Best AC for Dehumidifieng?

[oil]

Hello,

i am looking to buy another AC for my Office,
our house is pretty good insulated, so i am looking for a 18.000 BTU Unit.
I have a Misubishi Inverter in the Sleeping Room and i love it, espacially the silent mode is mindblowing, the frogs outside are much louder then the AC

anyhow.... when it comes to Dehumidifieng that Machine doesnt seem to be as awesome as i like it to be, better said... The Dehumidifieng function/ setting on the AC takes very long and ist not much effective according to how it feels.

my main issue is, that the Temperature doesnt bother me too much, but the Humdity makes me lazy.
In our Office / Living Room we have those days 28-30 Degrees C, but the Humidty is about 80% which feels unbearable to me.
Hence i am wondering if you guys could share some insight based on experience which other AirCon Brand might work better as for the Dehumidifieng part.
thx.

[kmanonmaui]

Hence i am wondering if you guys could share some insight based on experience which other AirCon Brand might work better as for the Dehumidifieng part.
thx.

Hi. I have no personal experience on this matter, but was curious myself. I found this link which might be helpful, http://www.livestrong.com/article/27689 ... -climates/

[Klondyke]

Hello,
anyhow.... when it comes to Dehumidifieng that Machine doesnt seem to be as awesome as i like it to be, better said... The Dehumidifieng function/ setting on the AC takes very long and ist not much effective according to how it feels.

my main issue is, that the Temperature doesnt bother me too much, but the Humdity makes me lazy.
In our Office / Living Room we have those days 28-30 Degrees C, but the Humidty is about 80% which feels unbearable
thx.

Wondering why to bother with the "dry" mode? Once you run in "cool" mode some 26 - 27deg the humidity will go down as well.

[Klondyke]

BTW. How did you make "good insulating"?

[oil]

well for the house we used the
15 cm Q-Con Blocks, they have a R-Value of 1.5 and are the best stones you can built with in TH those days when it comes to Insulation / Block Heat Transfer.
We also put Double Glazed Windows 5 / 10 / 5 from http://www.thaiconch.com in most Rooms besides the Wet Rooms.
So much for the Walls.

Our Roof is White Metalsheet with this funny Insulation layer below.
Then we have a 1 - 2 meter attic, witch animal protected openings on the side where the wind can carry the heat away freely.
below that we have planned to put some 2 cm Cement Boards thati could walk on the Attic nicely and use it as storage, but those are pretty expensive and inanely heavy ... hence... they are still missing
however below the imagined Cement Board comes two layers of Glass Woold, (layed overcross)

Reason i am saying we have a good insulation is that when we had AC running in the Sleeping room and after we get up... it stays cool in the Room for the Full day... Only to the evening it gets slightly warmer in there.

[Andyfteeze]

that reference to dehumidifiers looks suspiciously like a conversation about refrigerative aircon and evaporative aircon.

[kmanonmaui]

:) well for the house we used the
15 cm Q-Con Blocks, they have a R-Value of 1.5 and are the best stones you can built with in TH those days when it comes to Insulation / Block Heat Transfer.
We also put Double Glazed Windows 5 / 10 / 5 from http://www.thaiconch.com in most Rooms besides the Wet Rooms.
So much for the Walls.

Our Roof is White Metalsheet with this funny Insulation layer below.
Then we have a 1 - 2 meter attic, witch animal protected openings on the side where the wind can carry the heat away freely.
below that we have planned to put some 2 cm Cement Boards thati could walk on the Attic nicely and use it as storage, but those are pretty expensive and inanely heavy ... hence... they are still missing
however below the imagined Cement Board comes two layers of Glass Woold, (layed overcross)

Reason i am saying we have a good insulation is that when we had AC running in the Sleeping room and after we get up... it stays cool in the Room for the Full day... Only to the evening it gets slightly warmer in there.

I'm just guessing, but makes sense to me....
1. 8 include concrete block, by itself without gaps in-between, solid grouted or not, has a very poor R value...heat/cooling transfers easily
2. Sounds like you are chilling down your walls at night, benefiting from that retained coolness during part of the day, then running your a/c all night to remove the heat in the block that built up during the day.
3. My guess is that you experience the moistness mostly during the day; not sure how to best address this...possibly coating the interior of your block with something that moisture cannot penetrate easily (assuming you have already painted the outside)
4. A regular double pane window (at least our kind) only have an R value of about 1.5-2.0 (https://www.google.com/url?sa=t&rct=j&q ... MmnRutnFTg)
In summation, your room is very poorly insulated and you are probably wasting money in the cooling costs; the humidity issue is likely related to the blocks (cement) being so moisture permeable. Again, just my guess...sure others reading this can provide more accurate information.

