# Whole house fan



## maverick06 (Apr 7, 2010)

Hi All,
  I grew up with a whole house fan, boy did I miss it when I moved! I am now about ready to install one in my house and am looking for some tips. 

I already have ordered the fan, 






30" fan blade
Belt drive
34" x 34"
5700 CFM
1/3 HP, 525W High, 4.1 amps - 400W Low, 2.8 amps
2 speed wall switch
Cools 1900 sq. ft. max
34-1/4" x 29" shutter opening

I will end up running some new wire to the attic space for it. Thats a hassle, but not a big deal. I am looking for tips for instalation. I am suppose to cut a joist for the instalation. i am a bit concerned about that. The house was built in the early 1950's with 16" center joists.  Most places i read say to just cut the joist then frame it out. That doesnt sound right. Any suggestions! Sure dont want to cause any nail pops or worse doing this. 

Also any tips to minimize the vibrations?  Or tips in general?

I love having a whole house fan, but have never put one in before. 

Thanks
Rick


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## vvvv (Apr 7, 2010)

Support the joist/rafter you're cutting with 2 2x4 pieces screwed to the nearby rafters so when you cut the rafter it wont sag.


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## fbelec (Apr 7, 2010)

the way that i've seen them done is cut the joist. cutting one joist won't be any support problem. then use the same size lumber as to go from the the joist on either side of the cut one. nail to those two joists with a double piece of 2 by what ever size the joists are 2 x 6 or 2 x 8 or 2 x 10. do this on both size of the cut joist and nail the cut joist to the cross pieces you just put in. thats it. there is nothing you can do if the fan has a vibration or hum. normally they use a motor that is quiet. and as you know the fan blade makes enough noise that you wouldn't here the motor if it was humming. as far as circuitry for that fan, depending on the size it is, as in the amount of air that it pushes, will take anywhere from 4 to 8 amps. you can get by with a existing bedroom circuit if it takes 4 amps but if it takes 7 or 8 amps depending on the circuits existing load you might have to run a new circuit. a 15 amp circuit will be fine. if you have to run a new circuit the code is that the circuit be arc fault type. and the arc fault breaker should be the same brand as your circuit panel. 
oh, make sure that you have sufficient attic venting or the fan will make more noise than it should and won't push the air that it should also. i've seen it happen where the fan got installed into a small vent or ventless attic and didn't work right or not at all. if there is not enough venting to compensate for the air that the fan is pushing you will get a certain amount of air feed back thru the fan that you get air from the attic into the living space. you'll be able to tell. on a hot day run the fan. if you have feedback air you should be able to smell it. it will smell like your hot attic in and around your fan. good luck. whole house fans are great.


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## fbelec (Apr 7, 2010)

btw if you didn't have one on you old fan there are companys that make a thermostat for whole house fans so if it were to cool the house off to much it would shut the fan. i've seen the on some older fans installed but i have not done the install so i don't know the brands. i could make one but it might be hard to explain. 
if you see one of these thermostats get it. well worth having for over night runs. by the time you wake up it's so cool you don't won't to get out of bed to shut it :bug:


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## maverick06 (Apr 7, 2010)

Thanks for the input. That was my plan, its surprising how many manuals differ (I have been reading online) Most do not have  you make a bridge piece. Most do not have you use double headers. Most dont have you reinforce the remaining joists...... I plan on doing all that though... wood is cheap. Do it right the first time. Thanks for the input. I am thinking about (prior to instalation) Welding together the bolted frame and taking the propeller blad off and balancing it. I have a MIG welder in the garage and balance my RC airplane propellers, so that should help minimize some vibration. it should be easy to do and a little effort ahead of time might save a lot of agrevation later. 

I have been looking for a switch that lets me select speed and hours to run, cant find it. The fan specifies no rheostats either. Unfortunatly the box I plan on putting the switch in is only large enough for a single size switch, but I have to run new wire (high/low/ground/neutral). 
Thanks for the input

Rick


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## Tony H (Apr 7, 2010)

I don't know if anyone mentioned it but before you cut the joist but haver it measured and marked put a 2x4 across the span where you are cutting to take up any load and keep it aligned while you build the inner frame.
The other thing for vibration isolation between the fan frame and mounting install some hi density foam it will help a bit.


