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  1. #1
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    Jun 2016
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    North Texas Indoor Humidity Problems

    I purchased a new to me/used home in Ellis County, Texas. The home was built in 2007 and had one owner. The owner did not disclose the problems they had with the AC.

    There is a 2 Ton Lennox 13HPD0030-230-01 outside and a Goodman ARUF30B14AB in the attic, and a Honeywell RTH6580WF thermostat, heated sq ft is 1194, the attic (including the garage) is filled with 12-14 inches of insulation and it is floored throughout, the garage door is also insulated and it is NE facing, the house has gutters around and they are all draining a good ways from the foundation, there are soffit vents on the east and south only, there is an automatic attic fan on the front kind of large (faces NE) and some other vents that are square on the SE side, the back windows are sunscreened and after 5pm the evening sun is blocked by a large tree that is not evergreen, three interior exhaust fans vent into the attic (bathrooms and laundry), and the kitchen exhaust vents into the kitchen not outside. Behind the house (fenced yard) is a run-off area/field and a stock pond is about 150 yards away that the run-off feeds into. I have one 20x20 return and 15 3-way supplies. I have laminate and ceramic throughout.

    What I'm experiencing:
    I noticed that air seemed cold but not comfortable. I put in my Accurite weather station up to monitor humidity and have moved it from room to room to monitor air temp and humdity. In the kitchen with the thermostat is set at 71F it can read 75F with a humidty of 48% around 7am rising to 62% and a temp of 807F when I have the ac set on 75F. That's before cooking. I usually turn on the laundry room fan when I cook but it doesn't do much. The back bedrooms fluctuate also to 52% humidity during the day only going down to 45% overnight. I've been told that my return air and supply are not equal and need a second return and different supply covers. I've been told that the AC is a dehumdifier and that even if I add a return my humidity may or may not change. I've been told I don't need a whole home dehumdifier. I've been told that nothing is wrong with my AC that it's fine and I need a whole home dehumidifier. I've been told by one company I have a wastewater problem and water is leaking but my water bill was $20.00 for thirty days and my meter is not churning away with no water on (I think the city would have noticed a waste leak, so my plumber said). I have a chronic respiratory problem and my air is so uncomfortable and the humidity I'm accustomed to is between 30-35% but not one person will hear me and not one company services this area with dehumidifiers and or purifiers out the 17 on various dealer sites. I'm so confused. I have mini-humidity catchers around and they stay full of water and my Eva-Dry things need to be recharged every 3-5 days. It has nothing to do with all the rain, the humidity has done this since week two of move-in, I'm now at week seven. Outside humidity does not affect the indoor humidity. I'm cold but it's on 71, it's damp, and it stinks.

    I found paperwork the owner left behind in a closet with the following:
    8-2010 - A fan blade with a 20 degree pitch was replaced along with a hub. Noted on this date that the fan motor blade was leaking oil and may cause issues in the future.
    7-2011 The following capacitors were replaced - CR5 and CR45 on the Lennox and the compressor was water cooled.
    2014 - the Lennox Air Handler was replaced due to "rusting" with the Goodman.

    Since I've been here:
    5-2016 - A local dealer added 1lb of freon, changed an "capacitor that was a 2 stage" to what was single stage, advised there was not a check valve on the pan, and the air handler was rusting, either a new system or add a return. This person found the handler running on low speed, cranked it to high speed.
    5-2016 - HWA sent a person that added another 1lb of freon, added a new cap onto the freon thing that had an o-ring as he said that it making it leak, and that my ac was fine and air handlers don't rust. Found my Honeywell AC filter expanded and damp. The service company felt the humidity.
    6-2016 - Have a water leak it's not an ac problem. Don't install dehumidifiers, not the speciality.

    Any ideas, please. I'd rather be out in the rain on my back porch.

