DIY Home Improvement, Remodeling & Repair Forum > Appliances > HVAC > Daikin Mini-Split - Issue with Humidity




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Old 07-18-2014, 08:51 AM  
brewer55
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Default Daikin Mini-Split - Issue with Humidity

I had a Daikin mini-split system (Model FTXN09KEVJU5) installed this past February. Although the air conditioning seems to be working well (blowing cold air) and the temperature is where it should be for the setting, the humidity in the room when I get up in the morning is rather high and in the mid 60's. (I put a temperature and humidity device on my nightstand). It used to be in the low 50's. Anyway, I started doing some troubleshooting and I noticed that the PVC for the drain (condensation removal) was bone dry. My first thought was it was blocked maybe because insects or a critter made a home in the pvc. I ran a metal snake all the way to where it stopped where it elbows into the unit (on the outside wall of the house) and there was no apparent blockage. I did not do the installation and am a little gun shy about how to go about removing the front panel and doing an inspection from inside the unit to see if there is some blockage of the drain pipe.

Any advice would be appreciated.


Daikin Mini split.jpg   Daikin mini split 2.jpg  

Last edited by brewer55; 07-18-2014 at 09:06 AM.
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Old 07-18-2014, 10:18 AM  
Wuzzat?
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It could be oversized and so the air feels clammy.

IIRC, there is a limit as to how fast you can pull the grains of moisture out of the air and this does not show up on the psychrometric chart. Renting a dehumidifier may confirm/disprove this idea.

http://htalk-ef.com/articles/Cooling...dification.pdf



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Old 07-18-2014, 10:58 AM  
brewer55
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Quote:
Originally Posted by Wuzzat? View Post
It could be oversized and so the air feels clammy.

IIRC, there is a limit as to how fast you can pull the grains of moisture out of the air and this does not show up on the psychrometric chart. Renting a dehumidifier may confirm/disprove this idea.

http://htalk-ef.com/articles/Cooling...dification.pdf
Since my post, I went outside and uncoupled the PVC connection at the place where the flexible hose was connected. I set the unit to 'Dry' which removes moisture/humidity from the air, and also attempts to maintain the temperature. I am getting a drip, drip, drip now. I'm not sure what is or was going on because I never found an obstruction. The humidity reading has dropped from 65% to 59% in the room in less than an hour. I'm going to continue to monitor the situation. In the meantime, does anyone know what the avg humidity level should be in a properly air conditioned room?
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Old 07-18-2014, 12:05 PM  
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I just spoke with my HVAC guy and he believes there is a problem and that I should be able to drop the humidity to 50% with no problem. He thinks there may be a leak with the coolant and that perhaps the flanged fitting that meets the unit could be where that is occurring. Anyway, a visit from him is in order.
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Old 07-18-2014, 12:52 PM  
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Quote:
Originally Posted by brewer55 View Post
I set the unit to 'Dry' which removes moisture/humidity from the air, and also attempts to maintain the temperature. I am getting a drip, drip, drip now.
So you have done the dehumidifier experiment!

Wiki knows all
"Humans can be comfortable within a wide range of humidities depending on the temperature — from thirty to seventy percent - [4] but ideally between 50%[5] and 60%.[6]"
and [human] women have a somewhat different comfort range.

Our central HVAC first drops the humidity and then drops the temperature. In this first hour or so you can feel more comfortable without the temperature dropping at all.

If your unit is oversized, I'm sure there are ways to make it less efficient but they will waste energy.
Or sell your unit on e-bay and get a smaller one.

With
BtuH Cooling: 9,500
how big is the room? 10' x 12'?
Grainger has rules of thumb for sizing these things based on room size.

Last edited by Wuzzat?; 07-18-2014 at 01:02 PM.
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Old 07-18-2014, 05:51 PM  
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Using compressed air on the drain tube is easier and no danger of puncturing the condenser.
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Old 07-19-2014, 09:01 PM  
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Could be that the exterior unit is mounted too low, obstructed by plants or somehow the moisture in the ground is affecting it.
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Old 07-25-2014, 04:39 AM  
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You will need to ad least learn to raise the front cover ( " hood " ) of the inside unit to remove and wash the filter .

Do you still have water dripping from the condensate drain , if you switch from dry to cool ?

If your unit is a higher efficiency / SEER model , it probably has a variable speed inverter drive compressor . If so , I read being over sized is not as big an issue . The compressor slows down to suit the cooling load / needs .

God bless
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God bless
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Old 08-03-2014, 05:26 AM  
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My HVAC guy came out a few days ago and he spent an hour troubleshooting. He could not find anything wrong and, after resetting it by pulling the power, it seemed to be working ok. All day long the humidity in the room never got above 55f and the condensation hose outside was dripping. It seem all was good. Well, this morning I woke up feeling a little sticky and I looked at my temp & humidity meter and it was showing 65%. I went outside and the evaporation hose/PVC was bone dry again. So, it lowers the temperature to where I set it but, it is no removing the moisture from the air. He showed me on the remote how you can do a self test to see if there are any error codes and it is not registering any.


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