How To Cool Rooms At Night

[dinga]

Appreciate suggestions to solve my problem, where the air at night in our main bedroom and living room (both upstairs) is hot while the outside air is quite cool. There is generally little breeze at this time of year to bring the cool air inside via an ample number windows, and the wall/ceiling fans just seem to circulate the hot air. The roof is insulated, and while the house is relatively cool during the day I guess the insulation is the problem at night by trapping the hot air inside (indeed, the air in the roof space is much cooler). Can (and do) use the aircon but think there should be a cheaper solution.

Have been thinking about installing exhaust fans in the ceilings and venting the inside air into the roof space, and assume it would be replaced by the cool outside air. Anyone had experience with this approach?

Maybe another possibility is to use fans to pump air directly into the rooms from outside - or perhaps the roof space - but this seems less practical to me given the design of the house and the fans.

Suggestions that have worked especially welcomed!

[oldgit]

I don't think it would be a good idea to extract warm air from the room into the ceiling space,two reasons being:

1) When the extract fan is idle during the day,you could get dust from the roofspace into the room from the fan aperture.

2)When the fan isn't running,you could get warm air from the roofspace into the room through the fan aperture.

I suggest you install a Vent Axia or Xpelair wall or window mounted fan unit(s).The Vent Axia TX series will allow you to pull in fresh air from outside or extract air as it is reversible unit.

[Naam]

"Oldgit" is right when he cautions about drawing back heat and dust. there are (rather expensive) ceiling exhaust fans in the market with a low capacity. i installed them in all the bathrooms, my study and my tv-room because i'm a smoker. ideal is a whole-house fan if you have space to install. i got one which ventilates my house in a few minutes and i do this every morning before the sun is up. it saves a bundle on electricity cost especially in the cool season when outside temperatures are lower than those in the airconditioned house.

[dinga]

Thanks OlGit and Naam - the TX sounds like the solution. Will let you know how it goes.

[bkkbill]

Naam is the photo of a whole house fan? If so what is its size and is that wood above the blades.

Most of the smaller exhaust fans I have seen have a damper located on the exhaust side to prevent dust falling through if mounted horizontally and that should help with the warm air. Thinking about it warm air rises so even with the fan off heat should still escape.

[MESmith]

The ceiling extractor fans I use have a hinged flap that closes off the exhaust when switched off.  The exhaust is at a right angle to the fan, ie horizontal outflow of air drawn vertically through the ceiling.  Closing of the exhaust should prevent dust or warm air entering the living space from the roof space.    

[oldgit]

The ceiling extractor fans I use have a hinged flap that closes off the exhaust when switched off. The exhaust is at a right angle to the fan, ie horizontal outflow of air drawn vertically through the ceiling. Closing of the exhaust should prevent dust or warm air entering the living space from the roof space.

You're talking about a non return damper which works on gravity when the fan is switched off and would certainly seal off the ingress of any dust and dirt from the roofspace.However,you still need to replace the air you are extracting from the room.The Vent Axia TX series incorporates a motorised non return damper which automatically closes when the fan is switched off and provides you with fresh air without opening the windows.

[Naam]

Naam is the photo of a whole house fan? If so what is its size and is that wood above the blades.

Most of the smaller exhaust fans I have seen have a damper located on the exhaust side to prevent dust falling through if mounted horizontally and that should help with the warm air. Thinking about it warm air rises so even with the fan off heat should still escape.

it's a bit difficult to explain. the diameter of the fan is 1 meter, belt driven by a 750 watt motor. the fan is mounted at an angle of ~30º in a small room where all my circuit breakers and some other electrical equipment is installed. the angle was mandatory that the fan can blow through an outside wall instead into the attic. it was not possible to mount it vertically because below is a door leading to the outside. the wood you see are louvers but on the picture one can't see the openings. there is no airflow when the fan is off because then the door to the little room is shut. the idea of the whole-house fan i got when living in Florida where virtually every house built after 1980 had one installed. but these fans were usually blowing into the attic which always had big enough vents to let the air escape. the fans in Florida had dampers, their size were much bigger (diameters of 5 and 6') and driven by 1 and 1½ HP motors. all what i can say is "extremely efficient" but the size not necessarily what the OP needs to solve his problem because of the very loud noise.

