Whole House Fan

[BillyBobThai]

I am in the process of buying a house in Chiang Mai and want to install a whole house fan for cooling at night. I have used these fans back in the states for 60 years and they work great if used at night when the temperature has dropped below the temp. inside of the house. Having never used one in a house than is solid brick and concrete, I am hopping that by running the fan for 6 to 10 hours a night, that I can cool down the house at night, and not have to use the A/C much, if any, in the day. These fans move 5,000 cfm to

10,000 cfm, and exchange the full volume of air in the house every few minutes using a 1/3 hp motor.

My question, does anyone here in CNX have any experience with one here??

Thanks

[Diablo Bob]

Interesting, used in conjunction with a roof rotary vent (cyclone) you might see good results. The main problem here in Thailand is a lack of insulation above the ceiling. The sun heats the air in this attic space and it just sits there all night long. Evacuate this heated air with the cyclone and replace it with cooler air with your little system might be the trick.

[elektrified]

I had ceiling fans along with the rotary vents in my home in Los Angeles. But I can't see how they would work in brick and concrete homes in Thailand.

[Diablo Bob]

I had ceiling fans along with the rotary vents in my home in Los Angeles. But I can't see how they would work in brick and concrete homes in Thailand.

I don't see where being a brick or concrete home makes a difference in how a rotary vent works...... the vent works on the convection currents developed by hot air rising. Now if you are alluding to the fact that a concrete/brick home is a heat sink, that is another question, but nothing to do with a rotary vent.

[NancyL]

A good Thai innovation that you might want to consider is putting water sprinklers on the roof to cool it down. These seem to make a dramatic difference in the daytime temperatures within structures.

[BillyBobThai]

My intent is to install a rotary cyclone vent on the roof, to vent the roof during the day, and to allow the whole house fan a way for the air to escape. My other idea is to add 4 inch fiberglass, foil covered insulation to the top of the ceilings. Yes the whole house is a massive heat sink, and if I can lower the temperature a little each day, the A/C will not have to be used as much.

Edited June 28, 2011 by BillyBobThai

[Diablo Bob]

My intent is to install a rotary cyclone vent on the roof, to vent the roof during the day, and to allow the whole house fan a way for the air to escape. My other idea is to add 4 inch fiberglass, foil covered insulation to the top of the ceilings. Yes the whole house is a massive heat sink, and if I can lower the temperature a little each day, the A/C will not have to be used as much.

Plant trees for shade, very effective. How high is the ceiling in the house that you are purchasing? The higher the ceiling the better!

Another little trick that does work efficiently around 6 months a year is evaporative cooling, but as the humidity rises, the cooling effect drops off.

Nancy has a great idea, consider a misting system. If you are moving that volume of air through the house, a mistng system would be a very effective method of transforming your house into a giant evaporative cooler....

[BarnicaleBob]

I think you have a good idea there and should go ahead and do it. I owned a brick home in Florida which has about the same climate as Chiang Mai, I installed a whole house fan and it worked very well for me there so I see no reason for it not to work for you here.

Edited June 28, 2011 by BarnicaleBob

[CMX]

I'm sure that I am not alone in doing this on a small scale. That is, whenever the night-time temperature is likely to drop below the inside temp, I use two standing fans as exhaust fans and draw in outside air overnight. I even have concluded, on many mornings, that it helps quite a bit.

The trouble for the purposes of comparison, of course, is that the outer walls of homes here have no insulation qualities. That is, one looses the advantage to the outside ambient air much more quickly than in insulated homes (no termites in the walls, however). Obviously, shade helps here as it does always, but the walls might as well be porous.

So I'd suppose that the savings are more difficult to figure compared the costs of installation and reduced use of aircon, though I cannot imagine that the project would not be worthwhile in the long run.

[Naam]

besides roof ventilation an ideal addition to save on aircon energy is a "whole house fan". in a fully airconditioned home where slow cross ventilation is abhored (like mine) a powerful fan is used for a short time during the cooler hours to supply fresh air to the house. in the cooler months november till february i am cooling down the whole house (except the airconditioned master-bedroom where Mrs Naam sleeps late because she is a night owl) with the outside ambient temperature by running the fan from 04.00hrs till 07.00hrs. reason for the rather long runtime is that not only the inside air is replaced by cool air but floors and walls too (which is important).

