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Humidity and open cell foam

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#21 ·
Add the dehu location and duct connections to the above drawing. We need temp/%RH in the home and at the a/c supply while cooling. How much water is removed by the dehumidifier per hour.

The duct connections and the a/c setup are critical to humidity control of a home.
The attic temp/%RH cycle throughout the day is also a clew.

Regards Teddy Bear
 
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Discussion starter · #22 ·
teddy bear said:
Add the dehu location and duct connections to the above drawing. We need temp/%RH in the home and at the a/c supply while cooling. How much water is removed by the dehumidifier per hour.

The duct connections and the a/c setup are critical to humidity control of a home.
The attic temp/%RH cycle throughout the day is also a clew.

Regards Teddy Bear
Click to expand...

The dehum is attached to the HVAC unit in the sketch. There is one supply in the "attic" section and 2 supplies in the living area. There is one return in the living area and no return in the attic section.

I don't have a continuous humidity monitor in the attic section, but since installing spray foam the attic section when I manually check it is within a few degrees and a few percentage points of the living area. I will recheck with my handheld humidity probe later today.

ETA: I have an Aprilaire 95pint dehumidifier
 
#23 ·
So the dehumidifier is independent of the a/c, right? If so measure the air temp/%RH being sucked into the dehu and the temp/%RH dehu supply.

Do the same for the a/c, temp/%RH in the home or at the a/c returns and at the a/c supplies closets to the a/c. Again, this tells about the a/c function sensible/latent removal. These two units can remove 4 lbs./hour + 3lbs./hour/ton of a/c.
If working right, should be +10 lbs. per hour.

Regards Teddy Bear
 
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Discussion starter · #24 ·
teddy bear said:
So the dehumidifier is independent of the a/c, right? If so measure the air temp/%RH being sucked into the dehu and the temp/%RH dehu supply.

Do the same for the a/c, temp/%RH in the home or at the a/c returns and at the a/c supplies closets to the a/c. Again, this tells about the a/c function sensible/latent removal. These two units can remove 4 lbs./hour + 3lbs./hour/ton of a/c.
If working right, should be +10 lbs. per hour.

Regards Teddy Bear
Click to expand...
The dehumidifier not independent, it is placed in series with the HVAC. It goes return-dehumid-HVAC-supply.
 
#25 ·
Need a/c return temp/%RH info.

Regards Teddy Bear
 
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Discussion starter · #27 ·
OK, I whipped out my handheld hygrometer and did some recordings.

The readings matched the readings from my Ecobee almost exactly, EXCEPT for the third floor.

In the living space on the third floor, I recorded the following:

55.6% H
73.6°F

In the attic:
78.5% H
74.1°F

The Ecobee shows:
73%H
75°F

The Ecobee is essential on the wall between the 2 spaces. The spaces are separated by a double door.

There is no doubt that the attic space is significantly wetter. You can feel it. But I wonder why the Ecobee is reading such a high humidity in the living space. Living space feels pretty comfortable.

Any help would be appreciated.
 
#28 ·
Where is the the a/c supply temp/%RH?

Regards Teddy Bear
 
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Discussion starter · #29 ·
Supply:

73.4%
56.2°F

I read through the forum and learned about plugging the hole behind the thermostat to get a more accurate reading, which I think was a major problem all along. I also purchased a small stand alone WiFi temp/humidity gauge that I will place in the living area for another set of "eyes". I will switch this to the attic to monitor the temp/humidity separately if the Ecobee becomes mores accurate.

The attic is obviously much more humid despite being "inside" the conditioned space. It has one very small supply and no return so I can't expect miracles, but is this a problem? My HVAC installer will not add a return from this area due to code issues. He's discussing a separate dehumidifier for the attic space.
 
Discussion starter · #30 ·
Another question: which sensor actually controls the humidifier turning on or off, the one in the Ecobee or the sensory from the Aprilaire in the return?
 
#32 ·
ckelly14 said:
Supply:

73.4%
56.2°F

I read through the forum and learned about plugging the hole behind the thermostat to get a more accurate reading, which I think was a major problem all along. I also purchased a small stand alone WiFi temp/humidity gauge that I will place in the living area for another set of "eyes". I will switch this to the attic to monitor the temp/humidity separately if the Ecobee becomes mores accurate.

The attic is obviously much more humid despite being "inside" the conditioned space. It has one very small supply and no return so I can't expect miracles, but is this a problem? My HVAC installer will not add a return from this area due to code issues. He's discussing a separate dehumidifier for the attic space.
Click to expand...
Sorry about the confusion.
I am attaching a layout with the typical temps/RHs.

Tell us one more time what your a/c supply temp-%RH.

Regards Teddy Bear
 
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Discussion starter · #33 ·
teddy bear said:
Sorry about the confusion.
I am attaching a layout with the typical temps/RHs.

Tell us one more time what your a/c supply temp-%RH.

Regards Teddy Bear View attachment 824852
Click to expand...
My setup is slightly different: Return-dehumid-HVAC-supply (i.e. there is not a separate intake for the dehumid), but the data above was taken from the supply:

73.4% RH
56.2°F

I will recheck tonight if that seems to be erroneous.
 
#34 ·
ckelly14 said:
My setup is slightly different: Return-dehumid-HVAC-supply (i.e. there is not a separate intake for the dehumid), but the data above was taken from the supply:

73.4% RH
56.2°F

I will recheck tonight if that seems to be erroneous.
Click to expand...
The a/c supply temp/%RH is about right for an a/c only operation of a/c only. With a/c and dehumidifier running, I would lower dew point

at the supplyl


Regards Teddy Bear
 
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Discussion starter · #35 ·
teddy bear said:
The a/c supply temp/%RH is about right for an a/c only operation of a/c only. With a/c and dehumidifier running, I would lower dew point

at the supply

Regards Teddy Bear
Click to expand...
Perhaps I'm not understanding, but I calculated the dew point as 47°F, same as in your example. The temp is quite a bit lower due the different set up.

Can you explain? Thanks
 
#36 ·
Yes, there an additional 300 cfm of air flowing through the duct because the dehumidifier supply blowing into the a/c supply as well as the a/c. 300 cfm more dry air means more moisture removed. A little complicated by it is the way it works.

Make sense? More air flow with same levels of moisture removal = more moisture removed.


regards Teddy Bear
 
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