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## fbelec (Apr 7, 2010)

tony i'm not sure of the foam your talking about, but wouldn't the foam get eaten up from the vibration of the fan?
i've tried a tire tube between a noisey bath fan and a joist and there was very little difference. if it's vibrating and the foam gets eaten wouldn't the frame rattle?


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## maverick06 (Apr 8, 2010)

I've thought about that.... rubber may help better than foam. I am inclined to think that if I install everything with screws, not nails, that should prevent vibrations... And making sure everything is very tight together should help.... I think.... 

It will make noise regardless, but I would like to go in making the best decisions I can. 

Thanks for the input so far!


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## semipro (Apr 8, 2010)

I've installed and used a few of these.  A few thoughts: 
- If you're installing in a hallway the walls on either side will likely support the joists well.  You many not need to worry about the one you cut for louver clearance. 
- Belt driven fans like the one you chose are really good about not vibrating.  I wouldn't worry about vibration unless you experience it.  
- A timer or thermostat is real nice on one of these.  Its better to get up in the morning with this thing already off. 
- Find ways to latch your bedroom doors open.  When this thing is running and a window is open in a room the door can slam shut and knock you out of bed.  
- Consider filtering the air entering the house though windows.  The airflow created by this thing will bring in a bunch of dust.  
- Make sure you have adequate attic ventilation either by continuous soffit vents, gable vents, or ridge vents. 

Good luck.


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## Czech (Apr 8, 2010)

Does anyone know if these can be mounted through the wall? I've always thought one of these would take care of most of our cooling needs during the summer months, split level upper floor is all open with cathedral ceiling, thought one up in the peak through the wall may be a good investment? If so, are they filtered at all?


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## vvvv (Apr 8, 2010)

Czech said:
			
		

> Does anyone know if these can be mounted through the wall? I've always thought one of these would take care of most of our cooling needs during the summer months, split level upper floor is all open with cathedral ceiling, thought one up in the peak through the wall may be a good investment? If so, are they filtered at all?


The science of this application is simply to create a wind in the house so you feel the cooling effect. The fan should be located centrally enough so that it draws equally from each opened window opened so to feel the breeze & yes you can install an exhaust fan anywhere but exhausting to the S & inhausting from the N sounds more ideal. Factors to consider are indoor temp vs outdoor temp, outdoor pollutants & pollen +, etc.? A well insulated/vented attic doesn't need mechanical ventilation I think.


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## fbelec (Apr 9, 2010)

you wouldn't want to put one of these in your familyroom. they are to big and loud. they not super loud but because they're 30 inches square they make a lot of wind noise. and in the winter it would be a source of great draft. these are made to be installed in a central hallway location. they are great. makes it seem like a breezy night. 
there is no way to filter the air that comes in unless you put filters in every open window or door.
if you are just one person or a couple it might be cheaper to run a small window air conditioner. air conditioner 5 amps when the room reaches temp the 5 amps drops to about 1 amp. until the temp in the room goes up and then 5 amps again until the room cools
running the fan all night or say 5 or 6 hours might be more electric burnt. the fans that i wired are in the 5.5 to 6.8 range constant draw until shut off.


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## Czech (Apr 9, 2010)

It just dawned on me, call me thick. These push air OUT! Now I got you! Could not figure out why you'd want all the hot summer attic air in your house.....


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## LLigetfa (Apr 9, 2010)

If you look close at the inside trim, you can see there is a notch in the middle.  This is to allow the joist to be notched out slightly and not cut out entirely.  The fan is then mounted above the joists in a boxed curb.

To eliminate vibration sound travel through the joist, you could hang the boxed curb from the rafters and couple it to the joists with EPDM rubber.


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## semipro (Apr 9, 2010)

I believe the motor on this unit is isolated with rubber mounts and since its driven by a belt, vibration is minimal.  We've used a similar unit installed in a hallway and vibration was not a significant issue.  The units that are direct-drive are much more prone to vibration.