[kjhbigv]

Thanks OlGit and Naam - the TX sounds like the solution. Will let you know how it goes.

I have exactly the same issue....don't forget to post how it goes and photo's would be good! Good luck!

[jfchandler]

Oldgit, I'm thinking of doing the same thing for my home...

Can I ask, about what is the purchase price of those kinds of fans, where can they be purchased, and how would the installation be handled, in terms of cost and who doing it.

Thanks much...

I suggest you install a Vent Axia or Xpelair wall or window mounted fan unit(s).The Vent Axia TX series will allow you to pull in fresh air from outside or extract air as it is reversible unit.

[oldgit]

Oldgit, I'm thinking of doing the same thing for my home...

Can I ask, about what is the purchase price of those kinds of fans, where can they be purchased, and how would the installation be handled, in terms of cost and who doing it.

Thanks much...

I suggest you install a Vent Axia or Xpelair wall or window mounted fan unit(s).The Vent Axia TX series will allow you to pull in fresh air from outside or extract air as it is reversible unit.

There is a Vent Axia distributor in Bangkok called IMS International Ltd.Address:Ratchada Orchid Tower.Contact Name:Stephen Teo. Tel.No.026932966 and Fax No.026932965.I suggest you contact them and they will be able to tell you where your nearest shop is that stocks the fans.

As far as installation goes,a TX6WW is a window mounted 6" dia. fan which would require 184mm dia. hole in the glass.You need a glasscutter for that job.The range then steps up to TX7WW,TX9WW and TX12WW.The controller for these fans is a multi speed surface or recessed unit with intake/extract facility.You will need to tell your stockist that you are installing the fan for 'free cooling at night' so you want plenty of air coming into your bedroom.Let me know the size of your room and I'll give you an idea on the fan you want.You need a competent electrician to do the wiring between fuseboard,contoller and fan.He should also be able to install the fan in the glass for you as it is a fairly easy job.I don't know the cost of the fans in Thailand I'm afraid,mate, but in England they were about 100 pound for the TX6WW.The controller was about 35 quid.Best of luck,jf.

[jfchandler]

Thanks very much, OG... Much appreciated...

Just wanted to clarify on two things...

1. When you talk about the unit having a 6 in. diameter, I'm assuming you mean 6 inches being the dimension of the fan blades top-to-bottom and side-to-side...

2. Then re the 7 and 9 and 12WW units you mentioned, I'm assuming, those are 7, 9 and 12 in diameters, likewise...

I've got two ceiling-level windows at opposite ends of my livingroom-joined-with-kitchen -- similar sizes...33 and 31 inches across by 18 inches top to bottom -- that I'm looking at trying to do something with, in one or the other. Both windows are surrounded by thick wood beams on all four sides. Both window panels are above entry doors to outside patios. So I'm assuming either of those window spaces would accommodate any of the fan sizes you mentioned.

Fortunately and unfortunately for me, the combined room area is big with glass windows and curtains on three outward facing exterior walls. And the whole area at present has only one large, floor-standing aircon unit, unfortunately, an older power gulping kind.

The living room area is 23 feet long by 13 feet wide, and then the adjoining kitchen (with connecting open counter and walkway) is another 12 feet by 10 feet. So spacewise in terms of air circulation, it functions pretty much as one big open room, with some of the appliances in the kitchen throwing off a bit extra heat.

Since I'm renting, I can't really see paying to install a newer and more power efficient air con unit. But I could see talking to my house's owner about perhaps splitting the cost of a good window fan unit...

Thoughts????

[oldgit]

Thanks very much, OG... Much appreciated...

Just wanted to clarify on two things...

1. When you talk about the unit having a 6 in. diameter, I'm assuming you mean 6 inches being the dimension of the fan blades top-to-bottom and side-to-side...

2. Then re the 7 and 9 and 12WW units you mentioned, I'm assuming, those are 7, 9 and 12 in diameters, likewise...

I've got two ceiling-level windows at opposite ends of my livingroom-joined-with-kitchen -- similar sizes...33 and 31 inches across by 18 inches top to bottom -- that I'm looking at trying to do something with, in one or the other. Both windows are surrounded by thick wood beams on all four sides. Both window panels are above entry doors to outside patios. So I'm assuming either of those window spaces would accommodate any of the fan sizes you mentioned.