[kmanonmaui]

These links may provide some useful information:
https://energy.gov/energysaver/moisture-control
"Moisture Control in Walls: It is a myth that installing vapor barriers is the most important step for controlling moisture in walls. Vapor barriers only retard moisture due to diffusion, while most moisture enters walls either through fluid capillary action or as water vapor through air leaks."

https://advice.thisoldhouse.com/archive ... 23295.html
"The problem being encountered here is not interior generated moisture, but moisture that is being driven through the exterior walls where it encounters a cold, impermeable air barrier on the inside. Here it condensates. This type of problem did not exist before the advent of air-conditioned homes and the use of absolute air barriers such as plastic. Those interior walls must let the moisture continue on through. Similarly, wall papers with plastic coatings or metalic finishes should not be used on exterior wall surfaces as they also form impermeable barriers." or other related posting.

Hope that helps,
-k-

[Sometimewoodworker]

:) well for the house we used the
15 cm Q-Con Blocks, they have a R-Value of 1.5 and are the best stones you can built with in TH those days when it comes to Insulation / Block Heat Transfer.
We also put Double Glazed Windows 5 / 10 / 5 from http://www.thaiconch.com in most Rooms besides the Wet Rooms.
So much for the Walls.

Our Roof is White Metalsheet with this funny Insulation layer below.
Then we have a 1 - 2 meter attic, witch animal protected openings on the side where the wind can carry the heat away freely.
below that we have planned to put some 2 cm Cement Boards thati could walk on the Attic nicely and use it as storage, but those are pretty expensive and inanely heavy ... hence... they are still missing
however below the imagined Cement Board comes two layers of Glass Woold, (layed overcross)

Reason i am saying we have a good insulation is that when we had AC running in the Sleeping room and after we get up... it stays cool in the Room for the Full day... Only to the evening it gets slightly warmer in there.

I'm just guessing, but makes sense to me....
1. 8 include concrete block, by itself without gaps in-between, solid grouted or not, has a very poor R value...heat/cooling transfers easily

In summation, your room is very poorly insulated and you are probably wasting money in the cooling costs; the humidity issue is likely related to the blocks (cement) being so moisture permeable. Again, just my guess...sure others reading this can provide more accurate information.

You missed the fact that Q-Con is the name of one of the better AAC blocks, this means that the room, rather than being poorly insulated is the opposite, also AAC blocks themselves are not very, if at all, moisture permeable.

To address the original question: how big is your office?
You have good insulation, if you are getting a regular AC unit, probably also if it's an inverter, DO NOT OVERSIZE. Bigger is not better with AC units specially if humidity is the main problem.

The AC unit is most, and economically, effective at dehydration when it's running in cool mode, if you oversize then it will run for a very short time to cool down the room and so do very little to the humidity.

Do not believe any of the Thai charts on AC to room size they all recommend bigger than you need.

In your case under sizing would be more effective.

[kmanonmaui]

You missed the fact that Q-Con is the name of one of the better AAC blocks, this means that the room, rather than being poorly insulated is the opposite, also AAC blocks themselves are not very, if at all, moisture permeable.

You are correct, I don't know anything of Q-Con blocks vs. other concrete based blocks. Looks like this was discussed a few years ago on this forum (viewtopic.php?f=7&t=4753) and possibly worth a look.

[kmanonmaui]

btw, not questioning your statement on the quality of Q-Con Blocks, but I couldn't find any study, data or fact sheet on with regards to their moisture resistance, even on the manufactures website (http://www.qcon.co.th/) when translated, but a lot about how much better they are for insulation (both sound and temperature) than other blocks.

[kmanonmaui]

I couldn't find any study, data or fact sheet on with regards to their moisture resistance

Slight correction. I did just find this site (http://www.poratthima.com/sites/default ... lish_1.pdf) which states:
"Furthermore, it eliminates the mold problem occurring from humidity because it absorbs water more slowly than some other materials do."


And, if further states, as you correctly indicated, "Q-CON” is an excellent heat and acoustic insulator, not only reducing heat transfer from out site to inside building 4-8 times better than clay brick does but also not retaining heat inside itself. Thus you could save electric bills regarding air conditioning system up to 30% and the capacity of air conditioning systems could be reduced.