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## woodsmaster (Apr 10, 2010)

If you cut a cieling joist, by code you are suppost to double the joist on each side of the cut one. The boards supporting the cut joist should also be doubled. You may want to consider an insulated hood to cover the fan in the attick to control unwanted heat loss in winter.


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## Hunderliggur (Apr 10, 2010)

Just make sure if you cut you are cutting a joist, not a truss.  Trusses do not like to be cut!  If there are diagonal braces from the "joist" to the rafter, attached probably with flat plates, it is a truss.


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## fbelec (Apr 11, 2010)

woodsmaster said:
			
		

> If you cut a cieling joist, by code you are suppost to double the joist on each side of the cut one. You may want to consider an insulated hood to cover the fan in the attick to control unwanted heat loss in winter.



yep thats right those things are like leaving a window open a crack. easy to make. 2 inch foam panel, glue, done.


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## maverick06 (Apr 16, 2010)

Well i got it installed! 

I ended up having to cut 2 joists. I believe I framed it out pretty well. Boy the old joists in the attic must have been made from endagered hardwoods back in the 50's Had to use a lot of screws becuase a lot of the attempted naiils just bennt on the first hit! The fan works well, the manual says not ot use a rheostat, the switch has a high /low setting though. High produces a modest amount of noise, rumbly, not a typical high speed fan noise. The low speed is awesome and really quiet! I have a split level and was unable to install it in the upper hallway due to stuff in the attic, but installed it on the center level, workes great, pulls a lot of air. The fan is quite nice (4 blades, not 6 though). I will have to build the foam box before winter though. 

I now have to figure out a way to latch the bedroom door open about 2 inches... enough to allow for airflow... but not enough for the cat to get in! but one thing at a time. This is great, i really expect for it to make a wonderful difference (I grew up with one and am excited to have this in the house)! 

The installation wasnt fun... but it is in. I am also pretty confident that the house is massively overbuilt...  should really help keep us cool without running hte AC. On high it pulls 530watts, and on low it pulls 390 watts. That is really cheap to operate! The centeral air is on a 40amp breaker.... and a window AC is about 1200 watts. While those would cycle on and off this is definitly the eay to go, at least for where I live in the country!






















Rick


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## fbelec (Apr 16, 2010)

nice job. looks like it's around cthe corner from the bedrooms. that should be good for sleeping


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## daveswoodhauler (Apr 16, 2010)

Placement is great as well, as you are going to pull up the cooler air from the lower level of the house.
Looks cool.


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## vvvv (Apr 16, 2010)

I'm wondering if you have enough gable venting to suit the fan's cfm. If not the attic will become pressurized & push the heat down?


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## LLigetfa (Apr 16, 2010)

To latch the door open, you need a door stop that holds in both directions like this.





...or one of these.


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## maverick06 (Apr 16, 2010)

BLIMP said:
			
		

> I'm wondering if you have enough gable venting to suit the fan's cfm. If not the attic will become pressurized & push the heat down?



Oh, no worries there. Lots of attic space, so there are 2 gable vents and soffet vents. Arguably there might not be enough venting space there, but the entire roof has a ridge vent (70 to 80 ft)! So that should be massively adaquate. Thanks for making sure of that, it wouldnt be any fun to have that problem! 

Love the ideas to stop the door halfway! I will have to see if homedepot has something like that! 

Already had it on for about 30 min today, so nice. Today wasnt for cooling the air, but just bringing fresh air in. 

My wife is excited too, apparantly the matha stewart magazing just had an article saying a whole house fan can save up to 90% AC costs (my guess is that is awfully generous where I live), but point taken, its cheap and socially acceptable. So thats good! Might think about seeing if you can find that article if you are interested in selling the idea to your other half!

Thanks a lot for the assistance guys!


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## begreen (Apr 16, 2010)

Nice neat job down below, now get some staples in that romex and neaten it up in the attic. Seriously, those loose wires can be a hazard and are not to code.


