How to install a central dehumidifier?

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  #1  
Old 12-18-16, 05:34 AM
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How to install a central dehumidifier?

I was wondering if it's not too difficult for a home owner to install a central dehumidifier themselves. Any links to step by step instruction is much appreciation. In my previous home the dehumidifier has a hose that drips the water to the floor drain. I was wondering if there is a central dehumidifier system that does that so I don't have to dump out the water every so often.
 
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Old 12-18-16, 07:25 AM
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A central dehumidifier is your central air conditioner. However, you can't run them in the winter time. What you saw in your other house was likely your drain for the central A/C, or was the drain for the condensation from exhaust gases from the furnace.

You need to see my post on your other thread about condensation on your windows.
 
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Old 12-18-16, 10:47 AM
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They do make central dehumidifiers that require ducting. However, they are fairly pricey.
If you have central air that should also be able to control humidity.
 
  #4  
Old 05-15-18, 10:35 AM
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I'm contemplating installing a whole house dehumidifier myself. It is very humid during the summer months, and although my A/C does a good job, I don't want to have to set it to 70-72 degrees simply to get the humidity down. I'd be fine with 75-78 (actually prefer it) if the humidity was lower. I've been looking at the Honeywell DR120. The installation sounds pretty straightforward, but I do have a couple questions. The first is, why are there three duct connections (one 6" and two 10")? Second is, do I have to interface the controls with my existing thermostat, or can the dehumidifier stand alone? Is it necessary for my air handler's fan to be running when the dehumidifier is on, or does the dehumidifier have its own fan?

Links to manual (leaning towards install option A with dedicated return): https://customer.honeywell.com/resou...69-2690EFS.pdf

Maybe the 6" "supply" connection is used only for the fresh air intake install option (outside air)?
 
  #5  
Old 05-15-18, 01:34 PM
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Thermastor has videos that can help you out https://www.thermastor.com/
 
  #6  
Old 05-17-18, 07:53 AM
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I opened up my air handler yesterday evening with the intent of lowering the fan speed to help reduce humidity, and found that the fan speed was already on the lowest setting. Upon opening the cover, I found a bit of black mold on the blower housing and all over the wiring for the blower. Also, the run capacitor has rust on it and there were water droplets on the blower motor. Evidently, there is a moisture issue due to one reason or the other.

Considering my home feels a little more humid than I feel it should (I ordered a humidity meter to verify), my best guess is that the unit is over-sized for my home. Even on the lowest setting, the air comes out of the vents with a lot of velocity (I can feel air from the floor vents all the way up to the ceiling). It's a 2.5 ton unit and my home is just under 2,000 sq ft, well insulated, all new windows, R-55 in the attic. What else could the issue be? I don't run the fan unless the AC is on, so moisture collecting on the fan motor and housing above the coil seems to be like there is too much velocity. My coil pan also had a little standing water in it when the unit is off, but that may be normal. I primarily added it for the winter time anyhow.

I should mention that the air handler is a Goodman ARUF303016CA (upflow configuration) and is about 5 years old. The heat pump is also a Goodman and is 15 years old. Yes, it is very old, but it's still kicking and the air blows very cool.

I should also mention that my return ducts are caked with a couple inches of dust. Would this restrict airflow enough to cause the blower to run faster and draw moisture up onto the blower housing, motor, and wires?

Grasping at straws here, but I also have a 12" diameter 4' long return duct connected to return box about 2' away from the coil. I added this return several years ago because there was not an existing one in the basement (350 sq ft of finished space). Was this a no-no? I suppose having such a large return in a basement so close to the air handler may not be a good thing. Perhaps the (much) cooler air in the basement is cooling the warmer air from the upstairs returns (two of them) so that the air passing over the coil isn't as warm as it should be and thus not removing as much humidity as it should? I have a damper on the basement return, so I can easily close it off.
 

Last edited by mossman; 05-17-18 at 10:31 AM.
  #7  
Old 05-17-18, 11:05 AM
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I believe I may need to either reduce the size of the basement return, or close it off altogether. Here are some calculations I derived based on some limited research:

2.5 ton unit x 400 CFM/ton = 1,000 CFM minimum required return air.

Referring to grill size only at 2 CFM/sq in, I have three 16"x16" return grilles, which is a little over 1,500 CFM. If I omit the basement return, I'd be back to 1,000 CFM, which is where I need to be. Not sure if this has anything to do with my moisture issue inside the cabinet or humidity level in the house, but I figured I'd bring it up.
 
  #8  
Old 05-22-18, 04:13 AM
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To @ charlie2 and mossman, this is a description of my installation for comparison. My house is 2000 sq. ft. on 1 floor with R-19 walls and R-50+ in the attic. It was built 20 years ago, and is located just north of Pittsburgh, Pa. 18 years ago I finished the basement which has about 1/2 the wall surface below grade. All walls are insulated to R-19. I have a 3 ton A/C unit set for 75 degrees in the summer. I run the blower fan 24/7 year round. The duct system has out of the wall supply registers on the main floor with "high/low return grills 1 or more per room and 6 supply registers (ceiling mounted) in the basement with 3 large returns. I too have a humidity problem when the A/C runs as do many houses. I run a 70 pint dehunidifier in the basement set at 40% all summer. AS far as the A/C unit and fan speed, the temperature drop across the indoor coil should be between 15 and 20 degrees. mine runs 18-19 degrees. I opted for a portable unit due to cost to buy and cost to operate. My home is comfortable year round. I did not answer any questions on the dehumidifier you referenced since I do not have 1 and have only seen 2 installed. Hope this helps in your search.
 
  #9  
Old 05-22-18, 09:37 AM
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I run the blower fan 24/7 year round.
I've heard this is not a good thing, and could be a significant contributing factor to your humidity problem. Running the fan after the AC cycle is pulling moisture off the coil and pumping it back into your house. Obviously not a good thing. Have you experimented with not running the fan and observing the humidity levels?
 
  #10  
Old 05-22-18, 10:28 AM
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some people claim that the water on the coil will increase the humidity level in the house. I disagree since the amount of water on the coil is minimal. It may raise the humidity a very slight amount but my home is not a laboratory with gauges sensitive enough to measure that amount of humidity. It would take more than the water on a wet coil to effect the humidity in my home or yours. As far as running the blower fan 24/7 , I also do it to even out the temperature in my home and for the electronic air cleaner to grab as much pollen and dirt as possible. I have been running my blower 24/7 for 40+ years so why change now.
 
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