[oil]

thx to all, espacially to sometimeswoodworker

i also believe the Thais oversize the AirCons all the time, but i didnt know that the dehudifieing works the best in the cooling process
but after that being said... it makes perfect sense, cause after i switched on AC in the sleeping room, humidy falls rapidly with the temperature..

i was planning on using the Mitsubishi MSY-GN18VF-T1 - 17700 BTU - SEER 21 / 2450 KWH / Device from
http://ptairsupply.com/index.php?name=p ... ducts&id=7
those guys did the other AirCon and it was good service for us in Chiang Mai Area.

My Office is Roughly 20 sqm with a Ceiling Height of 3 meter with one Big Window, however its not a closed room its more open to the Living room but can be closed with some type of curtain, but not a real door.
I used the - http://www.calculator.net/btu-calculato ... &x=61&y=15
for my Wildguessing on the BTU size..
If i assume a 7 Degrees C decrease in Temperature for that Room and good insulation i would need only..
You will need 2,408 BTU/hour or 705 watt.
that seems rather low ... thou the 12.000 BTU AirCon we have in the Sleeping Room cools it down to 26 C (My sleeping temperature) in no time. So even the Sleeping Room one seems oversized.
However if i would add the whole living room size (50 sqm) + Office to the Calucation (20sqm)
the BTU calculator comes up with 5,598 BTU/hour or 1,640 watt.

Mhmm.... i might go to the 12.000 BTU machine then... or does this sound too insane for 70 sqm ...????

[Andyfteeze]

there is a very good reason thais over spec their airconditioners. They build pizza ovens and call them homes. The aircon has to be on all night just to cool the walls down.
For a typical thai build, I have an 18,000 btu Daikan unit and it works well for a 40m2 area. In my new build, I will be putting a 9,000btu unit in for an area of 40m2. Even without windows its far far cooler than the current house. Double Qcon blocks downs stairs with 50mm foam in the cavity.
If the house is well insulated, you dont need thai sized units.
Qcon blocks do absorb some water. But its about 1/10th of normal bricks. You would need a week to fully saturate one where as a normal brick will spong within the hr. They float on water due to the amount of air trapped inside, hence their great thermal properties. Because they look like bricks, people incorrectly assume brick properties and so assiume brick construction techniques. Normal bricks have cavity walls to stop water ingress. I used a cavity wall as extra insulation.

[Sometimewoodworker]

thx to all, espacially to sometimeswoodworker

i also believe the Thais oversize the AirCons all the time, but i didnt know that the dehudifieing works the best in the cooling process
but after that being said... it makes perfect sense, cause after i switched on AC in the sleeping room, humidy falls rapidly with the temperature..

i was planning on using the Mitsubishi MSY-GN18VF-T1 - 17700 BTU - SEER 21 / 2450 KWH / Device from
http://ptairsupply.com/index.php?name=p ... ducts&id=7
those guys did the other AirCon and it was good service for us in Chiang Mai Area.

My Office is Roughly 20 sqm with a Ceiling Height of 3 meter with one Big Window, however its not a closed room its more open to the Living room but can be closed with some type of curtain, but not a real door.
I used the - http://www.calculator.net/btu-calculato ... &x=61&y=15
for my Wildguessing on the BTU size..
If i assume a 7 Degrees C decrease in Temperature for that Room and good insulation i would need only..
You will need 2,408 BTU/hour or 705 watt.
that seems rather low ... thou the 12.000 BTU AirCon we have in the Sleeping Room cools it down to 26 C (My sleeping temperature) in no time. So even the Sleeping Room one seems oversized.
However if i would add the whole living room size (50 sqm) + Office to the Calucation (20sqm)
the BTU calculator comes up with 5,598 BTU/hour or 1,640 watt.

Mhmm.... i might go to the 12.000 BTU machine then... or does this sound too insane for 70 sqm ...????

You say that you have a 12,000 BTU AC in your bedroom and that it cools down really quickly?

If so then I would suggest that you get a new smaller 9,000 inverter one for your bedroom and put the 12,000 one in the office. I suggest that as you almost certainly have a much bigger unit in your bedroom than you need, as it's an inverter it isn't a big mistake.

The reason why AC is most efficient at dehumidification when it's on cool is that if you just have one on dry it is supposed to cool the air extract water then warm the air, so on cool you skip that last step.

One further point how low is the humidity getting in your bedroom when you get the temperature down to 26 degrees?