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## fbelec (Apr 17, 2010)

LLigetfa said:
			
		

> To latch the door open, you need a door stop that holds in both directions like this.
> 
> 
> 
> ...



very nice door stops. where did you buy them?


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## maverick06 (Apr 17, 2010)

BeGreen said:
			
		

> Nice neat job down below, now get some staples in that romex and neaten it up in the attic. Seriously, those loose wires can be a hazard and are not to code.



HAHA I knew I would get called on that. I measures and left enough slack to properly attach the romex in place. I also have to straighten up the insulation. But it was about 11:30pm when I left the attic) The house was built in the early 50's (not knob and tube, not sure what the black stuff is called). so 90% of the wires are laying across the joists, under insulation, etc.... rewiring isnt an option, so it is what it is, but for the newly installed items I always do my best to insure they are done right. 

I wasnt at all happy with the electrical aspect to the fan, the "junction box" that all the wires were to be fit into was about 2"x2"x2"It was too tight for easy work. But was able to get wire nuts on and electrical taped the nuts on and everything in place. 

Thanks for calling me on that! Seriously, its important, but i have every intention of doing that tomorrow. 

Thanks
Rick


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## fbelec (Apr 17, 2010)

black stuff is a early version of romex. back then ground wire was a option. some had it, some did not. next time your up there remove the tape. if you did the wirenuts right there is no need for tape. but the big reason for removing the tape is between the heat in the attic and the heat the motor makes the glue from the tape starts to liquify and gets into the splice and acts like a insulator. and soon enough the splice will fail. seen it happen alot in attics.


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## Cluttermagnet (Apr 19, 2010)

Congratulations on the new fan. We have one, and I like it a lot. There's some truth to the idea of summer A/C cost savings. Trouble is, this works best for me if I wait until around 3-4AM when it's hit the coolest overnight temperature, before turning it on, then run it several hours, then turn it back off as the sun resumes heating. During this short 3-5 hour window, you might see a significant drop in inside temperature from the heat rise from the previous day. We do. The strategy is to wait until its a few degrees colder outside than inside. This could be put on a timer, BTW, but I also play some games with opening strategic windows only for the cooling times, and otherwise keeping them all shut to avoid daytime heat gain through open windows. OK, so I'm a night owl and crazy enough to do this.  Most folks who work day jobs will roll their eyes, but let me tell you, this actually works great!. Last summer I ran almost no A/C at all, the whole season- and didn't suffer. Houses have tremendous thermal equilibrium. It often takes a week or more for inside to begin to really catch up with high outside temperatures, using this strategy.

Run it during the day a lot and you are sucking in lots of warm, humid air. Yeah, you get the nice breeze effect, but you also get heat gain. Lots of it. Then turn off the fan and you feel hot- because you have heated your house with all that outside air. If you run a whole house fan constantly on High, you are probably pulling a similar amount of current compared to one or two window unit A/C, FWIW. (Remember- duty cycle on A/C) We used to run ours on High near continuously, sometimes for days or even weeks on end. You'd see that in your electric utility bill for sure. Now I run only a few hours a day and get much less temp rise in my house.

These things might not work the same for you. I'm on a wooded lot with lots of tall trees, many over 100ft. My house is in pretty much full shade in the summer. If you have full daytime sun exposure, all bets are off so far as my method. Experiment.

Something I doubt anyone else will think of- if you are a wood burner, remember that accidentally (or intentionally) turning on the fan while you have your wood stove going could lead to some smoke in the house. I had a little one time. I advocate a 'seasonal kill switch' in addition to any 'regular switch'. Or, in my case, I unplug the fan up in the attic and also reinstall some removable winterizing to eliminate the big winter heat leak the fan causes. I built a 5-sided attic-side cover box out of pink foam wallboard. I pile insulation on top of that.