Edited June 29, 2011 by Naam

[slapout]

The problem I can foresee with this system/fan here in Thailand is the windows, which are a important part of the air circulation. The mentioned system works good with windows which raise up to open, as you can adjust the inflow of air in each room. This type window is normally level with the bed, thus air flow across those sleeping.

We never tried to ventilate the whole house, just 4 bedrooms closed off from the rest of the house. Each bedroom had a window open about 3 to 4 inches and the larger mention unit (10,000cfm) worked fine.

[Spoonman]

These fans move 5,000 cfm to 10,000 cfm, and exchange the full volume of air in the house every few minutes using a 1/3 hp motor.

What sort of noise is involved in the transfer of such volumes of air ?

[Naam]

These fans move 5,000 cfm to 10,000 cfm, and exchange the full volume of air in the house every few minutes using a 1/3 hp motor.

What sort of noise is involved in the transfer of such volumes of air ?

a lot of noise. usable during "sleeping" times only in big homes.

[Naam]

The problem I can foresee with this system/fan here in Thailand is the windows, which are a important part of the air circulation. The mentioned system works good with windows which raise up to open, as you can adjust the inflow of air in each room. This type window is normally level with the bed, thus air flow across those sleeping.

We never tried to ventilate the whole house, just 4 bedrooms closed off from the rest of the house. Each bedroom had a window open about 3 to 4 inches and the larger mention unit (10,000cfm) worked fine.

quite an inefficient use of a whole-house fan. but then... to each his own.

[slapout]

The system I am familiar with was surprising quiet. It had the auto louver mounted in the ceiling and the fan was in the attic directly above the louvers. The closer bedroom door (open when operating) was about 10 foot from the system. I would equate the sound level to a free standing fan in the room.

[slapout]

Naam: not sure that the system we had, would have pulled the volume of air required for the full house. A swamp cooler was used for the living, dining, kitchen areas during the daytime heat and the exhaust fan for the sleeping hours. It made for a comfortable house, even with daytime temperatures in the 40 plus range.

[Naam]

Interesting, used in conjunction with a roof rotary vent (cyclone) you might see good results. The main problem here in Thailand is a lack of insulation above the ceiling. The sun heats the air in this attic space and it just sits there all night long. Evacuate this heated air with the cyclone and replace it with cooler air with your little system might be the trick.

using the whole-house fan the "american way" by blowing the air in the attic requires a certain diameter of ridge vents to ensure unrestricted airflow. ridge vents are neither available in Thailand nor does anybody know how to install them. even a few "turbine vents" won't do the trick. you have to find a way to exhaust the air through an outside wall. not an easy task if you don't have gables but only hip roofs! it took me a few days to find a solution but it was much easier because the home wasn't built yet.

[Diablo Bob]

Interesting, used in conjunction with a roof rotary vent (cyclone) you might see good results. The main problem here in Thailand is a lack of insulation above the ceiling. The sun heats the air in this attic space and it just sits there all night long. Evacuate this heated air with the cyclone and replace it with cooler air with your little system might be the trick.

using the whole-house fan the "american way" by blowing the air in the attic requires a certain diameter of ridge vents to ensure unrestricted airflow. ridge vents are neither available in Thailand nor does anybody know how to install them. even a few "turbine vents" won't do the trick. you have to find a way to exhaust the air through an outside wall. not an easy task if you don't have gables but only hip roofs! it took me a few days to find a solution but it was much easier because the home wasn't built yet.

Good point about the ridge vents, but how about Soffit ventilation? Inasmuch as you are introducing about 5000cfm of air into this attic space, wouldn't a soffit ventilation system give you that unrestriced airflow? Just asking by the way, not trying to be argumentative.....

[Naam]

Naam: not sure that the system we had, would have pulled the volume of air required for the full house. A swamp cooler was used for the living, dining, kitchen areas during the daytime heat and the exhaust fan for the sleeping hours. It made for a comfortable house, even with daytime temperatures in the 40 plus range.

then you didn't have a 10,000 cfm fan which is noisy like an aircraft engine. 10k cfm equals >17,000 m³/h. i have a rather big home, volume ~2.300m³, my present fan capacity is 20,000m³/hour i.e. every 7 minutes a total air exchange. however it's not the air exchange i am after but cooling down floors and walls during the "cool" season which saves a couple of thousand Baht per month (from november till march) .

from april till october when the outside temperature matches or is higher than the inside temperature of our (fully airconditioned) house i just air for 10-15 minutes in the early mornings before sunrise.

