How beneficial is an attic fan?


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Old 07-10-11, 07:48 AM
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How beneficial is an attic fan?

We're having an issue on really hot days (upper-80's +) with the AC keeping the living room cool. It keeps the rest of the house cool, but it always feels warmer in the living room/kitchen area. The thermostat is set to 80, but the temp reads 84.

The AC/heating unit is 10 years old. We had an AC person out last week to give us an estimate on a new unit and he felt that while the AC unit is near end-of-life, our main problem was the high ceilings (they're 12' in the living room/kitchen area. He mentioned that putting a ceiling fan in may help in that regard.

So, the question is, would a ceiling fan help with our problem in the LR/kitchen area? Is it worth the $600-$800 price tag?

Thanks,

Andy
 
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Old 07-10-11, 08:15 AM
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First...lets clarify....your title says attic fan...but you mention ceiling fan in the body of the post. They are very different.
 
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Old 07-10-11, 09:06 AM
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I think GG is correct, you are talking about a ceiling fan, not an attic fan. But in any case, the issue is probably that high ceiling and the limited ability to insulate it from the heat above. If your room is 84°, then the temp up high in that room will be much higher. My guess would be circulating that heat down to the people level and your 84° air up to that ceiling will both make the room feel hotter and increase the heat gain from above. Wrong solution.

If they were suggesting an attic fan, that would be thinking in a better direction, reduce the heat above. That's worth considering, but the first step is to check your high and low venting to be sure it is properly sized and working.

Clarify and let us know where you are going.

bud
 
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Old 07-10-11, 11:30 AM
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You probably have a problem with the design of your duct system. You could be under supplied to the living room, or have to much leakage in the ducts that go there. Is the living room more exposed to direct sunlight than other parts of the home? Is there a lot of glass in the living room?
 
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Old 07-10-11, 05:24 PM
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Sorry for the confusion. I do mean ATTIC fan (we do have a ceiling fan and it helps, but it's still warm. For example, right now it's 86 outisde, 85 in the house, and the digital thermostat is set to 80). The living room has two vents, and the kitchen has one vent. We do have quite a few windows, but we keep the shutters closed to keep down the sunlight.

I'm not sure what you mean by "high and low venting". The only vents we have are in the floor, and there is a return register in the living room/kitchen (if a picture of the room would help, let me know and I'll get one posted).

Also, in the crawl space, we have the large "tubes" for the duct work (not the metal/galvanized box type I'm used to seeing).

Thanks,

Andy
 
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Old 07-10-11, 07:06 PM
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The reference to high and low venting was wanting to know how the hot air is currently getting out of your attic. High vents are usually a ridge vent or gable vents. Low venting could be under the eaves called soffit vents.

Another simple check is the temperature of the air coming out of those vents in that room. How much colder is the cool air verses the room temperature?

Trying to narrow it down to the ac unit, the delivery system, or heat gain in the house/room.

Bud
 
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Old 07-11-11, 07:39 PM
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Bud,

We have high vents (going by your description). I bought a cheap digital thermometer
today. I don't think it's accurate (since it was registering a temp of 87.7 out of the vent, but the air felt cool). But, I can say there was only a .5 degree difference between the air coming out of the vent and the ambient room temp (I set it in place in the middle of the room on a side table for 30 minutes, and put the sensor on the register for 30 minutes as well).

We had a yearly check-up of the unit a few months ago. When they do an inspection, do they also check the freon levels?

Thanks,

Andy
 
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Old 07-11-11, 08:29 PM
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The vents I'm asking about are on the roof and you need top of the roof to let hot air out and under the eaves to allow cooler air into the attic.

If you are getting those temperatures, then all you have is moving air. Do the same test in all other rooms to be sure they are working.

Bud
 
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Old 07-17-11, 05:50 AM
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Here's a few things I can suggest. I am not an expert, but I just went through this recently:
1. I would adjust the returns by reducing the flow in colder rooms and opening wide the warmer ones.
2. Make sure the supply ducts are clear in the warmer area. Perhaps vacuuming the whole house ducts could help if you have pets.
3. Seal all the ducts with mastic. Tape larger openings.
4. Completely insulating the attic. (I've read a few articles stating that insulating the attic is more beneficial than the attic fan, so I removed mine and had it insulated. Attic fan costs $40-50 and a couple of hours to install, however, it also draws power and works pretty much around the clock, so that's also a thing to consider when installing one.)

I am shocked that your 10 year old system is at the end of it's life. It should last another 10 with no problem if maintained properly.
 
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Old 07-17-11, 04:07 PM
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Most people will tell you that your atti should be the same temperature as it is outside. In the summer, I'm guessing your attic is well over 100 degrees when it's in the 80s or 90s outside. This basically puts a huge cushion of really hot air right above your ceiling. This makes the upper area of your rooms hot while the lower area is cooler.

Yes, if you have enough insulation you won't notice it as much, but you'd notice it less if the attic was much cooler.

Yes, attic fans use electricity but most have thermostats so you can set them to only run when it's over XX degrees or something like that. They work by blowing the hot air out and letting the outside air come in to reduce the temperature in the attic. THey also have solar power ones that just run all the time. However I've never seen them for $600-$800. More like $100 - $200 for regular ones and $200 - $300 for the solar models.

Here's one a solar one:
Solar Powered Roof Fan - WW at Menards

and here's the whole lots:
Search Results for "roof fan" at Menards

Good luck.
 
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Old 07-17-11, 04:34 PM
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Well OK, now that brings up another kind.

Other fans are called Whole House Fans. Those fans go in the ceiling of a room and blow into the attic. The point of those is to draw in into the house from outside, through the fan, up into the attic, and then out the attic vents.

Those fans I have heard specifically NOT recommend by lots of people including general contractors. We had one in our house and took it out since we never used it anyway. I would recommend an actual Attic Fan / Roof Fan but not a whole house fan. I guess it depend son what terminology everyone uses.
 
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Old 07-25-11, 02:17 PM
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Well, we put up some window film that is supposed to block 70% of the heat coming in. This was put on the four large windows in the living room. When that didn't help, we decided to call the AC people. Good thing we did.

It turns out we were low on freon. When he pulled the over on the unit, all the lines coming out of the compressor were iced up. After taking a hose and thawing the pipes, he charged the system and we're much better now. We did a day or two after he did that that it wouldn't go below 82 (the outside temp was 100), but since then, it has kept it where we want it (at 80, which is comfortable for us).

Thanks for all who replied. We still might look into putting more insulation in the attic.

Andy
 
 

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