# Whole house fan over garage?



## lbzdually (Jun 30, 2012)

We have a bonus room in our house with seperate AC controls for it by itself.  Even with it set at 76, the temp will not get below mid 80;s during the day.  It is pretty well insulated except for the door, a cheap hollow core that I taped a piece of foam over to insulate.  On the lower level, the AC is barely keeing up also.  We built our house 4 years ago and it is well insulated.  What I want to do it put a whole house fan ran off a switch over the garage as it is connected to rest of the attic.  I would mount it to draw hot air from the attic out through the garage.  That way it would kill two birds with one stone with keeping the attic cooler and getting air movement.  I may even do a thermostat also to allow it to shut off automatically if I forget after dark.  Another advantage of having the fan over the garage is that is will be quiter over there away from the maon part of the house. 

What do you guys think of this?  It would be downfiring.


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## westcobbdog (Jul 1, 2012)

what about ridge vent for your roof or power ventilator for your attic? attic may be too hot, making it tough to cool?


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## Hogwild80 (Jul 1, 2012)

If ya house was built by a contractor and they contracted to put ya ac in they put bare minimum for the size and this heat will make one in top working shape work overtime is ya thermostat in direct sunlight like near a window that could give one a false reading. How many square feet is ya addition and what size is ya unit.


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## Hogwild80 (Jul 1, 2012)

You said seperate ac controls I'm assuming it is a zone system right ran off a single ac system.


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## jimbo4116 (Jul 1, 2012)

lbzdually said:


> We have a bonus room in our house with seperate AC controls for it by itself.  Even with it set at 76, the temp will not get below mid 80;s during the day.  It is pretty well insulated except for the door, a cheap hollow core that I taped a piece of foam over to insulate.  On the lower level, the AC is barely keeing up also.  We built our house 4 years ago and it is well insulated.  What I want to do it put a whole house fan ran off a switch over the garage as it is connected to rest of the attic.  I would mount it to draw hot air from the attic out through the garage.  That way it would kill two birds with one stone with keeping the attic cooler and getting air movement.  I may even do a thermostat also to allow it to shut off automatically if I forget after dark.  Another advantage of having the fan over the garage is that is will be quiter over there away from the maon part of the house.
> 
> What do you guys think of this?  It would be downfiring.



Bad idea.  You will be drawing in out side air and exhausting out your garage. Meaning you will need to keep you garage door open at all times.

Not knowing what type of venting you have for your attic, i.e., eve vents with ridge vent.  Gable end vents or roof vents complicates the issue.

The whole house fan with a down draft would also pull down dust and loose insulation. You will be drawing moisture into your attic (possibly rain) into your attic and garage. Also if you don't have enough venting for the fan from the outside you will draw cooled air from the living space.

Best solution are power ventilation fans matched to the size of your attic and existing ventilation system..  Gable or roof mounted and some additional blown in fiber insulation in the attic spaces.  You may also want to have a few different HVAC contractors look at your system.  You may have problems there.


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## shakey gizzard (Jul 1, 2012)

jimbo4116 said:


> Bad idea.  You will be drawing in out side air and exhausting out your garage. Meaning you will need to keep you garage door open at all times.
> 
> Not knowing what type of venting you have for your attic, i.e., eve vents with ridge vent.  Gable end vents or roof vents complicates the issue.
> 
> ...



This!^^^ Hot air is hot air, no matter how fast you push it!


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## DAWG1419 (Jul 1, 2012)

The way it was explained to me once when temps get over 100 just bet the ac will run all day. My did yesterday when it was 107.3 here


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## Hogwild80 (Jul 1, 2012)

There designed to run at a certain ambient temp when it gets over that it works overtime.


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## Oldstick (Jul 1, 2012)

I've done the whole house fan in the garage thing before.

  But as someone mentioned, it has to be a situation where you have a back door or something to the garage you are willing to leave at least partially open when the fan is running.  Or you will have to leave your big garage door open six inches or so.

If you do, I recomened blowing up into the attic however.  Then you can use it to draw cool air through your house in the spring and fall by closing up the garage and putting a screen door on the house entrance in the garage.

I'm pretty sure they draw more power than the standard attic vent vans, so really those would be better if you are only going to use it for attic ventilation.


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## mattech (Jul 1, 2012)

http://forum.gon.com/showthread.php?t=695118


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## dixiedoug (Jul 1, 2012)

The air in the house is moved by the HVAC system and cooled or heated as it moves.  The attic should be insulated, but the main thing is to move the air.  Most houses have too few returns or are poorly configured when it comes to ducts.  A HVAC guy can look to see what the problem is.  Sometimes it is the filter.  My son is HVAC
guy and this is what he tells me.  The attic fan is not going to help cool the house.  He fixed my bonus room over the garage and now it is the coolest room in my house.


