What is the cheapest method of dehumidifying a room, long-term?

[Tapster]

Hi

I'm concerned to see that mildew is starting to affect fabric materials in my home.

I'm assuming that this must be due to high humidity and poor ventilation. I live in Phuket.

I am sure that air conditioning, set on the "dehumidify" setting will be a very expensive long-term solution, so can anyone advise me please, on the cheapest dehumidifying methods for making a permanent change in the atmosphere in the house?

For instance, opening all the windows will increase ventilation but it will also fill the house with humid air, so there's a conflict there.

Bulk silica gel?

Calcium chloride?

A mystery Thai solution?

Help, please!!!

[jvs]

Ventilation,fresh air flow is what you want.Still standing air can grow all kind of nastys.Make sure there are open windows or doors opposite each other so air can flow.

Maybe also a vent in the roof would help,does not need to be costly.

[manarak]

depending on size of the room(s), airconditioning can be a viable method.

[lopburi3]

Thai answer is do not use fabrics in closed rooms. This is a humid land so if air conditioning to keep humidity down is not an option it is best not to use cold weather stuffed furniture, rugs and closed closets.

[impulse]

Lopburi has the best solution (#4), but a dedicated dehumidifier uses a lot less power than air conditioning.

They aren't cheap at around 10,000 baht (and up), so it becomes a payout calculation if you have A/C anyway. In the US, they can be purchased for about $150 and the decision is a lot easier... I used a couple in the family lakeside Texas home I stayed at a few months a year when I lived in Asia.

[lopburi3]

Actually they do not operate for free (almost as much power as air conditioner) - and you have the added heat that they are not expelling from your living area and the need to empty bucket. In cooler areas they have a value - not so much so in Thailand where you really also need cooling at the same time.

[impulse]

Actually they do not operate for free (almost as much power as air conditioner) - and you have the added heat that they are not expelling from your living area and the need to empty bucket. In cooler areas they have a value - not so much so in Thailand where you really also need cooling at the same time.

True about the power, but nowhere near what the A/C used. More like a refrigerator- which has a very similar operating principle, and the same problems with waste heat. They also had an adjustment that turned them on and off as the humidity changed.

I got the ones with a hose on the back so they drained themselves. (Though I occasionally captured the distilled water for general uses like the car batteries)

And for the months at a time nobody was using the house, I didn't care how hot it got (within operating limits)- it would be different if I came home at night. Though I must say it never got very hot and always felt pretty comfortable coming in from the muggy humidity, even if the temperature was a little higher.

Edited July 19, 2015 by impulse

[sdanielmcev]

Circulating air, like a fan, is the cheapest solution, and not necessary to open windows. One of the things I always tell people about water/ moisture is if the product can't stand the moisture in your home, get rid of it.

[Gumballl]

I never understood the adversion to using the air-con. I live in a 1250 sq. foot house (sorry, I can't be bothered to convert that to sq. meter), and I run two a/c units 24x7. The cost is about 2000 baht per month, which is not that bad. My place stays dry, I stay dry, and I'm happy.

[4evermaat]

I never understood the adversion to using the air-con. I live in a 1250 sq. foot house (sorry, I can't be bothered to convert that to sq. meter), and I run two a/c units 24x7. The cost is about 2000 baht per month, which is not that bad. My place stays dry, I stay dry, and I'm happy.

Are you sure about that? What are the BTU size of your a/c units? Are they both on the same floor? Are you under any shaded area or no direct sunlight to these rooms? Single story or 2 story house?

That's very impressive to have 2 units running continuously and you only pay 2000 baht. Did you mean 2k each room?

[Tapster]

Many thanks for all the comments.

This is my understanding so far, and please help with my final queries below, thanks.

Mildew and dampness-nasties won't be a problem if:

• you have the right fabrics and sufficient ventilation,
  
  or
  
• you use dehumidifiers or aircon and are willing to pay for the extra electricity
  
  
  

​However, in my case:

• We've just spent a king's ransom shipping all our stuff from South Africa. Yes, it was a choice but this is the situation and we're not going to get rid of our stuff.
  
