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Issues with whole home dehumidification

5 years ago

Total sq ft-2770

Main level-1640 sq ft

Finished walkout basement-1131 sq ft

Open stair case between basement and main level-no door

Have 2 Trane heat pumps and 2 Trane air handlers controlled by separate Nest thermostats.


We have never had crazy high levels of humidity in the house. Usually range from 47% to 54% in the summer. Dry in the winter. Only a few times over the 3 1/2 years we have lived here have I seen it go up to 58% which was in the spring where neither the AC or heat was running and it was very muggy outside. It only remained at that for part of the day but then went down.


We recently had a whole home dehumidifier installed (Honeywell DR65A3000). It was installed on the air handler for our walk out basement. It was first installed without a dedicated return. Dehumidifier was set for 45%. We waited for several days and it never brought the humidity down to 45%. One day it went to 47% but that day the outside humidity and dew point were lower. AC is set at 68/69 during the day and 67 at night. Humidity levels in the basement remained anywhere from 49-54%. Hvac guy came back yesterday and they installed a direct return and felt confident this would solve the problem. It didn't do anything. At midnight AC set at 67 the humidity was 50%. At 6am-52%. At 10:00 this morning the AC was set at 69 and the humidity level was 50% and currently remains there.


It seems like the dehumidifier is doing nothing. That even if we turned it off we would see these same humidity readings. I know it's actually running because I can hear it. It just runs and runs.


Any ideas? Is the dehumidifier too small or is it not even working?


Here's the set up currently:


Direct return comes into the dehumidifier. Then there's ducting that comes out and goes into the bottom of the air handler adjacent to where the regular return is.





Comments (8)

  • 5 years ago

    klem I'm not sure what you are saying. If the AC was doing a good enough job at removing humidity then we wouldn't need a dehumidifier. The dehumidifier has it's own return and then the air passes through the dehumidifier and into the air handler. The dehumidifier drains through the same line that drains the AC. You can see the white piping coming off the dehumidifier in the second picture. This drain line dischargers outside the back of the house.


    We may try turning the dehumidifier off at some point to see what happens with the humidity.

  • 5 years ago

    More people seem disappointed with these than are pleased. Go here and scroll down to read what customers say.

    The subject has several technical aspects I'm not sure I can explain so that you understand (or even need to understand since it's up to your installer to make it work without outside help). I heard you the fist time about it being ducted to air handler but I needed to know which end when I asked " Is the dh proccessing air on discharge side or intake side of ac?"

  • PRO
    5 years ago
    last modified: 5 years ago

    Dehumidification is a complicated subject for a variety of reasons.

    How dehumidification gets inside a structure may be partly due to the occupants of that structure what they are doing. Air conditioning when running provides "some" dehumidification.

    Air conditioning can also reintroduce humidity back into the house at or around the off cycle of the equipment.

    Large household doing lots of laundry daily, a broken dryer vent near an air return. A plumbing leak. Water evaporates, becomes humidity. Infiltration: a new pool was installed. The house under a negative pressure, draws humidity off the pool right into the house. (What is a guess worth?)

    Dehumidification thresholds & dehumidifers what is removed is measured in pints. Pints of moisture. Your particular dehumidifier is rated for 65 pints of removal. We've never had this problem before, so let's just go with the cheapest option. 65 pints is an "entry level" capacity amount. Prices go up from there.

    How is the dehumidifier controlled? is it controlled via humidistat or what?

    Investigation: you never had this problem before, but you don't investigate where this humidity is coming from. Why? (or did you? You didn't say, I go by what you say.)

    Gadgets are a billion dollar industry for this very reason. Let's throw a gadget at a problem. It would be very difficult to get sizing right on a dehumdifier for all the reasons I've listed in this post. They make dehumidifiers with double the capacity yours currently has. I guess beyond that you just keep adding additional units until you make a dent in the humidity levels you have in the house. Either that you investigate find / determine what, when, where how this humidity is potentially coming from.

  • 5 years ago

    Austin air. We have always had this humidity problem. I finally decided to do something about it. We don’t do laundry daily, no new pool, no plumbing leaks, no broken dryer vents. We have bath fans that are used after showering. Our land is properly graded to take water away from the house. Our gutters are good and are piped to shed water far from the house.


    I am sure if other people lived in this house they would not even notice anything with humidity. The older I have gotten the more sensitive to it I have become. I don’t know if you are male or female. Older females will understand what I mean when I say we have our personal summers and I am pretty sure this plays into my sensitivity to humidity. I never measuered humiidity levels in previous houses we lived in. This is the first house I have actually measured the levels in.


    We do not have any mold or musty smells. From everything I have read it is best to keep humidity levels between 40-50%. We have many days where we are in that range. Other days we creep up a bit over that. I am the one that notices this. I will go and lower the thermostat to bring the humidity down for my comfort but then others are too cold. Then we have the occasional day usually in the spring where it feels down right gross for all of us. The humidity is up at 56-58% because it is not warm enough for the AC.


    The dehumidifier is controlled by a Nest thermostat. Yes I realize the dehumidifer is 65 pint. I am not an HVAC professional. That is why I pay for a professional and can only go by what they tell me. I try to read and understand as best I can.


    Are you telling me that any house that has humidity higher than 50% must have problems? You say that there’s many things that factor into it and I understand that. We have a walkout basement. Im sure that factors into it, Our main level is a log cabin. I am sure that factors into it as well. It gets sticky outside here. Current dew point is 64 which is not exactly comfortable. These are things we can not change.


    All I want is to have humidity levels around 45% and no higher than 50% on a daily basis. I will work with the HVAC guy we hired but I am trying to educate myself which helps me better communicate with the professional.






