Installing a whole house humidifier

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Old 05-09-13, 12:02 PM
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Installing a whole house humidifier

I would like to install a whole house humidifier and humidistat in heat pump system in Florida for medical reasons. Can anyone tell me if this is feasible and if it is, what does it entail......thanks in advance, buzcar
 
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Old 05-09-13, 12:09 PM
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Hi Buz, just curious, but how much higher do you need than what Florida normally provides? In my northern heating dominated climate I'm used to people adding humidity, but I always assumed you folks have plenty to spare.

Now, oversizing a heat pump will cause it to run in short cycles. Following that logic, if you reduce the heat gain, your current system will become oversized. Running in short bursts usually results in not removing enough humidity which would be in the direction you want. Getting that level under control, well I'll leave that to the ac heat pump guys.

Bud
 
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Old 05-09-13, 01:21 PM
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In an effort to satisfy your curiosity Bud, either the heat or A/C is on most of the year in Central Florida so the air in the house gets very dry.

Since I have little to no knowledge of heat pumps because I originally lived in New England, I readily admit that the information you supplied was completely foreign to me. I know that a humidifier can be added to a forced hot air system but I don't know how that can be done on a heat pump with an air exchanger.
 
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Old 05-09-13, 02:12 PM
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I am also in Central Florida. Since I have a humidity setting on my thermostat, I keep mine set at 60%. It now is indicating 62%. My mechanical gauge is indicating 59%. My heat pump has to work to keep it down at that level, currently and unusual the outside humidity is now 38%. Likewise, my HP has been on since 2001. I would suggest you purchase a gauge to measure humidity and see what you have.

p.s. I believe what Bud was saying above is, if the HP is sized correctly, it will run long enough to cool down the inside and remove the humidity from the air. An over sized one will satisfy the temperature faster and will not run long enough to pull the humidity out of the air. If you have a humidistat, even thought the temperature may be satisfied, the HP will continue to run and remove humidity from the air until the humidistat setting is satisfied as well.
 
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Old 05-09-13, 02:35 PM
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I think I understand Mike1555's explanation a little better but I want to add humidity, not reduce it. The air in the house is too dry for my respiratory problems. Am I understanding what you said correctly, or am I just too dense to comprehend it?
 
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Old 05-09-13, 03:26 PM
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You are doing good, better than my explanation. The idea I was suggesting was to address the insulation and air sealing on your house to make it more efficient. In doinf so, your current heat pump would run less and therefore remove less moisture. Where most people want to decrease the moisture, you want to increase it. The caution I see is, as Mike asked, what reading do you have now. If you already have 60%RH, increasing it starts to move into mold growth. If you are running way below that number then perhaps something is removing more moisture than needed and instead of adding moisture we correct the item that is removing too much.

Do you have a humidity gauge? If not, there are inexpensive ones that will give you a reference for starters.

Mike also asked if you have a humidistat that allows you to set the humidity desired instead of just the temperature.

Bud
 
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Old 05-09-13, 03:56 PM
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I have not checked the existing humidity level in the house but will do so ASAP. I feel very confident that the humidity is below 50% because the A/C and heat pump remove it. I was planning to install a humidistat along with the humidifier to control the levels of humidity. Do you think a portable humidifier would be a better solution??
 
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Old 05-09-13, 05:30 PM
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I think it will be interesting to see what your house humidity is. Here is one link to the subject Humidity Control.
 
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Old 05-09-13, 06:01 PM
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Great link Mike.....I'll give you an update on the humidity level as soon as I check it.
Thanks to all for your input on this matter.....buzcar
 
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Old 05-10-13, 04:44 AM
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A properly sized system should keep the RH around 52%-56%. Most systems will not pull below 50% with out a De-humidification control. Also any thing above 55%- 60% will make conditions right for mold to start growing.
 
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Old 05-10-13, 07:43 AM
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Should a properly sized system keep the RH around 52%-56% during both phases, i.e., heating and cooling?
 
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Old 05-10-13, 12:33 PM
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cooling, Heating will depend on many factors but with a heat pump in a warm climate like FL Id think id would be very difficult to get the RH below 50% unless your house is very leaky
 
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Old 05-10-13, 01:46 PM
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I guess I am confused again.....if the house is very tight wouldn't the air get very dry while running the A/C or heat? I was of the opinion that A/C extracts water from the air and heat dries it up, thereby lowering the RH.....is that true?
 