• So, we have the wrong fabrics.
  
• Having spent the aforementioned king's ransom, we'd rather not have to use our aircon 24/7, which for the whole house would mean 2-3 units minimum.
  
  
  

So, my further queries, please:

• Can opening all the windows, all the time, stop the problem, even with unsuitable fabrics?
  
  (Obviously the house would be hot, and at the same humidity % as the air outdoors. But we have ceiling fans and aircon to make specific areas more comfortable)
  
• Is there no cheap alternative that anyone's heard of, involving keeping rooms closed and using a chemical dehumidifier?
  
  (There are commercial versions, holding hygroscopic crystals in a plastic case of some sort, but these are expensive if used 24/7. I'm wondering if, for instance, Calcium Chloride {used in swimming pools} might work, or maybe silica gel is available cheaply?)
  
  https://en.wikipedia.org/wiki/Desiccant

Any advice will be useful, thanks.

​

[Gumballl]

I never understood the adversion to using the air-con. I live in a 1250 sq. foot house (sorry, I can't be bothered to convert that to sq. meter), and I run two a/c units 24x7. The cost is about 2000 baht per month, which is not that bad. My place stays dry, I stay dry, and I'm happy.

Are you sure about that? What are the BTU size of your a/c units? Are they both on the same floor? Are you under any shaded area or no direct sunlight to these rooms? Single story or 2 story house?

That's very impressive to have 2 units running continuously and you only pay 2000 baht. Did you mean 2k each room?

The 2K figure was based on the cost during my last (3 week) visit to LOS, which was 2 years ago. I will need to see what it is now. As for the home, it is a single story. When I get a chance, I will ask my wife for additional details.

P.S. My wife never nags me about the cost of running the A/C units all day long, so as I stated earlier, the cost is really no big deal. As for the BTU size, I have no idea... I simply picked out two units that are manufactured by Sharp and measure about 1 meter (or thereabouts) in width.

Edited July 20, 2015 by Gumballl

[Naam]

Is there no cheap alternative that anyone's heard of, involving keeping rooms closed and using a chemical dehumidifier?

no mate, there isn't

[WitawatWatawit]

I spray my heavy use fabrics with Scotchguard - settees, chairs. Never noticed any mildew problems as the years have gone by.

[Gumballl]

Many thanks for all the comments.

This is my understanding so far, and please help with my final queries below, thanks.

Mildew and dampness-nasties won't be a problem if:

• you have the right fabrics and sufficient ventilation,

  or

• you use dehumidifiers or aircon and are willing to pay for the extra electricity

​However, in my case:

• We've just spent a king's ransom shipping all our stuff from South Africa. Yes, it was a choice but this is the situation and we're not going to get rid of our stuff.

• So, we have the wrong fabrics.

• Having spent the aforementioned king's ransom, we'd rather not have to use our aircon 24/7, which for the whole house would mean 2-3 units minimum.

So, my further queries, please:

• Can opening all the windows, all the time, stop the problem, even with unsuitable fabrics?

  (Obviously the house would be hot, and at the same humidity % as the air outdoors. But we have ceiling fans and aircon to make specific areas more comfortable)

• Is there no cheap alternative that anyone's heard of, involving keeping rooms closed and using a chemical dehumidifier?

  (There are commercial versions, holding hygroscopic crystals in a plastic case of some sort, but these are expensive if used 24/7. I'm wondering if, for instance, Calcium Chloride {used in swimming pools} might work, or maybe silica gel is available cheaply?)

  https://en.wikipedia.org/wiki/Desiccant

Any advice will be useful, thanks.

​

My advice would have been to experience the difference between living in a dry climate versus living in a hot/humid one.

I've lived in both in the US... Florida and California. In California, it was practically unheard of to have air-conditioning in homes that reside near the coast line, simply because there was rarely a need for such. The only time air-con would have been nice is when the Santa Ana winds were blowing the heat from the desert to the coast.

