Anyone every install their own attic fan?
 

I want one, I have a pre-wired blank plate exactly below where I would think an attic fan should go. How hard of a job is this? Anyone done it?

No real big deal. Cut hole with circular saw or sawzall, leaving plenty of extra shingle to trim later. Install fan in hole, flash, trim shingles and seal/nail down. I need to put one in, but my roof is 40 ft high and steep. Yeah, I'm a big sissy when it comes to heights.

Don't cut a roof truss like the PO in my house did.

Are we talking whole house fan that vents to the attic or a fan to aid the gable and ridge vents?

I'm looking for a ceiling mounted fan that's flush with the ceiling and draws into the attic. The way I see this project is, get the fan, cut the ceiling, and then wire it up?

That's a whole house fan. Most will require cutting at least one ceiling joist and heading off at each side. It can be wired to a switch, timer, timer switch or t-stat switch. Be sure to wire in a cut off switch for safety.

If it is a pre-made roof truss, common in the midwest, the bottom member of those things are under tension.

If I were doing it and it required more than the rafter spacing (24"??) I would build a box and mount it on top of that.

On mine it looks like the guy wanted it centered in the hallway, cut the truss and put some 2x's in like a header. Looks like they pulled out 1/2 inch.

Yeah, I'd not cut a truss. But, there should be a bearing wall near the hallway where most of these things are installed. The other way to look at how forces affect a truss is to think of them holding the roof up and not always just holding the ceiling span. Still, the bottom chord is in tension, as you say, and must be tied.

basically, not knowing what a "truss" is I'm already in over my head :)

You indeed may be, but there is an alternative.

There are whole house fans which fit inside of the trusses and use multiple smaller fans rather than a large one. They have insulated mechanical lids which open and close when you hit the switch.

Its easy and a very good mod to the house. Bought it at Home Depot with a discount and a friend of mine and I installed it in a morning. Biggest hassle was finding 110v AC in the attic (it had 220vAC for the A/C) and sweeping up the insulation that fell out of the hole.

I put it in 4-5 years on and it runs all the time when the temps are under 100 over here. Its on right now, when I would otherwise have the A/C turned on as its in the 90's over here.

There was an "Ask This Old House" That covered exactly this. Can't find it on their site tho.

That's the easy part for me, the builder left me 110V wiring in the exact spot you would put the fan.

Get a variable speed one, not the three speed one. If it's near your bedroom door, run romex, or metal flex to another location away from your bedroom door. Put it near the kids room. They work well, I used to have one in my old house. Make sure a window is open, or you'll pull the ashes out of the fireplace as it tries to pull air into the house.

Scott,

Hugh is spot on. Mine is a two speed and there are times I would love to have a three speed but thats life.

Another thing to look at is to install a timer switch on the fan, so that you can turn it on and have it run while you are sleeping, yet turn off in the middle of the night when not needed.

Joe

I don't have any kids yet, but I'm trying.

It does cover up the "moaning sounds" very well... :)

If you install one make sure you have adequate venting out of the attic. Gable end , or roof vents. Ive seen installations where the CFMs on the fan was way to high for the attic vents.

I bet I don't, my soffets are vented, that's about it.

I have installed one of these:

http://www.wholehousefan.com/PRODUCTS/HV1600-GR.html

In two houses now. They make more sense than a high flow fan that is poorly insulated (you cover the attic side in the winter ideally) and cools the house immediately with air exchange. Once you shut the big ones off because they are so high flow the CONTENTS of your house heat the air back up.

The fan systems on the site above use little power - lower flow - and can run as long as you want - which cools off the entire contents (furniture, floors, walls etc) of the house by morning.

They fit is smaller framing too. I would have gotten a bigger one that has the fan further into the attic if I know I needed a bigger unit to match the performance in my smaller house.

A gable vent isn't hard to install either.

Being a cheap skate I use the fan till the humidity gets high. It does suck a lot of crap into the screens.

The whole house fan is what This Old House installed.

If it does not vent to the outside you are inviting mold in the attic. Especially if it is a bathroom/ shower fan. I have an old house (50's) and they did not outvent it. It cost me a fortune to remediate the mold we had. Once it was vented to the outside all was well.

You need cross-ventilation. Soffit to ridge is best. Vents 'High' in the gables would help, if you don't have a hip roof.

IMHO you should fix the attic ventilation before installing a fan.

For the whole house fan, you MUST have adequate outventing/exhaust of the attic.

Otherwise you are just wasting your time putting the fan in. Without enough venting/exhaust, the fan won't do anything but make a bunch of noise.

BTDT. I thought I had enough venting, but it wasn't. When I had more vents in the roof installed, the difference was night and day with the whole house fan.

Whatever fan you buy, it will give the minimum specs for square footage of the venting.

I installed a whole house fan about 6 or 7 years ago and I think it was one of the best investments I've made. I rarely use the A/C anymore (only when it's 100+) as the whole house fan cools the house and is much more comfortable than A/C and is way cheaper on the utility bill. But, when it's over 100 degrees, the whole house fan is like turning on a hair dryer.

My thoughts:

Detailed installation instructions are usually included with the fan - I followed then and the entire project took a few hours.

Get the biggest fan you can fit and afford. My house is 2100 sqft and I got a fan that is rated for up to 3500 ft. The larger fans are quieter and generally have more options (i.e., multi speed, belt driven, etc.)

You need to find a good spot for the fan. Preferably, the center of the house and not too close to bedrooms or living areas (ie., family room). This is because you don't want to be hearing the fan while sleeping or watching tv. A central hallway is best.

You need to check out the attic before purchasing & installing. The fan requires some space over it, so you don't want to cut a big whole in you ceiling only to find out that there is a/c ducting right there.

Your attic must have a minimum amount of venting. This is because the whole house fan will be pumping a large volume of air and it needs a way to escape the attic. If you don't have enought venting, the fan will blow fuses as it overheats trying to move air. The fan details will tell you how much sq. inchs of venting you will need - it won't be a huge amount but may be a combined venting of 1.5' x 1.5'. Think of it like running your car a/c on high but closing all the vents - the blower is strained.

To install, you will have to cut a whole in the ceiling - depending on the size of the fan, mine was 3' by 3'.

Once you cut the whole in the plaster/drywall, you will probably expose ceiling joists (the beams that the sheetrock was mounted to. The fan will require a perfect 3' x 3' square hole without any beams in the middle.

In addition, the fan has to sit a few inches above the hole to make clearance for the louvers to open & close. This will require you to build a frame out of 2x6's that will allow the fan to sit on top of the frame and leave room for the louvers. This is actually pretty easy to do and took me a few hours to completely install everything.

You will need an electrical source. I tapped into a junction box that was in the attic. You will have to install a switch - it is reccomended that you install the switch in a secure location so that kids do not accidentally turn on the fan. This is because windows need to be cracked when operation the fan. If the house is completely sealed up, the fan can suck air from the fireplace as well as soot & ashes.

I reccomend a fan that is belt driven. That is, the motor is a couple of feet away and connects to the fan with a belt - these types are quieter than a direct drive.

Check to see if there are any utility company rebates. My fan was about $300 and I got a PG&E rebate of $500, so I made money on the deal.

If you are not capable of installing yourself, you can ususlly get them installed for about $500. My parents had theirs installed from a ceiling fan company.

just install a ridge end attic fan at the end of youre attic should sit flush against mesh and you can screw it or nail it against any studs , the best fan for an attic is one that will keep the circulation and the hot air moving out of the space not ones centered that will just move the air around the room, the best disapation method is moving it directly out

yup, it's a 2 1/2 beer project.


stuck one in the garage as well, it helps remove bad odors