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## lbzdually (Jul 1, 2012)

There are 3 vents upstairs with a seperate return for upstairs.  The air coming out is very cool.  The problem is the air upstairs is stagnant with no fresh air getting drawn in.  I would say it is well over 140 degrees up there by 11 in the am.  Just having a fan that would draw in 100 degree air (or whatever the outside temp is) to displace the 140 degree air would make the AC system work a lot easier.   I turned the AC to 72 today and it is holding, downstairs.  The bonus room is set to 76 right now and it is 90 degrees up there.  I looked at fans and most seem to draw upwards, so it would draw the cooler air out of the garage.  We have two windows in the garage we keep open during the day and we usually leave the garage door open also.  

We have a ridge vent and soffit vents, but there is nothing drawing in outside air.  If I do this, I will get before and after temps up there.  I will have a thermostat that cuts it on at 100 degrees.  I have an extra wire ran to a switch, so I can manually shut the fan off also.  

We spec'd the ac unit with guidance from the AC people, not the contractor.  I think we have a 2 1/2 ton Carrier unit that runs the two zones.


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## lbzdually (Jul 1, 2012)

dixiedoug said:


> The air in the house is moved by the HVAC system and cooled or heated as it moves.  The attic should be insulated, but the main thing is to move the air.  Most houses have too few returns or are poorly configured when it comes to ducts.  A HVAC guy can look to see what the problem is.  Sometimes it is the filter.  My son is HVAC
> guy and this is what he tells me.  The attic fan is not going to help cool the house.  He fixed my bonus room over the garage and now it is the coolest room in my house.



Explain to me how a 140-150 degree attic does not affect the cooling ability of the room right next to it.  The top of the bonus room has 10-12 inches of cellulose insulation and the walls have R-25.   I may not be able to get the attic temp down to ambient temps outside, but even if I can get it down to 110-120, that would be huge over 150.


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## lbzdually (Jul 1, 2012)

This is the one I'm looking at, or something similar. http://www.northerntool.com/shop/tools/product_200354625_200354625


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## shakey gizzard (Jul 1, 2012)

Depending on your roof pitch, What about a couple passive "spinner " vents?     http://www.nrca.net/consumer/attic_ventilation/passive.aspx


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## lbzdually (Jul 1, 2012)

shakey gizzard said:


> Depending on your roof pitch, What about a couple passive "spinner " vents?     http://www.nrca.net/consumer/attic_ventilation/passive.aspx



I had thought about those, but I've also got the idea that when it starts cooling down some, I can shut garage door, shut garage windows, open the door between garage and house, then turn on the fan and let it cool down the house too.


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## shakey gizzard (Jul 1, 2012)

lbzdually said:


> I had thought about those, but I've also got the idea that when it starts cooling down some, I can shut garage door, shut garage windows, open the door between garage and house, then turn on the fan and let it cool down the house too.



That would be counter productive! You'd be blowin hot attic air through the house! the goal is to cool the attic air! When the temps are just right, I put afan in one window(upstirs ) blowing out. The other on the opposite side of the house, blowing in! Beware the outside humidity doing this!


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## 1gr8bldr (Jul 1, 2012)

My bonus room has a harder time keeping up. Blinds helped. Many are on a thermostat with the rest of the house. This will not work. But you said yours had it's own thermo. It is possible that the "box" that diverts from one area to the other has gone bad. Are you getting cool air through your vents? If not, your diverter box has gone bad. That is not the proper word, but basically is just that. If your getting cool air but not enough to bring down the temperature, It could be like mine. The insulation to the roof has just enough space to breath. But heat tranfer is much greater because it is so close as opposed to the roof in a typical attic being so much higher. It is not a good design for summer. My roof has ridge vent but is very inefficient. Heat does escape, but not even as fast as heat builds and transfers. It needs a gable power vent. This I plan to do to my own. Mine involves removing brick that goes to the peak just to be able to install the gable vent. I could cut in a square vent but they don't look good pushed up to the top and in most clipped bonus room situations, the ceiling joist are closer to the  ridge than non clipped. So, an "A" vent is the answer. On both sides. This alone could be enough to let hot air escape more effeciently. But since the power vents come with a thermo on/off, why not use it. Lowes has 2 sizes. One for about $80 which would cover a bonus room or average attic and a larger for $120. You would create a"radiator" effect. Circulating the hot air out, pulling in the cooler air. In the process, you are bringing down the temperature of the "block" or everything in the attic, wood, insulation, drywall. The transfer of heat is much less. So, with the thermo set, it would not run in the winter when you wish for that same effect that hurts you now. Good luck.