In Florida, as it is where I live now (in Maryland), a/c is necessary 24x7 during the summer months. You can choose to live like a Thai native, and brush off the fact that the country is one degree way from the heat of hell, but I for one would rather live in comfort.

If your main goal is to remove humidity from the air (without too much regard to the temperature in the room), then I would suggest that you run your a/c units at 25-26 C during the summer months (i.e. from April-October). To seek relief from the heat, using ceiling or floor fans.

[jmccarty]

If you have reasonably high ceilings and long stemmed ceiling fans running counter-clockwise, it draws air up and out open windows and doors. If you have screens, this could be the lowest cost means of keeping humidity low. Much depends on the size of your rooms, what other humidity generating things are in the rooms. But AC is by far the most expensive general option.

[Craig krup]

The basic question is, "How much water vapour is suspended in the air that you're introducing?" If the stuff you're bringing in is as loaded with water as the stuff you've got then ventilation won't make a blind bit of difference, unless you think that fresh air will kill nascent bug colonies. I don't think it will. I think keeping things folded, and fetid as hell, will make it worse, but in and of itself new wet air isn't going to be much better than old wet air. What will kill a lot of the bugs that grow is direct sunlight, so hauling what's most affected outside and hanging it up to bake might help. Concentrating the stuff most affected in a small room with AC would preserve it at low cost, if you can't bear to either chuck it or dehumidify everything.

[jmccarty]

This company has some other solutions: http://www.passivent.com/index.html

Look reasonable.

[Naam]

This company has some other solutions: http://www.passivent.com/index.html

Look reasonable.

unfortunately not applicable in a tropical country with a rainy season.

[Naam]

If you have reasonably high ceilings and long stemmed ceiling fans running counter-clockwise, it draws air up and out open windows and doors. If you have screens, this could be the lowest cost means of keeping humidity low. Much depends on the size of your rooms, what other humidity generating things are in the rooms. But AC is by far the most expensive general option.

when the ambient outside humidity is high, e.g. near the beach or during the rainy season, dehumidifying by consuming energy is the only feasible option.

[1BADDAT]

If you have reasonably high ceilings and long stemmed ceiling fans running counter-clockwise, it draws air up and out open windows and doors. If you have screens, this could be the lowest cost means of keeping humidity low. Much depends on the size of your rooms, what other humidity generating things are in the rooms. But AC is by far the most expensive general option.

when the ambient outside humidity is high, e.g. near the beach or during the rainy season, dehumidifying by consuming energy is the only feasible option.

Don't try to use logic or laws of physics with these people. A fan is a magical device that runs with no electrical cost and instantly reduces the temperature and humidity. People that use air conditioning are high on drugs and enjoy throwing money away.

[1BADDAT]

I never understood the adversion to using the air-con. I live in a 1250 sq. foot house (sorry, I can't be bothered to convert that to sq. meter), and I run two a/c units 24x7. The cost is about 2000 baht per month, which is not that bad. My place stays dry, I stay dry, and I'm happy.

Are you sure about that? What are the BTU size of your a/c units? Are they both on the same floor? Are you under any shaded area or no direct sunlight to these rooms? Single story or 2 story house?

That's very impressive to have 2 units running continuously and you only pay 2000 baht. Did you mean 2k each room?

The thing that uses the most energy is the compressor. He cold run them at 27C 24/7 and the compressor would hardly ever kick on. And the other really important consideration is insulation.

[Naam]

Don't try to use logic or laws of physics with these people. A fan is a magical device that runs with no electrical cost and instantly reduces the temperature and humidity. People that use air conditioning are high on drugs and enjoy throwing money away.

[StreetCowboy]

If you have reasonably high ceilings and long stemmed ceiling fans running counter-clockwise, it draws air up and out open windows and doors. If you have screens, this could be the lowest cost means of keeping humidity low. Much depends on the size of your rooms, what other humidity generating things are in the rooms. But AC is by far the most expensive general option.

when the ambient outside humidity is high, e.g. near the beach or during the rainy season, dehumidifying by consuming energy is the only feasible option.

