Indoor Humidity Issues

[dia1]

15 hours ago, farang51 said:

Please be aware that when you cool down, the humidity rises. So, if you have 32 degrees and a humidity of 62 percent outside, and you cool down to 25 degrees indoor, the indoor humidity will rise to 96 percent!

 

You will find a humidity calculator here:

https://www.lenntech.com/calculators/humidity/relative-humidity.htm

 

Usually, fungus and mold spores shouldn't be a problem if you keep the humidity below 60 percent. It may be better to open all the windows to create airflow, as @pikao wrote. A closed room with a high temperature and humidity works as a petri dish; if you have airflow, you can have higher temperature and humidity without problems. If you must use aircon, try setting it on a higher temperature.

 

Temperature doesn't change the amount of humidity in the air... only the relatively humidity. When using an AC, the RH should go down as it is pulling in moisture during the cooling process and venting it outside as condensation... at least it should when working properly. This is why your nose will get dry when running the AC too much in some places.

 

 

4 hours ago, moe666 said:

You did not mention on what setting you set your coolers but you need to set them on the lowest temp. they have to number one cool the place and to evacuate the moisture. and yes you need to shut the doors.

check the drain pipe off the evaporators and see how much water is draing out. It should start drying out soon with the end of rainy season, that should help. Also where is your house built maybe on an area where they get a lot of ground water.

 

I'm right around Thong Lor area. I'm setting the AC to 16 degrees with the highest fan speed when trying to dehumidify. That's the lowest it goes.

 

 

4 hours ago, sometimewoodworker said:

 

 

You don’t have the correct dehumidifiers and you are not running them the correct way.

 

you need this kind.

 

with a discharge hose

running most of the time.

 

it’s not cheap but will drop the humidity in my workshop by 20% running for about 10 hours. That is a space that is very significantly larger than it’s designed for, about 300 cubic metres 

 

Both of the humidifiers have discharge hoses. They are large, standing dehumidifers, but they are not industrial ones like the ones pictured. The radiators of the two I have now are already quite noisy, generate a lot of head, and are probably running my electric bill through the roof. If something bigger is required to get to a normal humidity, I think there is some bigger issue at play.

 

 

3 hours ago, sometimewoodworker said:

It makes complete sense. Humidity is a measure of the ability to hold water vapour in the air. The higher the air temperature the greater the amount of water it can hold.

 

 So for a given amount of water in the air, the lower the air temperature the higher the humidity.

 

You should not have taken the dehumidifier out when you turned on the AC.

 

 

It doesn't make sense because the dehumidifier does not lower temperature. In fact, it actually increases the temperature ever so slightly as the radiator discharges heat in the room.

 

When I removed the dehumidifier and there was still far above 50% RH in the air, turning on the AC to it's lowest setting should have only further decreased the humidity. The AC has to do de humidification to work... It's passing air over cooled coils and creating evaporation that is supposed to be piped outside. All of the cold air sent in by the AC should be dehumidified, so if the RH is rising while the AC is cooling the room, then it's not doing its job properly.

 

 

2 hours ago, Stevemercer said:

The wet season will wind up over the next few weeks and the relative humidity will be well below 50% by the end of October. Maybe you can hang on a few more weeks and see if things improve then.

 

Of course, you will have the same problems in the next wet season, but maybe you will have enough time to research and work out a solution. At the very least you will be able to see if there re some rectifiable design or maintenance issues that keep the house above the outside humidity.

I'm hoping so...

 

 

2 hours ago, natway09 said:

If your aircon if working correctly & the cold pipes through your condensor unit are clear of gunk you are automatically dehumidifying 

& the drain should be trickling constantly until room is recycling already dehumidified air at which time the trickle will become less.

Try with one aircon in a closed room for 4 hours with thermostat set at 23 D. If an independent trermometer says temperature reached after this time & still humidity showing more than 55 % then you have other problems (maybe major air leakage)

If the whole house has rising damp it will take aircons weeks to dry it out (Do you have a sour smell in the house ?