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## lbzdually (Jul 1, 2012)

shakey gizzard said:


> That would be counter productive! You'd be blowin hot attic air through the house! the goal is to cool the attic air! When the temps are just right, I put afan in one window(upstirs ) blowing out. The other on the opposite side of the house, blowing in! Beware the outside humidity doing this!



If I open the windows in the house, shut off the garage from the outside, open the door leading to the attached garage and let the fan suck air into the attic, it will pull cool air from outside through the house into the attic.  Notice I also said, when it cools down, like when lows get back into the 50's and low 60's.   I'm bad about not making people understand what I am saying and I'm sorry if I confused you.


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## Hogwild80 (Jul 1, 2012)

How many square feet is ya house not trying to question ya every word just trying to help I do hvac work and have for over fifteen yrs, I would say in this heat it could prob affect your system some,in your attic, also there are two different types of flex if that's what you have the r values are different between the two because of that reason HEAT ya system in ya attic is designed for a broad spectrum of applications


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## shakey gizzard (Jul 1, 2012)

lbzdually said:


> We have a bonus room in our house with seperate AC controls for it by itself.  Even with it set at 76, the temp will not get below mid 80;s during the day.  It is pretty well insulated except for the door, a cheap hollow core that I taped a piece of foam over to insulate.  On the lower level, the AC is barely keeing up also.  We built our house 4 years ago and it is well insulated.  What I want to do it put a whole house fan ran off a switch over the garage as it is connected to rest of the attic.  I would mount it to draw hot air from the attic out through the garage.  That way it would kill two birds with one stone with keeping the attic cooler and getting air movement.  I may even do a thermostat also to allow it to shut off automatically if I forget after dark.  Another advantage of having the fan over the garage is that is will be quiter over there away from the maon part of the house.
> 
> What do you guys think of this?  It would be *downfiring*.



Were gettin closer!


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## lbzdually (Jul 1, 2012)

shakey gizzard said:


> Were gettin closer!



After looking at it, the fans are all updraft.  I thought one of my other posts conceded that.


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## lbzdually (Jul 1, 2012)

Hogwild80 said:


> How many square feet is ya house not trying to question ya every word just trying to help I do hvac work and have for over fifteen yrs, I would say in this heat it could prob affect your system some,in your attic, also there are two different types of flex if that's what you have the r values are different between the two because of that reason HEAT ya system in ya attic is designed for a broad spectrum of applications



Bottom on the house is 2400 sq ft, give or a few ft and the bonus room is about 300 sq ft.   I can't remember the ton rating on the AC unit for sure.


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## lbzdually (Jul 1, 2012)

lbzdually said:


> I looked at fans and most seem to draw upwards, so it would draw the cooler air out of the garage.



  I thought I had said that, just proving I haven't completely lost my mind.


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## Oldstick (Jul 2, 2012)

lbzdually said:


> I thought I had said that, just proving I haven't completely lost my mind.



What you are thinking will definitely work.  Doesn't matter if you pull or push the hot air from the attic.  Just need to make sure you have adequate vent holes in the attic and most folks do with ridge vents and soffet vents.  The total square footage of the vent openings should be at least equal to the square footage of the fan opening or thereabouts.

Some folks seem to think you are proposing to run the fan through through your house during AC weather.


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## shakey gizzard (Jul 2, 2012)

lbzdually said:


> I thought I had said that, just proving I haven't completely lost my mind.



Gotcha! It will work, but I'd think youd get more use outta a thermostatically controled gable vent! Whatever route, like oldstick said, make sure your vents(soffit) arent blocked or you have enough.


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## Hogwild80 (Jul 2, 2012)

Has your airconditioner been serviced any.


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## Hogwild80 (Jul 2, 2012)

If you have a 2 1/2 ton unit running both zones no wonder neither upstairs or down stairs will cool off.It's usually 500 square foot per ton and you said you had a total sq ft approx 2700 my home is 2000 sq ft and I have a four ton, works great two story house.


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## lbzdually (Jul 2, 2012)

shakey gizzard said:


> Gotcha! It will work, but I'd think youd get more use outta a thermostatically controled gable vent! Whatever route, like oldstick said, make sure your vents(soffit) arent blocked or you have enough.



We have 3 gable vents and soffit vents, also, so air flow should not be a problem.


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## lbzdually (Jul 2, 2012)

Hogwild80 said:


> If you have a 2 1/2 ton unit running both zones no wonder neither upstairs or down stairs will cool off.It's usually 500 square foot per ton and you said you had a total sq ft approx 2700 my home is 2000 sq ft and I have a four ton, works great two story house.