  • PRO
    5 years ago

    Are you telling me that any house that has humidity higher than 50% must have problems?



    No, I live in a high humid climate. Katy, Texas area. Humidity is complicated subject. It varies independently of temperature. A comfort problem is only a problem when you notice it, you posted for that reason right?


    Bath fans? so someone likes steamy showers? Remember humidity can also be a cause due to activity in the home. Just as much as it could be related to infiltration if you are in a humid climate. (You wouldn't need bath fans if you start taking cold showers. So you get where I am going / coming from.) Cause and effect.


    Have you determined the dehumidifier is even running and how often? running all the time, never shuts off. What would that tell you? Is it working right? Is it a capacity issue? what? guessing games lead to more guessing games.


    A lack of humidity will generate problems too... but these are relegated to desert / arid type climates. (Male or Female doesn't matter, high humidity effects all. I do this for a living.)


    Some climates, some homes within those climates may not achieve 50% humidity levels. Infiltration, activities in the home, the design of the HVAC system, equipment chosen etc all contribute or detract from the humidity equation.


    Humidity levels can vary from one room to another. By the time this reaches the sensing mechinism of the nest to turn the dehumidifier on you probably already feel it. The nest is known for problems. The more it is used to control, often times the worse it is. For that reason I discourage it's use.


    The reason I brought up the capacity issue is that your dehumidifier *may be* doing all it can do. There is a limit.


    I've solved humidity issues. It didn't involve dehumidifier or nest thermostat. I am well aware of the *humidity problem*.


    Here's a video partly related to this subject, I also discuss briefly the cons of using dehumidifiers.

    Realize this video subject is geared for a "High Humid Climate". Comfort is a personal decision.







    I service the Katy, Texas area.



    vinmarks thanked Austin Air Companie
  • 5 years ago

    The dehumidifier never turns off because the set point is never reached. The point of my post was to see what the problem could be as far as the dehumidifier never reaching the 45% set point. I know it could be that we need a higher capacity dehumidifier but are there other factors to look at as well? Is the installation correct?


    The humidity levels in our home coincide with what is going on outside. If it's not real humid outside in the summer then inside is ok and the AC can keep humidity in check. When it is spring time and the temps outside aren't high and there's no AC running if it is rainy and muggy then the humidity inside gets high. In the winter we have the opposite. The humidity is lower than I would like. We handle this with a stand alone unit.


    If you don't like Nest what would you recommend?



  • PRO
    5 years ago

    The dehumidifier never turns off because the set point is never reached. The point of my post was to see what the problem could be as far as the dehumidifier never reaching the 45% set point. I know it could be that we need a higher capacity dehumidifier but are there other factors to look at as well? Is the installation correct?


    The humidity levels in our home coincide with what is going on outside. If it's not real humid outside in the summer then inside is ok and the AC can keep humidity in check.


    Humidity in the home is a combination of infiltration & activities in the home. If the home is a recent build, it is more common for it to be activities in the home. Think tight builds. If it's hard for humidity to get in, it's also hard for humidity to get out. Air conditioning primary purpose is to lower temp. You get some dehumidification from that. The more the air conditioning runs the better this will work.


    Tighter builds are often fitted with fresh air, via HVAC system. So infiltration is possible to effect a more recent build.


    Humidity for my climate, if you achieve 50% RH inside consider it good. This doesn't mean you won't hit 40% occasionally. Some may not like the way I say this.


    I don't measure my humidity at my home. I can sense it after being outdoors mowing the lawn or something for an hour or so. Much of what I do in the comfort realm is a feeling.


    You can sense (if you pay attention to it) the dampness or heaviness in the air. If you're outside and it's high humid, what difference does a number make? Other than to tell you what or how much it is.


    Temperature is much different. -- We occasionally get lower humidity outside here, not for very long just enough for you to notice is. The air is crisp, light weight, easy to breathe etc.


    So you can sense the humidity drop, if you walk outside stay outside for an hour or so and come back inside. If you don't notice the difference from outside to inside? Much more likely a problem exists.


    Can I tell what the RH% is in my home? If it's humid outside, I notice the difference coming in I know what I have is doing it's job. I'm not going to get excited over 10% RH difference here and there unless? Remember it's a feeling. Feeling muggy or clammy is the description.


    So if you want better control of humidity. A dehumidifier is it. (notice I said "control") Better control would include a separate control called a humidstat. I would suggest placement in a "known" problem area within the home. Like outside a heavily used bathroom, laundry room area etc.


    Capacity or amount of pints of removal you need is primarily a guessing game in my opinion. Obviously the larger the home probably best to go with larger unit. The more HVAC systems you have, you may need additional dehumidifiers.


    The reason why inverters are the better way forward is that it's not uncommon for HVAC operation to reintroduce humidity back into the home. Because of the natural way an inverter works, renders this potential much less. I haven't had an issue yet in which I (me personally) installed an inverter and had someone still complaining of humidity issues once the operator understands the challenge better. (This was part of the video if you didn't watch all the way thru.)


    Those that don't even realize RH is the problem it is... crickets after inverter ac install.


    Meaning: I tell you up front, that the inverter doesn't "control" humidity. Can you physically tell the difference of 40% RH to 50% RH without the aid of a humidistat telling you what it is? Reason I say this is it's in the desired range.


    The other undiscussed elephant in the room is cost? dehumidifier is cheaper up front, but maintenance, operational cost etc. never go away. What's worse is this was installed and you believe you still have a problem. Based on: a feeling. Am I right?


    The inverter option + proper operation in my climate: you will feel it. (the difference).


    I service the Katy, Texas area.

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