Ceiling exhaust fans

[manofthecoldland]

2 minutes ago, GeoffH said:

I agree those work well, I haven't seen them in the Philippines though.

Be careful that the ones you get are well made, we put them on the work shed a bit before I retired and one of them developed a really really annoying squeek as it rotated and we had to get a plumber to fix it.

They work better than their predecessors...... which were basically a rain capped snorkel with a wind vane. But many now use ridge line venting, which is passive and extensive...shortest path from soffit to apex. They are considered the most effective and economical when installed properly.

[jimeve]

7 hours ago, Viking said:

I understand they are often installed in bathrooms to reduce the humidity, but I am also curious to find out if they are effective in reducing the temperature in other rooms? Since hot air rises, it sounds like a good idea with a ceiling exhaust fan to vent it out.

I have small exhaust fans installed in all my bathrooms, just to get rid of the steam and humidity. They work okay but not sure they would make the rooms cooler. better to leave open the windows all the time.

[hk blues]

3 hours ago, jimeve said:

I have small exhaust fans installed in all my bathrooms, just to get rid of the steam and humidity. They work okay but not sure they would make the rooms cooler. better to leave open the windows all the time.

We've been 5 years in our place - we have a shower heater.  We only have a window for ventilation - it's always open and we haven't experienced any issues so far.  

A fan is a good idea if easy to install and ventilate.

[Viking]

19 hours ago, Old55 said:

Our home in US has roof vents and an automatic thermostat controlled attic fan. This reduces the temperature of our house significantly during the short summer months here.

I know of attic fan/roof vent fans that are photocell powered. Those could be a good choice for Philippines.

I have also been looking on attic fans but now I was more thinking of the small fans in the ceiling, that ventilate the hot air from inside the rooms.

Something like this:

https://www.lazada.com.ph/products/omni-ceiling-mounted-exhaust-fan-12-inches-inch-xfc-300-12-xfc300-12-xfc-300-12-genuine-and-original-i290138168-s469906202.html?spm=a2o4l.searchlist.list.28.3

I guess a solarpowered fan would be ideal for this since it is during daytime you need it the most.

[Viking]

14 hours ago, Joey G said:

They work great... if you get one big enough (like 3000-4500 cfm), it can change the temp inside in a few minutes. Works best if you can close windows and doors and suck all the air out through one window or door.  But again it needs to be big... the small ones do little.

Is it really necessary with big fan?

My plan was to use a small fan, since the hottest air will be at the top of the room and its the hottest air we want to ventilate.  The idea with a small fan is that it can be turned on during a big part of the day since they dont use much electricity. They will obviosly not lower the temp as fast as a big one but since they are on, most of they day, I guess the heat will not build up very much. 

[Viking]

12 hours ago, BrettGC said:

We're in the process of sourcing "whirlybird" or similar roof vents for our place.  Very common in Australia, not so much in PI particularly during lockdown.  They're not powered but rather the rising hot air in the roof cavity causes them to spin drawing the hot air out.  They're most effective if there's vents in the ceiling and under the eaves.  

I installed some in my place on the Gold Coast in Australia, the difference in the ambient temperature was immediate during the summer.  

 

I been looking on these too but I was not sure if they were effective without wind? Sad to say, our place don´t have much wind so I have been hesitating to install whirlybirds. Do you have good experience from them even when there is no or only very little wind?

You can now by whirlybirds which is connected to a solarpanel and that will probably increase their effectivness when there is no wind. 

I think this solution is best for the attics and I was more thinking of ceiling fans. However, if the attic is cooler the room under it will also be cooler 

[graham59]

They're widely used on poultry and pig units, and industrial buildings...those 'whirlybird' vents.  

I have (on most of our rooms) the traditional gap between top of wall and roof, but my 'gap' is also protected by wire mesh, to keep out any vermin larger than a cockroach.   

All windows are kept open, with just the mosquito screens in place. This ensures that our non-aircon home is comfortably cool at all times. 

[Tukaram (Tim)]

The only roof ventilators I have seen here are huge, like for barns.  I asked about small ones for the house and everyone looked at me like a was crazy. As an old HVAC man I know that the roof ventilators make a huge difference.

We have a fart fan in the CR, but as you can tell by the name it is not for removing humidity ha ha 

[Joey G]

3 hours ago, Viking said:

Is it really necessary with big fan?

My plan was to use a small fan, since the hottest air will be at the top of the room and its the hottest air we want to ventilate.  The idea with a small fan is that it can be turned on during a big part of the day since they dont use much electricity. They will obviosly not lower the temp as fast as a big one but since they are on, most of they day, I guess the heat will not build up very much. 

My experience... a large exhaust fan (they are called whole house fans) is necessary to move large volumes of air... the idea is that when the temp outside drops 5+ degrees you can take that all that cooler air in quickly. A small fan won't get you that temp change, and won't keep up enough with the heat of day. Electricity wise you would only run the large exhaust fan for a few hours each evening.  And there's an extra benefit... they are also great for clearing the air after frying... especially dried fish LOLOLOL

The vent fans are best used for keeping hot attics cooler so the lower part of the house doesn't get hot.  If you used a vent fan during the day for the living area, you will likely being drawing air in from the outside that  is hotter than the inside is. If you have a high ceiling though (12'+)  the vent fan might be worth doing during the day.

[sonjack2847]

22 hours ago, BrettGC said:

We're in the process of sourcing "whirlybird" or similar roof vents for our place.  Very common in Australia, not so much in PI particularly during lockdown.  They're not powered but rather the rising hot air in the roof cavity causes them to spin drawing the hot air out.  They're most effective if there's vents in the ceiling and under the eaves.  

I installed some in my place on the Gold Coast in Australia, the difference in the ambient temperature was immediate during the summer.  

 

Citi hardware sells them so not hard to find here. I have them at my place.