I think a dehumidifier will work better (cheaper) than an air con on dehumidify, though, because the dehumidifier dumps its heat into the room, raising the temperature and thus lowering the relative humidity, while the air con dumps its heat outside, effectively cooling the room a little bit.

I sweat like a horse, and high temperatures don't bother me as much as high humidity.

Currently, I live on a high floor, and I never use the air con except when I have guests staying, and need to close the doors for privacy and discretion, thus losing the through-breeze. I do have the fan running all the time, to keep the air moving, and wafting away the evaporating sweat

SC

[Tapster]

Thanks for the interesting discussion.

I want a cheap solution and so I've been researching the use of desiccants in commercial and household applications and there's definitely a place for various media, the cheapest of which are Calcium Chloride and silica gel.

I can get 25kg of CaCl2 for 800 THB (and possibly less if I try) and I can get bulk silica gel for 150 THB/kg.

Both very effectively remove water from the air.

Both are reuseable, by heating to remove the adsorbed water.

CaCl2 removes more water per unit volume than does silica gel BUT the resulting solution is highly corrosive to metals and the vapour affects things in the vicinity.

Silica gel is inert, virtually non-toxic unless you spoon it into your mouth, and the type I'm getting has a gradual colour change from orange to green which indicates its degree of saturation.

I reckon I'm going to try leaving a few 1kg containers of this stuff in out-of-the-way places in the affected rooms and just see what happens.

I can get a cheap digital humidity meter from Lazada for 226 THB.

The experiment begins!

Any thoughts?

[impulse]

The experiment begins!

Any thoughts?

Post back with your results!

And keep in mind you may have to regenerate the media a few times as it wicks moisture out of every porous surface in your house. Hopefully, once you get the humidity down (and keep the room sealed), it will stay down.

But keep in mind- breathing, cooking, bathing , all add moisture to the air- more than I would have thought

[Beetlejuice]

We never have humidity problems in our house, I solved all that long ago.

In our living room, which is most important because we spend most of our time there, I installed 3 x16inch wall fans and installed 2 extractor fans in the external wall. Very cheap to run with virtually no maintenance.

We always leave our windows open during the hot months as I`m a stickler for free flowing fresh air. Hate being trapped in an artificial environment with air con.. My systems operate by air coming in via the windows, is circulated by the fans and then sucked out by the extractors, which is a continuous flowing process. Total estimated electric bill for running the fans and extractors about 15 hours per day, every day except for the colder months of November and February here in Chiang Mai is 500 baht per month.

. .

[MAJIC]

If you have reasonably high ceilings and long stemmed ceiling fans running counter-clockwise, it draws air up and out open windows and doors. If you have screens, this could be the lowest cost means of keeping humidity low. Much depends on the size of your rooms, what other humidity generating things are in the rooms. But AC is by far the most expensive general option.

when the ambient outside humidity is high, e.g. near the beach or during the rainy season, dehumidifying by consuming energy is the only feasible option.

Dehumidifying is only solution to the dreaded Black mold,when you see it in your bathrooms and other damp places,you not only have a damp problem, but also a health problem, from airborn spoors from the black mold

[Naam]

CaCl2 removes more water per unit volume than does silica gel BUT the resulting solution is highly corrosive to metals and the vapour affects things in the vicinity.

there's another caveat which you should take into consideration. the efficiency of both drying agents depends on its surface exposure. that means it won't be easy to find enough space in "out-of-the-way places" to spread it as much as possible. as far as the use of CaCl² is concerned i pity your door handles, hinges and any metal components nearby. but the efficiency of dehydrated CaCl² is 10-12 higher than Silica Gel.

it's worth a try but i predict you will be disappointed.

[lopburi3]

You are not the only resident - consider the effects on all.