Fortunately and unfortunately for me, the combined room area is big with glass windows and curtains on three outward facing exterior walls. And the whole area at present has only one large, floor-standing aircon unit, unfortunately, an older power gulping kind.

The living room area is 23 feet long by 13 feet wide, and then the adjoining kitchen (with connecting open counter and walkway) is another 12 feet by 10 feet. So spacewise in terms of air circulation, it functions pretty much as one big open room, with some of the appliances in the kitchen throwing off a bit extra heat.

Since I'm renting, I can't really see paying to install a newer and more power efficient air con unit. But I could see talking to my house's owner about perhaps splitting the cost of a good window fan unit...

Thoughts????

Your'e right on both points,mate,although the fan housing,when installed in the window,is almost square in appearance(304mm x 302mm for the TX9WW)It's a nice looking unit.

It's important to highlight that your living room and kitchen with the outside windows ARE adequately ventilated but your prime motive in having these fans installed is for free cooling at night which will require substantially more air than normal ventilation requirements.Ofcourse,this all depends on the outside temperature which can be quite high at certain parts of the year and comfortably low in other months.

I suggest you install 2-no.TX9WW window units,one unit to go in each of the ceiling level windows.At medium speed,each fan will supply over 400 cubic feet per minute of air to the area.This will give you 12 air changes per hour.The hole in each window would be 260 mm diameter.The sound level, for each unit at medium speed, is 52 dBA which is pretty quiet and should be comfortable for anybody that is sleeping.

[jfchandler]

Thanks again... OG... Time to go shopping....

[dinga]

Oldgit, I'm thinking of doing the same thing for my home...

Can I ask, about what is the purchase price of those kinds of fans, where can they be purchased, and how would the installation be handled, in terms of cost and who doing it.

Thanks much...

I suggest you install a Vent Axia or Xpelair wall or window mounted fan unit(s).The Vent Axia TX series will allow you to pull in fresh air from outside or extract air as it is reversible unit.

Just an update - appears the Vent Axia fans are not stocked in Thailand. Have received 2 quotes for the TX7WW model:

* Singapore Distributor: S$677 ea (Baht ~15,850) + S$85 for controller (Baht 1,990) - delivered Bangkok

* China Distributor: GBP 90 ea (Baht 4,293) Ex-Works UK

Are there any other similar reverse airflow fans that are recommended and are available in Thailand? Guess the alternative for me is to wait until we pass through London in October, and pick up the Vent Axia fans then.

[wpcoe]

ideal is a whole-house fan if you have space to install. i got one which ventilates my house in a few minutes and i do this every morning before the sun is up. it saves a bundle on electricity cost especially in the cool season when outside temperatures are lower than those in the airconditioned house.

Naam, how noisy is your whole-house fan? The house I bought for my parents in California has one mounted in the ceiling in the central hallway. It's quite effective at drawing outside air in through open windows/doors, but the vibration and noise prevents it being used more than a couple minutes. I've no experience with a whole-house fan before, so have nothing to compare it to, but have long wondered if it were a defective fan or bad installation. One time I was there, I had my mother cut strips of thick felt and lifted the fan and slid the felt under the fan as a gasket, but that helped only slightly. I've wondered if it would be worth buying a new one, or if in general, those fans are expected to be pretty noisy.

[seanocasey]

iv got same problem in wife's parents house bed room is 14 ft by 22 ft with false ceiling and 1200btu air con leading onto long room whole of house 68 ft by 32ft house has three beds and kitchen, bathroom , main bedroom has two windows single glaze teak room gets very warm no matter how high air con is set also has ceiling fan no use have checked temperature with fan and at night it is still 33-38 c .

worried most about main bed as kid is taken care of by mother in this room what can I do. worried

[oldgit]

Oldgit, I'm thinking of doing the same thing for my home...

Can I ask, about what is the purchase price of those kinds of fans, where can they be purchased, and how would the installation be handled, in terms of cost and who doing it.

Thanks much...

I suggest you install a Vent Axia or Xpelair wall or window mounted fan unit(s).The Vent Axia TX series will allow you to pull in fresh air from outside or extract air as it is reversible unit.