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Old 05-10-13, 04:36 PM
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Hi again,
There are two variables working here, the moisture in the air and the temperature. In the summer high temperatures with reasonable high moisture levels will become very humid air when cooled to 75. Here is a calculator to play with. Temperature, Dewpoint, and Relative Humidity Calculator
90 outside air at 60% RH goes to 97% RH when cooled to 75.

Now, few homes are very tight. A typical tight home will exchange all of its air every three hours. Tighter than that and the home will have a fan running or air exchange system to make up for what leakage is not providing. So every 3 hours or sooner you get all new air with all of the moisture it brings with it. That's the summer.

When the heat is operating, you are correct, the heated air drops in RH and seems dryer, not because any moisture has been removed, but because it can hold more moisture at a higher temperature. If your outside temperature dropped to 40 @ 60% RH and you heated it to 70, its RH would go to 20% and you would definitely be wanting to add moisture.

It sounds like you are having comfort issues in both summer and winter. For winter we will eventually get one of the HVAC pros to comment on adding a humidifier to a heat pump. But in the summer we are still wondering what is happening to all of that moisture. Once you give us a reading we will know where we are starting from.

Bud
 
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Old 05-11-13, 04:50 AM
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Great explanation Bud. I'm still not sure I completely understand it but it certainly makes sense. I haven't purchased a Hygrometer yet but plan to do that today. As soon as I get an RH reading I will post it. Thanks for the info....buzcar
 
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Old 05-11-13, 10:44 AM
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Record the temperature at the same location as well. Temp and RH are necessary to know the moisture level.

Bud
 
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Old 05-11-13, 12:11 PM
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One thing that may help in increasing the blower speed if possible - reduces dehumidification, increases actual cooling.

Running the fan continuously may help by re-evaporating moisture back into the air when the a/c shuts off.

Keeping the humidity too high can cause mold growth, so be careful.
 
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Old 05-12-13, 04:29 AM
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The temperature/humidity device was install at noon yesterday and the current readings today at 7:30am are as follows:

Humidity = 55 (55 max/49 min)
Temperature = 75 (86 max / 75 min)
 
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Old 05-12-13, 04:35 AM
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That's exactly where airman suggested it would be, he is good. Now, this is basically a summer condition (air conditioning). Is this too dry for you or is it the heating season that bothers you?

Bud
 
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Old 05-12-13, 05:09 AM
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Actually I can't say that either season truly bothers me. Since I have COPD I guess I was just hoping that adding some humidity to the house would improve my breathing condition. Based on the education I have received from you guys I've come to realize it's not that simple. It appears that the summer conditions are within the acceptable range but I won't know about the winter conditions until winter. From what I've learned I'm thinking that a vaporizer may help my condition if the readings indicate the air is too dry when heating. Comments please.....
 
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Old 05-12-13, 10:03 AM
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I think you are on track. The advantage of a localized vaporizer is it can help with a bedroom for sleeping without soaking the entire house. I'm not sure if there are other issues with vaporizers and breathing issues so be sure to check.

Your original question still stands, can you add a humidifier to the heat pump air handler for winter use? Can anyone provide an answer to that? Or should a free standing humidifier be used?

Bud
 
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Old 05-12-13, 12:47 PM
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Well Bud, apparently we have gone full circle with this thing. Now you are asking the same questions I started out with!

Just kidding.....the info I have received is great....thanks for all the help....Buz
he
PS
I dropped the A/C setting down to 75 and the humidity also dropped to 49%. The house is a little cool at 75 so I kicked it back up the 76 to see what the humidity does. I believe anywhere from 45% to 55% is ideal. I'll let you know how it works out......
 
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Old 05-13-13, 10:28 AM
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5/13/13 @ 1 pm today, the outdoor temp is 76 and the relative humidity is 56%. We will be having a "cold" front moving thru later today which will result in lower RH. See how your indoor reading may change. This coming july/aug should show some interesting results.
 
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Old 05-13-13, 11:03 AM
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Can I assume that humidity indoors is predicated on the humidity level of the air processed by the AC unit, not the temperature of the air indoors or outdoors?
 
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Old 05-13-13, 11:21 AM
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NO RH will depend on outside levels, How tight your home is are isn't, Bath and kitchen EX fan use and run times, HVAC fans in Auto or on position, and respiration, VB below the slab. Did I forget anything?
 
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Old 05-13-13, 12:01 PM
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Forgive me airman.1994 but....... I have no idea what that meant beyond "NO RH will depend on outside levels".
 
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Old 05-13-13, 01:48 PM
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RH will depend on those issues as well
 
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Old 05-13-13, 02:00 PM
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I think I get it now.....thanks
 
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