I came across this product that will extract the hot air from your home: https://quietcoolsystems.com/whole-house-fan/stealth-pro-x-whole-house-fan/

 

I thought it would be possible to rig up your own version using ducting (http://www.ductexcel.co.th/en/flexible-duct/)  and fan (https://www.artith.com/detail/Mi0zNg==/Type-AV-Exxx) 

 

In our house the ground floor is cooled by two AC units but the upstairs is very difficult to cool in the day time. We have insulation in the roof space.

 

My question is would this just suck out the cooled air from downstairs straight out the roof?

Do you have ventilation and/ or fans in the roofspace  already ?

No. Maybe a gable fan would be a better idea?

https://quietcoolsystems.com/attic-fan/smart-gable-attic-fans/

 

Is the "attic" vented? Do this first. After that I would install a rooftop ventilator (or a few).

 

I believe the "whole house" fans are generally used when the ambient temperature is nice.

In addition to roof void space venting, as mentioned,  along with insulation, whole house fan has its place as an optional feature to remove accrued heat from fixtures and furniture within the living space.  Always remember long-time TVF member, Naam, swore by it for early morning use, before kicking on the a/c units. 

 

Never pursued it myself, rather, installed a less expensive 18" window exhaust fan in the back bathroom.  Produces a reasonably good suction for our modest 3bed/2bath single story house, and also helps remove transient odors from the house - cooking, etc. 

Whole house fans work great in Denver, CO where the temps drop into the cold zone at night.  In Thailand night temps are almost the same as day temps and not what you want to sleep in if not located on a mountain.   The key to use is open windows on ground floor/closed on second to pull air through house and out through attic

48 minutes ago, pj123 said:

No. Maybe a gable fan would be a better idea?

https://quietcoolsystems.com/attic-fan/smart-gable-attic-fans/

Yes, that would help.  Fan or even just passive venting on both vertical ends to reduce some of the heat build up.  If you don't have already, consider slotted eave boards. 

 

The insulation you have is less effective if the attic void space isn't vented.

Yes that all makes good sense. I will look at installing a gable fan. It will require cutting a hole in the gable brick wall.

1 minute ago, pj123 said:

Yes that all makes good sense. I will look at installing a gable fan. It will require cutting a hole in the gable brick wall.

What kind of roof do you have?

 

Are your eaves vented?

5 minutes ago, Yellowtail said:

What kind of roof do you have?

 

Are your eaves vented?

No. I have seen the slotted boards that people fit under their eaves. Like this: https://www.homepro.co.th/p/1075024

I have cooled many houses by simply installing the standard flat bathroom quiet fans in place of the attic access doors, sucking hot air from the highest part of the inside of the house and blowing it directly into the attic space.  I install the largest exhaust fan i can fit onto a new plywood door, costing under 1000 baht all in. With all the windows closed, cool air is drawn up from the lower levels.

 

You mentioned you have insulation already, but it is also very important to keep the attic cool by making sure you have lots of attic venting. The air has to be allowed to get into the attic freely from somewhere, most often through the soffit venting, or even by gable end vents. You must also allow the hot attic air to escape, either by the gaps in the very loose roof tiles, or turbine vents near the highest part of the roof.  You can use a handheld infrared thermometer on a hot day inside the house to find out where your heat is coming from. The roof tiles heat up tremendously during a sunny day, and radiate heat downward into the attic until they slowly cool after the sun goes down. Darker tiles are worse. For side wall heat issues, you might try shielding it from the sun by using vegetation like trees, or a hanging roller sunshade. Using fans at night drawing air through the house helps cool the entire mass down for a portion of the next day.

 

In my last large 2 story house, it cooled so well at night, as I closed the windows and curtains during the day, I did not even need to use aircon.

6 minutes ago, Gold Star said:

In my last large 2 story house, it cooled so well at night, as I closed the windows and curtains during the day, I did not even need to use aircon.

Perhaps your location helps - most of Thailand will not cool anywhere near as much at night (23c average this week it seems).

Quote

Location:Chiang Rai

 

1 hour ago, Yellowtail said:

After that I would install a rooftop ventilator (or a few)

I spent Bht 26000 on two whirly birds. No difference whatsoever, even with my vented eaves and soffits, and a ceiling extractor fan. 

Some folks like their whirly birds, some don't. 