  2. #2
    Join Date
    Nov 2003
    Location
    Pompano Beach
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    Your first issue is you have a mismatched system, so who knows what your getting with capacity and efficiency. Goodman does not engineer their equipment to work with lennox and same goes for lennox with goodman. As far as humidity issues, is the home tight? is the build tight? Have a fire place? Have a licensed professional to come by and do a heat load calc? At this point, you have had 2 lbs of freon installed into the system, why? what was the outside temp when they came out? is the evaporator coil clean? Maybe the fan blade is the wrong pitch and not moving enough air through the condenser coil? Try calling on some neighbors or co workers and see if you can identify a good licensed ac contractor to come out and help you. I see that there has been some gold digging going on.

  3. #3
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
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    Shut off the attic fan for a week and keep measuring your rooms. See if you notice any difference in humidity levels.
    Psychrometrics: the very foundation of HVAC. A comfort troubleshooter's best friend.

  4. #4
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
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    This gets confusing for all. 50-55%RH is a good humidity for most. Keeping a home below 75^F while the outdoor dew points at near 75^F is risking because of possible condensation in the walls and attic ceiling. Also condensation occurs on the outside of the ducts and equipment grows mold.
    Raise the stat to 75^F and monitor the %RH. If below 55%RH most of the time, relax.
    The other part of indoor air quality is a fresh air change in 4-5 hours. When your home is exposed to a 7-10 mile per hour wind, you probably get the fresh air change. Ducts on most a/c leak enough to get this much air during long runs.
    During wet cool weather is when the %RH can get to high. Monitor with your %RH meter to get a feel.
    Keep us posted on the effect of raising the temp to 75^F. Keeping the home warmer and dry is much better than over cooling. This reduces sweating or condensation. Biggest concern is maintain 50%RH.
    Evenings may be problem.
    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"

  5. #5
    Join Date
    Jun 2016
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    Thread Starter

    On raising the temperature

    Quote Originally Posted by teddy bear View Post
    This gets confusing for all. 50-55%RH is a good humidity for most. Keeping a home below 75^F while the outdoor dew points at near 75^F is risking because of possible condensation in the walls and attic ceiling. Also condensation occurs on the outside of the ducts and equipment grows mold.
    Raise the stat to 75^F and monitor the %RH. If below 55%RH most of the time, relax.
    The other part of indoor air quality is a fresh air change in 4-5 hours. When your home is exposed to a 7-10 mile per hour wind, you probably get the fresh air change. Ducts on most a/c leak enough to get this much air during long runs.
    During wet cool weather is when the %RH can get to high. Monitor with your %RH meter to get a feel.
    Keep us posted on the effect of raising the temp to 75^F. Keeping the home warmer and dry is much better than over cooling. This reduces sweating or condensation. Biggest concern is maintain 50%RH.
    Evenings may be problem.
    Keep us posted.
    Regards Teddy Bear
    TeddyBear

    I have done that in the past weeks and when the temp is over 75F, the humidity shoots up over 60% and the outside temp/humidity did not mater. It shoots up to 60% and over on the few days when the outdoor humidity was 50% and on 90% days. Thank you for responding. My Medical Doctor that treats my asthma and immune problems advised me to keep the house at 35%. It is hard to breathe inside the home at 45%. When I lived in MD, I had to have an Infinity System installed in an older home. I cannot relax. The warmer my house gets, the more humid it gets - which is odd to me.

  6. #6
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    Jun 2016
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    Thread Starter
    I will give that a try this morning. Thank you @ShopHound.