 

I agree with you. Although I haven't conducted this test with the thermostat set at 23, this morning I did it with the thermostat set to 16. After about 4 hours, RH went down from 77 to 60, however temperature only reached 24.5. The AC has a bonus of a tower fan helping it circulate the air and still did not achieve near target temperature or humidity. I'll repeat the test tomorrow at 23, but I suspect it will be even less effective when I do that setting.

 

 

1 hour ago, CGW said:

Perfectly normal levels! 

 

I have a humidity meter in my office and have been watching it for many years!

A lot depends on outside humidity, in the wet season, your always going to have high readings inside, unless the room is sealed, I have double glazing, house is reasonably sealed, the reading right now, with AC on 26° is 77% as it is raining out side (Finally! ???? )

 

You have to run the AC at a lower temperature than ambient for the air to be dehumidified, it wont do anything if the compressor isn't running, also I would guess you have sliding windows? they will not help, as no seal whatsoever.

 

Yes, the room in question has sliding windows that lead to the balcony.

 

I'm glad someone else is showing high readings like that indoors, and maybe that is what I was looking for... If other people are showing above 70 humidity all the time at room temperature, maybe I will just be stuck at abnormal level unless I run dehumidifiers and run the AC cold as ice all the time.

 

What gets me though is that it doesn't seem to effect everyone here. Some people are getting normal readings without any extra effort.

 

Also, the one thing I don't understand is how exactly the humidity is reaching levels far above outside level with the AC running. For example, I went to sleep last night with humidity in my room at around 60ish... after running the AC at it's lowest setting. I turned the AC to 27 before bed and woke up to humidity of nearly 80. The AC maintained my 27 temp fine but

 

Outside RH was only 62 and temperature 32, so the compressor must have kicked in several times throughout the night.

 

I get the compressor would stop dehumidifying when it reaches target temperature but...why the moisture build up? The only source of moisture would be my body sweat and maybe the water in the toilet of the adjacent bathroom (door closed). At worst case scenerio, I would think the RH would be identical to that outside, but with some work from the compressor, shouldn't it be a bit lower? How is it getting higher with AC cooled air?

 

Also 77 humidity is deep within mold growth territory and nobody wants to sleep with their AC set to its lowest setting all throughout the night. How is it that dehumidifiers are relatively uncommon here if indoor humidity is that hard to control? It may be that people here simply do not care about mold and moisture or that there is not enough English language resources regarding humidity control in Bangkok. I'm not sure.

[DogNo1]

Allergy to mildew and mold is a big problem for me too.  I have bought an expensive UVC air filter and a dehumidifier for my bedroom to which my bathroom is connected.  I can’t manage to keep the humidity much under 62%.  To kill the mildew on the bedclothes and carpet, I spray with colorless isopropyl alcohol that I buy at a store in Sathorn.  It evaporates leaving no residual smell.  My hotel room has many sliding windows so I’m never going to get the humidity below 50%.  The problem here is not as bad as in Japan where my wooden house is built over a concrete slab but I’m moving out of it soon.  If anyone is interested in buying the 100% isopropyl alcohol, I can PM the name and phone number of my supplier.

 

Incidentally, a problem often overlooked is dust and mold that builds up on the fan of the indoor part of the unit.

[dia1]

46 minutes ago, Bender Rodriguez said:

wrong country if you don't like humidity ?  my meter says 80 percent or more, all the time

 

80% all the time? That's nuts and again far greater than the outside humidity. I suspect you have a moisture issue as well or a faulty AC. RH at that level aint healthy.

[farang51]

12 minutes ago, dia1 said:

Temperature doesn't change the amount of humidity in the air... only the relatively humidity.

That is correct. However, it is a high relative humidity that makes fungus and mold grow; thus, it is the relative humidity that is important in your case.

[johng]

Sat here at my computer desk @15.17 with just a fan  no aircon all windows and doors open temperature says 34C  RH around 57%

no mould or fungus to report ????

[CGW]

1 hour ago, dia1 said:

Outside RH was only 62 and temperature 32, so the compressor must have kicked in several times throughout the night.

Humidity will rise if the AC stops working as the ambient temp changes, I run AC at a lower temp during the cool season to keep humidity down during the cool season, where are you that it is 32°c in the morning? I would guess it is far lower than that.