I just looked up the model number on the unit and it is a 3.5 ton unit.


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## Hogwild80 (Jul 2, 2012)

Hey man here's a website kinda showing ya what I was talking about the size unit right for your home,   www.acdirect.com/systemsize.pup


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## Hogwild80 (Jul 2, 2012)

The last is supposed to he php


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## Jeff C. (Jul 2, 2012)

Not enough ventilation and sounds like the system is too small. I have a 4 ton unit on a 2400-2500 sq ft home including the bonus room over garage. I run 2 thermostatically controlled power ventilators on roof, 9 turtle back vents, and the vinyl soffit is vented every foot. I'm using one system and one thermostat downstairs and there is only a 4-5 deg difference. Yesterday I was maintaining 73 downstairs and about 78 upstairs in the bonus room.


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## Hogwild80 (Jul 2, 2012)

4 ton on a 2500 sq ft is still too small you prob just getting by with all your ventilation in your attic but can't blame anyone not wanting to hear their unit was improperly sized for the home.


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## Jeff C. (Jul 2, 2012)

Hogwild80 said:


> 4 ton on a 2500 sq ft is still too small you prob just getting by with all your ventilation in your attic but can't blame anyone not wanting to hear their unit was improperly sized for the home.



Not according to my HVAC man....it was 3.5 ton and was upgraded to a 4 ton unit. I've got the 14 seer eqpt., I believe. House is very well insulated, expensive windows and doors, properly ventilated, and proper run times. Electric bill reflects the efficiency that I'm getting, a heat loss was done at the time it was built and one of the best HVAC guys I've ever known installed it.

If it was too small it wouldn't be keeping my bonus room within 4-5 deg of my downstairs with no zone for the upstairs. I could have turned down below 73 yesterday.
I'm far from getting by....


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## Hogwild80 (Jul 2, 2012)

Yeah, its normally 500 sq ft per ton. I do HVAC work myself and have for the past fifteen + years but ok.Normally if your system is sized right it wouldn't stay 78 in a space when your thermostat was set on 73


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## Jeff C. (Jul 2, 2012)

Hogwild80 said:


> Yeah, its normally 500 sq ft per ton. I do HVAC work myself and have for the past fifteen + years but ok.Normally if your system is sized right it wouldn't stay 78 in a space when your thermostat was set on 73



Normally, when you have a bonus room over a garage you zone your system or have a separate system. Mine is doing it on one unit with one thermostat, downstairs. 

My Hvac guy has 30 some odd yrs experience, very well schooled in all aspects of HVAC, Refrigeration, and Commercial HVAC.

For the zone we live in a 4 ton unit is energy efficient for 24-2500 sq ft, when properly ventilated, insulated, and proper run times through the on-off cycles.

I'm not saying you don't know what you are talking about, but I'm telling you he does....


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## Hogwild80 (Jul 2, 2012)

Hey if it works for you so be it, not wanting to ruffle feathers just trying to help, but yeah I know what ya mean I'm a commercial Refrigeration,HVAC installer/ technician hey if it works for you keep on trucking.


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## Jeff C. (Jul 2, 2012)

Hogwild80 said:


> Hey if it works for you so be it, not wanting to ruffle feathers just trying to help, but yeah I know what ya mean I'm a commercial Refrigeration,HVAC installer/ technician hey if it works for you keep on trucking.



There is a such thing as oversizing a unit also....


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## Hogwild80 (Jul 2, 2012)

Oh yeah no doubt,but on the other hand if it was oversized it would pull down temp real quick and bounce on and off frequent.Like saying if you had it set on 73 it would pull down to 73 and shut off, but if it was undersized it would run and run and run and still not pull down to temp.But if your happy with your HVAC guy that's all that matters.


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## Jeff C. (Jul 2, 2012)

Hogwild80 said:


> Oh yeah no doubt,but on the other hand if it was oversized it would pull down temp real quick and bounce on and off frequent.Like saying if you had it set on 73 it would pull down to 73 and shut off, but if it was undersized it would run and run and run and still not pull down to temp.But if your happy with your HVAC guy that's all that matters.



Absolutely, therein lies the problem, on and off cycles too frequently = inefficiency, I rest my case. Have a good evenin


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## Hogwild80 (Jul 3, 2012)

Jeff you don't have to beleive me bud no nd to get piffed, that's fine but I know what im talking about if you don't beleive me talk to any random AC company and ask not needing to boast something you have no knowledge of have a good summer hope your ac does good, electricity is high when it runs continuously.


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