Just an update - appears the Vent Axia fans are not stocked in Thailand. Have received 2 quotes for the TX7WW model:

* Singapore Distributor: S$677 ea (Baht ~15,850) + S$85 for controller (Baht 1,990) - delivered Bangkok

* China Distributor: GBP 90 ea (Baht 4,293) Ex-Works UK

Are there any other similar reverse airflow fans that are recommended and are available in Thailand? Guess the alternative for me is to wait until we pass through London in October, and pick up the Vent Axia fans then.

I's a bit disappointing that Vent Axia don't stock in Thailand when their website states that they have a distributor in Bangkok.The Singapore distributor is a bit pricey but the Chinese supplier prices sound pretty cheap.I would go with them,dinga.

[oldgit]

iv got same problem in wife's parents house bed room is 14 ft by 22 ft with false ceiling and 1200btu air con leading onto long room whole of house 68 ft by 32ft house has three beds and kitchen, bathroom , main bedroom has two windows single glaze teak room gets very warm no matter how high air con is set also has ceiling fan no use have checked temperature with fan and at night it is still 33-38 c .

worried most about main bed as kid is taken care of by mother in this room what can I do. worried

Without the fact that your wife's parents bedroom is 'leading in to a longer room' thereby increasing the area that the split system has to operate,I think it's undersized by at least 3,500 BTU/hr.When sizing a system you need to take into account the internal temperature you want and what the temperature drop would be compared to the outside temperature which would then dictate the total heat gains through the walls,windows,doors,ceiling,floor,people,lighting,machinery i.e TV in the room and infiltration through the cracks in the windows and doors.

Is there any way you can seal off the longer room from the bedroom as this is only exasperating the problem?Also,what does the ceiling fan do?If it's only extracting air from the bedroom then it is creating a negative pressure in the bedroom causing stuffiness?

[seanocasey]

iv got same problem in wife's parents house bed room is 14 ft by 22 ft with false ceiling and 1200btu air con leading onto long room whole of house 68 ft by 32ft house has three beds and kitchen, bathroom , main bedroom has two windows single glaze teak room gets very warm no matter how high air con is set also has ceiling fan no use have checked temperature with fan and at night it is still 33-38 c .

worried most about main bed as kid is taken care of by mother in this room what can I do. worried

Without the fact that your wife's parents bedroom is 'leading in to a longer room' thereby increasing the area that the split system has to operate,I think it's undersized by at least 3,500 BTU/hr.When sizing a system you need to take into account the internal temperature you want and what the temperature drop would be compared to the outside temperature which would then dictate the total heat gains through the walls,windows,doors,ceiling,floor,people,lighting,machinery i.e TV in the room and infiltration through the cracks in the windows and doors.

Is there any way you can seal off the longer room from the bedroom as this is only exasperating the problem?Also,what does the ceiling fan do?If it's only extracting air from the bedroom then it is creating a negative pressure in the bedroom causing stuffiness?

my fault the bedrooms are accessed along the length of long room and there is a door access to bedroom 14ft by 22ft.

[oldgit]

iv got same problem in wife's parents house bed room is 14 ft by 22 ft with false ceiling and 1200btu air con leading onto long room whole of house 68 ft by 32ft house has three beds and kitchen, bathroom , main bedroom has two windows single glaze teak room gets very warm no matter how high air con is set also has ceiling fan no use have checked temperature with fan and at night it is still 33-38 c .

worried most about main bed as kid is taken care of by mother in this room what can I do. worried

Without the fact that your wife's parents bedroom is 'leading in to a longer room' thereby increasing the area that the split system has to operate,I think it's undersized by at least 3,500 BTU/hr.When sizing a system you need to take into account the internal temperature you want and what the temperature drop would be compared to the outside temperature which would then dictate the total heat gains through the walls,windows,doors,ceiling,floor,people,lighting,machinery i.e TV in the room and infiltration through the cracks in the windows and doors.

Is there any way you can seal off the longer room from the bedroom as this is only exasperating the problem?Also,what does the ceiling fan do?If it's only extracting air from the bedroom then it is creating a negative pressure in the bedroom causing stuffiness?

my fault the bedrooms are accessed along the length of long room and there is a door access to bedroom 14ft by 22ft.

Fair enough.Then the next thing to do is get your system checked out as ,even with an inadequate cooling load,it should at least drop the temperature 7-8 degrees C from the outside temperature.It might have a gas leak or the filters are clogged.