[CGW]

3 minutes ago, johng said:

Sat here at my computer desk @15.17 with just a fan  no aircon all windows and doors open temperature says 34C  RH around 57%

no mould or fungus to report ????

All I can say about that is you don't live anywhere near me! ???? 

[sometimewoodworker]

55 minutes ago, dia1 said:

4 hours ago, sometimewoodworker said:

t makes complete sense. Humidity is a measure of the ability to hold water vapour in the air. The higher the air temperature the greater the amount of water it can hold.

 

 So for a given amount of water in the air, the lower the air temperature the higher the humidity.

 

You should not have taken the dehumidifier out when you turned on the AC.

 

 

It doesn't make sense because the dehumidifier does not lower temperature. In fact, it actually increases the temperature ever so slightly as the radiator discharges heat in the room.

 

When I removed the dehumidifier and there was still far above 50% RH in the air, turning on the AC to it's lowest setting should have only further decreased the humidity. The AC has to do de humidification to work... It's passing air over cooled coils and creating evaporation that is supposed to be piped outside. All of the cold air sent in by the AC should be dehumidified, so if the RH is rising while the AC is cooling the room, then it's not doing its job properly.

 

Please re-read my posting. 
 

I did not say that the dehumidifier lowered the room temperature.

 

Since I have the one I posted (it’s running right now!) I do understand how they work.

 

You seem to not understand what I said.

 

Relative Humidity is directly related to temperature.

a sealed room with a humidity of 100% and temperature of 20C will have a much lower RH when the temperature is raised to 35C of about 45%

 

So your AC is not extracting enough water when cooling the room to maintain the RH

 

Old A/C so failing, clogged outlet pipe, outlet pipe too small, A/C drainage fault, A/C too big for the room it is in, dirty A/C. are all possible causes 

[sometimewoodworker]

31 minutes ago, CGW said:

Humidity will rise if the AC stops working as the ambient temp changes, I run AC at a lower temp during the cool season to keep humidity down during the cool season, where are you that it is 32°c in the morning? I would guess it is far lower than that.

Absolutely wrong (unless you are using a heat pump AC in heating mode.)
The relationship between RH and temperature is that a rise in temperature gives a drop in humidity.

 

if your RH is 60% and temperature is 20C the water is 10.4g/m³ the dew point is at 12C

Turn off the AC and increase the temperature to 30C the RH will drop to about 35% the dew point remains at 12C 

AbsoluteHumidityTable.pdf

[johng]

55 minutes ago, CGW said:

All I can say about that is you don't live anywhere near me! ???? 

Perhaps we are both glad about that ????

[xtrnuno41]

The airco's cant cope, all is new. So maybe the capacity is too low?

Maybe as said the condens drain pipes are clogged, where do they go to? Do they drain the condens somewhere outside, or did they forget?

Maybe there is not enough cooling fluid in the system? Yha ,ok i know they are new. 

Where is the compressor unit installed? In the sun? I think it can affect the capacity, it gets heated also by the sun. It needs to get rit of the heat of the cooling fluid and the heat of the sun.

An open door or gaps brings in new hot moisturized air and your ac keeps running, but cant cope.

your house is built with no block of moist from ground, the walls can suck up water and all keeps moist. Maybe a leakage in water supply or a drain? 

[CLW]

Your room has probably so many air leaks. Thai building and quality standards are light-years away from European or western standards.

Just to give you an example, since about 10 years every new building in Germany must pass a so-called blower door test.

In the entrance door they install a blower fan with pressure sensor and it can not fail a certain level of air tightness of the whole building. Another example, the kitchen fume cupboard must have a reed sensor with the next window in order to work (the window must be tilt open in order to switch on the fume fan).

 

As others suggested, buy a good air purifier with UV and/or ozone treatment to kill fungus and spores in the air.

Clean your air-con regularly, buy a vacuum cleaner with HEPA filter

[CGW]

1 hour ago, sometimewoodworker said:

The relationship between RH and temperature is that a rise in temperature gives a drop in humidity.

Yes, I get what you are stating, I was wrong!

I struggle to explain exactly what I mean with mere words, for some reason its a confusing subject, maybe this C&P explains better what I mean. (maybe not!)