  7. #7
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    Jun 2016
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    Thread Starter
    Quote Originally Posted by czkidd View Post
    Your first issue is you have a mismatched system, so who knows what your getting with capacity and efficiency. Goodman does not engineer their equipment to work with lennox and same goes for lennox with goodman. As far as humidity issues, is the home tight? is the build tight? Have a fire place? Have a licensed professional to come by and do a heat load calc? At this point, you have had 2 lbs of freon installed into the system, why? what was the outside temp when they came out? is the evaporator coil clean? Maybe the fan blade is the wrong pitch and not moving enough air through the condenser coil? Try calling on some neighbors or co workers and see if you can identify a good licensed ac contractor to come out and help you. I see that there has been some gold digging going on.
    I have had four contractors, one was a company that had previously serviced and installed the Goodman - replacing the Lennox. He told me that system was not mismatched. Two other contractors told me they were mismatched. I agree they are. The home is tightly built, there is no fireplace. When they put in the freon the first day the temp in the low 70's and 45% humidity outside. The second day the temp was in the mid 80's with 87% humidity outside. I asked the last guy about the fan blade pitch and he stated that the pitch was correct. One contractor told me that there wasn't enough air blowing so he moved the fan speed to high. The last guy that came out told me that it would be best to move the fan speed to low and make the system work longer to remove more humidity. I advised him that there was a bit more humidity on low speed. They all look at me like I'm crazy and retarded. Yes, gold digging is rampant in these parts. There are no Aprilaire Certified dealers that will come to my County due to the miles traveled - closest is 34 miles away. Stops per day, money in the pocket.

  8. #8
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    Thread Starter
    Quote Originally Posted by Shophound View Post
    Shut off the attic fan for a week and keep measuring your rooms. See if you notice any difference in humidity levels.
    I'm going to give that a try today. The last contractor told me that I needed more fan vents in the attic on the SW side of the house. Thanks.

  9. #9
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    Jun 2003
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    Madison, WI/Cape Coral, FL
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    Quote Originally Posted by RTWax View Post
    TeddyBear

    I have done that in the past weeks and when the temp is over 75F, the humidity shoots up over 60% and the outside temp/humidity did not mater. It shoots up to 60% and over on the few days when the outdoor humidity was 50% and on 90% days. Thank you for responding. My Medical Doctor that treats my asthma and immune problems advised me to keep the house at 35%. It is hard to breathe inside the home at 45%. When I lived in MD, I had to have an Infinity System installed in an older home. I cannot relax. The warmer my house gets, the more humid it gets - which is odd to me.
    Outdoor %RH has nothing to do with the amount of moisture in the outside air. It is only a description of the % of capacity of moisture at the current temperature. The dew point or grains per lb. of air are meanful measure of the amount of moisture in the air.
    Early morning the outside air is 80-90%RH and there is dew on the grass. The grass blades are condensing moisture, thus 100%RH. If the temperature is 70^F, 90%RH, the dew point is 68^F. By mid afternoon the temperature is 90^F, 50%RH, the dew point is still 70^F. Any surface below 68^F will have condensation. The amount of moisture in the air is same as early morning. Inside your home if 75^F, 50%RH, 55^F dew point, the a/c removed enough moisture to lower the indoor dew point 15^F.

    On a hot day, your a/c should be able to maintain 75^F, 50%RH, 55^F dew point. If not the a/c does not have a cold enough coil temperature or you have excessive fresh air leaking into your. home. A cold coil a/c removes 3 lbs. of moisture per ton of capacity per hour of steady run. 2 ton operating steady removes 6 lbs. or almost a gallon of moisture per hour, should keep your home dry unless you have excess air leakage.

    When the sun goes down or on a rainy day, the a/c is on/off and will not remove much moisture. If the outdoor dew point is still 70^F, the moisture load is the same as a hot day, but no a/c operation. Not rocket science, the moisture level in the home will be high. This where the dehumidifier is a must. Try to explain this to your tech. Some get, some don't.
    Hot dry weather with plenty of a/c operation will not need a dehumidifier. Wet cool weather, rain, all need supplemental dehumidification with a Dehumidifier. That is if you want to control the indoor %RH. Your home is better off being +75^F, <50%RH than much cooler. If you really want <40%RH at 75^F, you will need an a/c with <40^F coiling coil and larger whole house dehumidifier. Suggest a unit like the Ultra-Aire XT105H mated to cold coil a/c. I would also suggest filtered fresh air ventilation option.
    Or move farther west like the Arizona/NM.
    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"

  10. #10
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    Jun 2003
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    Madison, WI/Cape Coral, FL
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    This is a TX house with a normal a/c and dehumidifier on a wet day.
    TX data.pdf


    Hope this helps.
    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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