 

I went with a passive vent contraption from SCG, 4,900 Baht, mounted on the same kind of tile we have - pull 1 tile out, slot this thing in its place.   Only had one available, ordered up from BKK, said the un-powered model went out of production, but they could make more on demand.  Chucked the single unit up there to test through a rain season first.  So far so good, likely order 3 more before next summer.

 

 

 

2 hours ago, KannikaP said:

I spent Bht 26000 on two whirly birds. No difference whatsoever, even with my vented eaves and soffits, and a ceiling extractor fan. 

I bought two at 3,500 each installed and the difference is night and day. 

49 minutes ago, Yellowtail said:

I bought two at 3,500 each installed and the difference is night and day. 

He appears to already have had extractor fan if I am reading his post right - and ventilation of attic - so probably not much more they could do.  They indeed can make a big difference in ceiling heat transfer from a closed attic with cement board ceilings.  

1 hour ago, Yellowtail said:

I bought two at 3,500 each installed and the difference is night and day. 

What size are they. Mine are 22 inches. They rotate fairly quickly but no great advantage. 

3 hours ago, 55Jay said:

Some folks like their whirly birds, some don't. 

 

I went with a passive vent contraption from SCG, 4,900 Baht, mounted on the same kind of tile we have - pull 1 tile out, slot this thing in its place.   Only had one available, ordered up from BKK, said the un-powered model went out of production, but they could make more on demand.  Chucked the single unit up there to test through a rain season first.  So far so good, likely order 3 more before next summer.

 

 

 

I looked at these, but came to the conclusion that simply removing a tile would have the same effect, except no rain coming through.

 

55 minutes ago, KannikaP said:

I looked at these, but came to the conclusion that simply removing a tile would have the same effect, except no rain coming through.

 

With a buttoned up Hip style roof, I went with this vent box on a tile adapter to simply let the hot air vent up and out naturally, without any moving parts in the way.  If I had a Gable roof, would of done what the OP plans to do. 

1 hour ago, lopburi3 said:

He appears to already have had extractor fan if I am reading his post right - and ventilation of attic - so probably not much more they could do.  They indeed can make a big difference in ceiling heat transfer from a closed attic with cement board ceilings.  

I understood he had no venting and no fan.

1 hour ago, KannikaP said:

What size are they. Mine are 22 inches. They rotate fairly quickly but no great advantage. 

16"

1 minute ago, Yellowtail said:

16"

Name of supplier/fitter please as I think I need two more.

10 hours ago, Yellowtail said:

I understood he had no venting and no fan.

We were responding to KannikaP.

23 hours ago, lopburi3 said:

Perhaps your location helps - most of Thailand will not cool anywhere near as much at night (23c average this week it seems).

 

Oops, yes agreed if in Chiang Rai. I missed to say that my last house was near Pattaya. 

20 hours ago, KannikaP said:

Name of supplier/fitter please as I think I need two more.

I do not know the name, but I will talk a photo the next time I go by.

 

Do you know where the Lat Krabang Airport Link station is? 

11 minutes ago, Yellowtail said:

I do not know the name, but I will talk a photo the next time I go by.

 

Do you know where the Lat Krabang Airport Link station is? 

No, I am in Phitsanulok. Mine were Bht 5000 EACH plus Bht 1000 transport, then a further

Bht 11,000 for two men to come from Bangkok and fit them. I know I was probably ripped off. 

7 minutes ago, KannikaP said:

No, I am in Phitsanulok. Mine were Bht 5000 EACH plus Bht 1000 transport, then a further

Bht 11,000 for two men to come from Bangkok and fit them. I know I was probably ripped off. 

Two guys three days, meals and lodging.

 

 

6 minutes ago, Yellowtail said:

Two guys three days, meals and lodging.

 

 

No, done in a couple of hours. But of course, 5 hours drive each way plus fuel.

 

Sorry, just looked at the invoice........Bht 5000 for fitting, so the whole lot was Bht 16,000. 

Just now, KannikaP said:

No, done in a couple of hours. But of course, 5 hours drive each way plus fuel.

 

I thought it was further. I assumed a day up, and a day back. 

 

The shop that did mine is about 15 minutes away, they brought them with them and were done in an hour. 

 

They came back with and couple pieces of flashing the next day and stuck those on.