 

"However, relative humidity is dependent on air temperature, too. If the water vapor content stays the same and the temperature drops, the relative humidity increases. If the water vapor content stays the same and the temperature rises, the relative humidity decreases. This is because colder air doesn’t require as much moisture to become saturated as warmer air. "

"Since warm air is less dense than cold air, there is more room for water vapor in warm summer air as compared with cold winter air."

[impulse]

6 hours ago, sometimewoodworker said:

You should not have taken the dehumidifier out when you turned on the AC.

 

Winner, winner, chicken dinner.

 

Also, if the A/C is oversized, it won't pull enough humidity out of the air before the room is cool enough that the A/C cycles off by the thermostat.  You want an A/C that runs most of the time.  Not one that only runs a few hours a day.  This is one case where you don't want to send a man in to do a boy's job.  Keeping the dehumidifiers on will help if the A/C's aren't pulling enough moisture on their own.

 

The OP may also want to look into Tea Tree Oil.  We used it offshore to reduce the mold and mildew inherent in an overtaxed A/C system.  It's controversial, but some folks swear by it.  I'm allergic to mold, mildew and everything that grows in the tropics and it helped my allergies when I lived in BKK.

 

[farang51]

44 minutes ago, CGW said:

Yes, I get what you are stating, I was wrong!

I struggle to explain exactly what I mean with mere words, for some reason its a confusing subject,

It is a confusing subject; and looking for clarity on various websites may not make it easier. I have been looking at a few websites to find an easy to understand explanation of humidity vs relative humidity to post here; and some of them start by telling the difference - and then in the next paragraph they write "humidity" when they clearly mean "relative humidity".

[RocketDog]

6 hours ago, Lacessit said:

A 5% copper sulphate solution is very effective against mold and fungus. Spray on, wipe off with damp cloths after 24 hours. No smell.

How old is the house? If it's more than 15 yo, given some Thai builders, it's probably leaking like a sieve.

If the OP is renting, simplest solution is move.

Copper sulfate is available on Lazada. I recently bought some and it's also good for killing roots in drainage pipes. 

I bought it to grow very cool large blue crystals! 

[johng]

7 minutes ago, RocketDog said:

I bought it to grow very cool large blue crystals!

What chemical to use to grow some green Kryptonite crystals ?

[RocketDog]

In cold climates a layer of thin plastic sheeting (visqueen) is put in the attic directly above the ceiling under the insulation to prevent room humidity from condensing in the cold insulation in winter. 

 

The point is that it prevents water vapor transmission. If possible put a layer in your attic which will prevent humid air migration into the room. Can't do much about the walls but if they're concrete they won't pass moisture very fast. 

 

This advice may not help if you're renting or can't get into the attic. But I agree with the others on this thread. Running the aircon should take lots of water out of the air of a sealed room. You should see a small constant trickle of water out of the aircon until the air dries out.

 

Even cheap dehumidifiers should put a dent in the Rh of a closed room. It seems that we're missing a large variable here somewhere. Are you sure your Rh measurement instrument is accurate for instance? 

 

Your breath and body of course create humidity but it's a minor source unless you're hosting large orgies in the room. 

[RocketDog]

16 minutes ago, johng said:

What chemical to use to grow some green Kryptonite crystals ?

Sorry, but that's classified info. Only me and Lex Luthor know that and we ain't sayin'. 

[dia1]

Well after days of constant dehumidifying and being unsure why the RH was not dropping down to reasonable levels, the problem finally showed itself. Last night during a heavy rain, the small invisible leak finally sprang into a massive leak. Looks like both a leak in the ceiling and a leak on a wall effecting three floors. I was about to throw my hands up and cough it up to "Thai humidity" but the data simply didn't add up.

 

RH should always drop when running the AC at a setting lower than the current temperature, unless there is a source of moisture entering the room and if a 2L electric dehumidifier or a AC running for hours on its lowest setting cannot bring humidity down below 50, there is almost always something weird going on.

 

I suspect there are other issues like ventilation or dirty coils on the ACs as well, but the 80+ humidity was water intrusion.

