling coil that is 30^F below the return air temperature. Your a/c tech can do this by adjusting your air flow through the cooling coil dehumidified. During low/no sensible cooling loads and high outdoor dew points, your a/c is unable to remove enough moisture. A fix for this is to add a small whole house dehumidifier connected to your a/c. Units like the Ultra-Aire have been used on premium homes for many years. In addition to maintaining <50%RH when your a/c does not run enough, they have a fresh air filtering and circulation option designed to get you the fresh air needed for purging indoor pollutants and renew oxygen.
    Enough for now. Check some of my past posts and go to:
    Ultra-Aire.com
    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"

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