[Naam]

Good point about the ridge vents, but how about Soffit ventilation? Inasmuch as you are introducing about 5000cfm of air into this attic space, wouldn't a soffit ventilation system give you that unrestriced airflow? Just asking by the way, not trying to be argumentative.....

venting through the soffit works as long as the available area is big enough and does not restrict the airflow. it shouldn't be a problem to add a few louvers and protect them with wire mesh that critters can't get into the attic.

[jaideeguy]

So, where in CM could I find a smaller unit?? I do have gable end vents as well as a couple of those spinning turbines to vent the hot air out and the turbines never stop spinning......meaning a constant passive air flow and have tested it by opening an attic pannel and watching smoke go directly up into the attic. Eventually the house cools at around 10pm with this passive system, but I would like it to cool faster.

Did the OP mention where they are available in CM?/ or could one [or a couple] of those bathroom fan vents work in a horizontal position??

[Naam]

if you have gables then you can mount them vertically. an electrically driven fan is much more efficient than the "roof turbines" which even block the hot air if not driven by a breeze. i installed a big roof fan but run it stepless with a frequency converter. overkill and much too expensive as there are solutions which cost a fraction! alas... shit happens

[Naam]

or could one [or a couple] of those bathroom fan vents work in a horizontal position??

oops! i assume you mean installing them in the soffit or the ceiling? yes you can. but make sure they are strong enough to lift the louvers when mounted horizontally!

[BillyBobThai]

The houses that I had in Atlanta had the fan mounted in the ceiling in the hall way between the bedrooms. The noise was not much different from a large floor fan running. As a child I would spend summers with my grandmother who lived 100 meters from a railroad track. You just get used to it. It is a white noise that helps to put you to sleep. All of the windows in my house were left open about 4 to 6 inches and that allowed a good breeze to flow thru. The main thing I want to do is to cool down the thermal mass that is the wall and floors at night. The house we are looking at has a hip roof which is why I am looking at a turbine vent. There is also a soffit that goes around the house where vents can be installed.

On another note, one summer we went to Salt Lake City to visit the wife's sister. She had a large swamp cooler mounted on the roof that fed into a distribution system that fed the whole house. The air coming out was cold as air coming out of an A/C. The reason was that the humidity there was less than 10%. They will not work like that here.

Forgot to mention, I saw a place that has several large fans mounted on the front of their business. I am assuming that this place sell ventelation equipment . This is on the road that past the airport on the way to Hang Dong.

It is on the right side of the road going out of CNX.

Edited June 29, 2011 by BillyBobThai

[elektrified]

Interesting, used in conjunction with a roof rotary vent (cyclone) you might see good results. The main problem here in Thailand is a lack of insulation above the ceiling. The sun heats the air in this attic space and it just sits there all night long. Evacuate this heated air with the cyclone and replace it with cooler air with your little system might be the trick.

using the whole-house fan the "american way" by blowing the air in the attic requires a certain diameter of ridge vents to ensure unrestricted airflow. ridge vents are neither available in Thailand nor does anybody know how to install them. even a few "turbine vents" won't do the trick. you have to find a way to exhaust the air through an outside wall. not an easy task if you don't have gables but only hip roofs! it took me a few days to find a solution but it was much easier because the home wasn't built yet.

That is what I forgot to mention in my post, the ridge vents.

[MauriceVanTine]

besides roof ventilation an ideal addition to save on aircon energy is a "whole house fan". in a fully airconditioned home where slow cross ventilation is abhored (like mine) a powerful fan is used for a short time during the cooler hours to supply fresh air to the house. in the cooler months november till february i am cooling down the whole house (except the airconditioned master-bedroom where Mrs Naam sleeps late because she is a night owl) with the outside ambient temperature by running the fan from 04.00hrs till 07.00hrs. reason for the rather long runtime is that not only the inside air is replaced by cool air but floors and walls too (which is important).

Naam I am very interested in installing an attic fan had them back in Texas could you tell me where I might find a fan and grattings?

W/RMoe

http://www.thaivisa....ost__p__4211217