[seanocasey]

filters all clogged up cleaned them myself, as it is not my home I was reluctant at first to intrude but on opening up filter screen it was obvious.

how often before gas is changed air installed in 2007 middle of year, not used much as mother in law hates the bill even though i still add 1500 extra every month, we wont go into that.

should I insulate the attic space above the false ceiling.

[Naam]

ideal is a whole-house fan if you have space to install. i got one which ventilates my house in a few minutes and i do this every morning before the sun is up. it saves a bundle on electricity cost especially in the cool season when outside temperatures are lower than those in the airconditioned house.

Naam, how noisy is your whole-house fan? The house I bought for my parents in California has one mounted in the ceiling in the central hallway. It's quite effective at drawing outside air in through open windows/doors, but the vibration and noise prevents it being used more than a couple minutes. I've no experience with a whole-house fan before, so have nothing to compare it to, but have long wondered if it were a defective fan or bad installation. One time I was there, I had my mother cut strips of thick felt and lifted the fan and slid the felt under the fan as a gasket, but that helped only slightly. I've wondered if it would be worth buying a new one, or if in general, those fans are expected to be pretty noisy.

VERY noisy indeed.

[cloudhopper]

This is the unit I'm going to use

http://www.hybridvent.com.au/

[oldgit]

filters all clogged up cleaned them myself, as it is not my home I was reluctant at first to intrude but on opening up filter screen it was obvious.

how often before gas is changed air installed in 2007 middle of year, not used much as mother in law hates the bill even though i still add 1500 extra every month, we wont go into that.

should I insulate the attic space above the false ceiling.

If the system needs gassing up,you will notice an ice build up on the refrigeration suction line at the point of entry to the outdoor unit.It always helps to insulate the loft as it cuts down the heat transfer to the rooms below.

[Naam]

This is the unit I'm going to use

http://www.hybridvent.com.au/

besides my whole-house fan i am using a nearly (technically) identical design (3-phase, 750 Watts for attic and swimming pool area ventilation with a (rather expensive) frequency converter to control the RPMs according to demand. the RPMs were supposed to be adjusted automatically by a heat sensor located in the attic but inspite of all my efforts i never managed to get it running that way, that means i adjust the airflow manually.

[CDNinKS]

Sorry gentlemen if this is a bit off topic, but I'm having a small house built and there is absolutely no attic ventilation. The builder has not put any sofit vents or roof vents to allow any air circulation in the attic. I built 2 house in Canada and proper attic ventilation was critical.

Why is this not done here? The temps in the attic must be astronomical

Edited May 31, 2010 by CDNinKS

[jfchandler]

It's to KILL the rats, of course.

And then, once they're dead, you don't want them sitting around getting rank. So it needs to be hot enough up there to basically turn them into dust...

No vents in the attic ought to handle that just fine...

[oldgit]

This is the unit I'm going to use

http://www.hybridvent.com.au/

besides my whole-house fan i am using a nearly (technically) identical design (3-phase, 750 Watts for attic and swimming pool area ventilation with a (rather expensive) frequency converter to control the RPMs according to demand. the RPMs were supposed to be adjusted automatically by a heat sensor located in the attic but inspite of all my efforts i never managed to get it running that way, that means i adjust the airflow manually.

That fan is an eco friendly roof extract unit which draws the warm air from the area below it and relies on a negative pressure to replace that air with fresh air from outside.Ideal for an open plan area like a roof loft and swimming pool but not for providing ventilation to individual rooms in a house with a false ceiling.Quite impressive air volume figures but what would happen if you added a plenum chamber and ductwork to the fan?Those air volumes would come tumbling down due to the resistance.I'm making this point here in case people think that this fan would 'cool their rooms at night'

[oldgit]

Sorry gentlemen if this is a bit off topic, but I'm having a small house built and there is absolutely no attic ventilation. The builder has not put any sofit vents or roof vents to allow any air circulation in the attic. I built 2 house in Canada and proper attic ventilation was critical.

Why is this not done here? The temps in the attic must be astronomical

It is carried out here but it depends on the builder and whether he's included it in the price .A pitched roof extract fan (as shown previously) would suffice with a couple of fresh air inlet louvres,if you have end walls.