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## flamencogirl (Apr 21, 2010)

I agree with Clutter that whole house fans are great.  I also agree not to run it during the day - you can watch the thermostat increase.  My fan is probably 20 to 25 years old and I tend to run it when it starts cooling down at night.  I often wake up in the night and turn it off because I've gotten chilly!  I will then turn it on and run it for a couple of hours in the morning, before it starts to heat back up.  I live in an older house with no central air and I generally don't miss it.  I live in the mountains and it usually cools down well at night.  There might be about a week each summer that is really hot, but I can always cool down in the pool!   I've never really lived in a house with AC and don't regret it.  My fan is maintanence free, I've never done anything to it.  I've pondered from time to time getting a newer and hopefully quiter fan, but it always comes down to if it ain't broke don't fix it!


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## delaford321 (May 2, 2010)

What is the benefit to having a whole house fan? In what homes would it work best?


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## fossil (May 2, 2010)

delaford321 said:
			
		

> What is the benefit to having a whole house fan? In what homes would it work best?



Are you really here seeking to gain or share information, or are you here simply to spread your links around?  Just askin'  Rick


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## fbelec (May 3, 2010)

delaford321 said:
			
		

> What is the benefit to having a whole house fan? In what homes would it work best?



you run the one fan instead of running 7 fans. run more than two 20 inch box fans and you are using more power than the whole house fan. and the whole house fan moves about the same amount of air as 4 to 5 twenty inch box fans. and it can be put on a timer or thermostat to shut it down in the middle of the night when it gets colder. 20 inch box fans run about 2 to 2.5 amps each. the whole house fan that the original poster install runs at 5. so if your running 5 box fans it takes the same amount of electricity as a 12000 btu window air conditioner running full out. so doing the math if your running a load of box fans why not run the air conditioner and take out the humidity at the same time. actually it would be cheaper to run the air conditioner because the compressor will cycle on and off as needed. 
ok did i do a good job selling the whole house fan :cheese: now where is my commission


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## basswidow (May 3, 2010)

Growing up - we had a beach cottage down on the Northern Neck of VA.  It had a whole house fan.  You'd flip the switch and the curtains would draw in.  We'd prop doors with old antique irons.  If you didn't - the draft would pull the doors shut.  

It was rare that we ever ran the window units.  During the day - we were in the water and fishing.  There was always a breeze coming off the water.  At night - it would cool off quick.


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## Don2222 (May 29, 2011)

Hello maverick06

I just did some testing on my whole house fan.

It is 88 degrees F outside in shade and 94 Degrees F in the Sun and the attic is 109.0 degrees F.

After running the Fan on High for approx 3 mins the temp in the attic went down to 93.2 Degrees F

It is 85 Degrees inside!

*How is your fan working these days??*


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## Cluttermagnet (May 30, 2011)

Aren't the big ceiling fans just great? We love ours.

If you didn't get one of those self- adjusting louver covers with that fan, may I suggest that 1/2in grid wire cloth, spray painted white with Rustoleum, would make a very attractive ceiling fan cover without restricting the airflow much. You'd notice the fan a lot less, that way.


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## Don2222 (May 30, 2011)

Cluttermagnet said:
			
		

> Aren't the big ceiling fans just great? We love ours.
> 
> If you didn't get one of those self- adjusting louver covers with that fan, may I suggest that 1/2in grid wire cloth, spray painted white with Rustoleum, would make a very attractive ceiling fan cover without restricting the airflow much. You'd notice the fan a lot less, that way.



Thanks, that is a good suggestion Cluttermagnet

I do have the self adjusting louvres, just not in those pics. 

They do move alot of air!

I also installed a radiant heat shield in the attic using proper vents and reflectix foil. That takes the whole house temp down over 10 degrees
See thread
https://www.hearth.com/econtent/index.php/forums/viewthread/71142/P15/

Do you have one?


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## Cluttermagnet (May 31, 2011)

If I understand your question right, all we have for ventilation in the attic is those traditional roof peak vents- the triangular, louvered, screened ones at each end of the house. The roof on our Rambler is pretty shallow pitched BTW, maybe 30 degrees or so. We have no ridge vents or other such things. It's worth mentioning that the builder did put in a pretty good ~2ft overhang, and it looks like they built in some small spaces (slots) to let it breathe, way down at the end of each rafter space where they join up with the fascia(?) boards- the ones you attach the gutters to.


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