 

IMO, your home should never have a RH much higher than outside, especially if you're running an AC. Maybe temporarily after taking a shower or cooking, but otherwise there is no reason for that much moisture to enter the room. Yes, RH will rise as the temperature drops, but if the temperature is dropping due to AC cooling, the AC is removing moisture to achieve that effect, so RH should be at outside levels or lower. Once you are hitting constant RH above outside level, something in the house is broken. Or rising damp...

 

I really wish this had been all for nothing, but looks like I have a much bigger problem on my hands.????

[moontang]

A unit that is too big will cause condensation on the windows.  My humidity on a high floor is currently 44%, and I just took a hot shower 4 meters away.  Temp 26.1 but I take temp on opposite side of the room at two meters high.

[Cod Face]

On 9/30/2020 at 12:28 PM, dia1 said:

Thai doctor recommended using a dehumidifier if the humidity in the house is above 50%.

...I bought two 2L tank humidifiers...

"...I bought two 2L tank humidifiers..."

Maybe you should have bought dehumidifiers?

[dia1]

On 10/2/2020 at 3:51 PM, Cod Face said:

"...I bought two 2L tank humidifiers..."

Maybe you should have bought dehumidifiers?

That was a typo... I bought two dehumidifiers. I didn't bother to correct, since everyone else seemed to know what I meant.

[Don Chance]

I have mold allergies and i can tell you Thailand is a very difficult place.

In my experience the mold problem is always coming from underneath the tiles. The slab gets wet or the balcony gets wet and the water penetrates the tiles and saturates the concrete slab. So there is dampness and water under neath your tiles if you could look. That is where the mold grows and probably started the day they build the place because the slab was wet.

 

Can a dehumidifier correct this? Maybe but as you have noticed they are not that effective. There is something called an industrial dehumidifier used by contractors which cost about 600-1800$ and it will bring the humidity down.

 

The best solution is remove the tiles and have a bare floor with carpet or it can be painted or sealed in the dry season. There are a few guesthouse like this.

You will also get mold in concrete forms too. The best bet is probably a raised bungalow made from wood or wood and concrete. Try another apartment. Watch out for sewer tanks under your unit this will great some toxic mold.

Vietnam was better building. Problem in Thailand they are clueless about the proper way to install tiles or sewage or many things...

[moontang]

9 hours ago, Don Chance said:

I have mold allergies and i can tell you Thailand is a very difficult place.

In my experience the mold problem is always coming from underneath the tiles. The slab gets wet or the balcony gets wet and the water penetrates the tiles and saturates the concrete slab. So there is dampness and water under neath your tiles if you could look. That is where the mold grows and probably started the day they build the place because the slab was wet.

 

Can a dehumidifier correct this? Maybe but as you have noticed they are not that effective. There is something called an industrial dehumidifier used by contractors which cost about 600-1800$ and it will bring the humidity down.

 

The best solution is remove the tiles and have a bare floor with carpet or it can be painted or sealed in the dry season. There are a few guesthouse like this.

You will also get mold in concrete forms too. The best bet is probably a raised bungalow made from wood or wood and concrete. Try another apartment. Watch out for sewer tanks under your unit this will great some toxic mold.

Vietnam was better building. Problem in Thailand they are clueless about the proper way to install tiles or sewage or many things...

Crawl spaces are a huge contributor to household air contaminants.  https://crawlspace.com/

[Don Chance]

8 hours ago, moontang said:

Crawl spaces are a huge contributor to household air contaminants.

I don't think i've seen a bungalow with a crawl space in Thailand. Mostly it on slab or on piers.

The traditional way to build in Thailand is on piers, it still makes sense today. On slab is just a cheap and lazy way. A slab would need to have a water barrier between the ground and slab, rubber or foam.

[moontang]

45 minutes ago, Don Chance said:

I don't think i've seen a bungalow with a crawl space in Thailand. Mostly it on slab or on piers.

The traditional way to build in Thailand is on piers, it still makes sense today. On slab is just a cheap and lazy way. A slab would need to have a water barrier between the ground and slab, rubber or foam.

So wrong. Torn up floors in CM to install proper toilets, and a friend built 13 houses at 10 million each in hua hin...none on slab.  Crawl space is done in humid areas of the South (USA), anyplace else it is slab, since the 40s.  Building on terrible soil is a crapshoot.