Whole House Fan

In the middle of summer, the second floor of our home gets unbearably hot and humid. Due to the shape of our home's roof (Mansard) it cannot be adequately insulated. I've already installed an Air Conditioning unit that is over sized for the square footage of our home to no avail.

I started looking into Whole House Fans (hereafter WHFs) and as another option, but upon further research found that they needed to vented into an attic space, or outside the home. Because of our Mansard roof, and the floor plan of the second floor neither of these options was possible. We did, however, have a narrow door into the attic of the garage at the end of the hall. This was enough to set my plan in motion.

I did some research on WHFs and found information online regarding sizing the fan to the square footage of your house, pricing, *CFM (Cubic Feet per Minute), etc. I found that I needed "X" amount of CFM for my home and did some online shopping for WHFs.

STICKER SHOCK....WHFs are expensive. While digging around online I stumbled across Drum Fans. These fans are typically used for moving air around workshops, so they're pretty capable of producing gale force winds. I also found that, on average, the drum fans have a higher CFM rating than any WHF with the same blade diameter, and they were 1/3 to 1/4 the price. So I started shopping around for a suitable Drum Fan that I could convert into a WHF. I spec'd one online that moved 2,000 CFM more than a suitably sized WHF, but being "Mr Instant Gratification" I looked for one locally and luckily stumbled across local hardware store that was out of stock, but had a floor model that they'd be willing to sell for less - so I was now at 1/5 the price of a WHF.... BONUS!!!

Step 1 Parts and Equipment

Things I bought:

• Drum Fan ($110.00)
• 2 Plastic Outlet Boxes($0.89 x 2)
• 1 Light Switch and wall plate ($2.00)
• 1 Outlet and wall plate ($2.00)
• 15' 14/3 Flexible power cord (this feels like a really thick extension cord - $8.00)

Things I already had on hand:

• Lumber (I used what I had on hand, but 2" x 4"s or 2" x 6"s and possibly even 1" x 4"s would have worked)
• 1/2" plywood (had some scraps handy)
• 3 Door Hinges (liberated from an old door)
• 2 - 3" x 3" angle brackets (had some laying around)
• Wood Screws (I always have these handy)

Tools:

• Drill
• Spade Bit
• Screwdriver Bit
• Scroll Saw or Rotozip/Dremel (for cutting the circle)
• Chop Saw, Circular Saw, or Hand Saw
• Screwdriver
• Pocket hole jig, screws and accouterments (not necessary, but I used it because I had it)

Total cost came to around $125.00, but that's because I'm a pack rat, and keep things from other completed projects....sometimes even wood scraps.

Comments

[Exposure101]

Very nice man! Thats why instructables is awesome!

[colincox1]

I agree, great idea,

I will be doing something very similar. and I have a 1 & 1/2 Story addittion to our house that is a self contained home. The roof is tin, and I guess is not too well insulated, I was planning to put a cavity using drywall over some insluation and using small computer fans (12v) and some PV solar panels to run the fans whenever there is light, any thoughts?

[CementTruck]

@colincox1,

Thanks for the shout out.

I don't know how many computer fans you'll be using, however, PC fans don't move that much air, and so you'd need a lot of them. There are solar roof vent fans that move a little more air (CFM) . The drum fan I installed, however massive, makes the indoor temperature more tolerable, but not as much as I had hoped, or expected.

Depending on where you live, how much sun you get throughout the day, your budget, and a few other factors, the first thing I would suggest is insulating under the tin roof. This will probably be the best bang for your buck at cooler indoor temps. You would need a gap between the underside of the roof and insulation for airflow, as well as a way for that airflow to be refreshed continuously.

[colincox1]

Cement truck,

Hey BIG thx, I had thought abot air flow CFM, but now you have made me think more I was thinking to have quiet a few, but as you said, need to understand the CFM better. The roof is insulated some, I do not want to take all what I have of a ceiling down to find out, I was just going to re insulate with batten cavitity with insulation. But the solar roof vent fan sounds good, your points about air flow with insulation is a good remindered for us all as it is often forgotten. PS based in mid OHIO, not the hottest of places, but hot enough for action! :-)

as for the drum fan, I am definitely, due to you , going to do that. just really like the idea of learing out large volumes of heat quickly, then suplement with specific a/c when you want to, than as you said, putting some ac on all day.

thx again.
Rgds Colin

[kidproquo]

This turned out very well. An even cheaper alternative is to use an attic exhaust fan (Amazon has them for about $50). Probably would not move as much air as your setup but for those without quite so dire needs, it should work!

[CementTruck]

Thanks kidproquo.

I already had an attic fan. You're right, it didn't move enough volume, so I had to improvise with this monster.

[bowdenja]

When I was kid we didn't have A/C , we use an atic fan, this while living in Florida.

Man that thing sure made the curtains stand straight out. Seems like that was the best sleep I ever got.

Good instructable and idea!

[CementTruck]

Florida without A/C? Whew!

I used to live in Eglin AFB/Ft. Walton Beach a couple of lifetimes ago, and as far north as that was it was still pretty warm. I miss it though. I also lived in a tropical country for 16 years without A/C and it didn't seem to bother me then. Ocean breezes make a BIG difference. Thjs mid-west heat and humidity sans breezes are a whole 'nother issue though.

Thanks for commenting.

[trbotnen]

Are you worried about backdrafting? If you are forcing air out of the house through a fan, it could cause carbon monoxide from your furnace to be sucked backed indoors. Other than that, this is a great 'ible.

[CementTruck]

That's a good question. I'm no expert so I couldn't tell you for sure, but my furnace has an electric version of a "pilot light", so there isn't a flame burning all year long, and since this fan is only used in the summer the furnace isn't used at the same time, so I'm assuming I'm safe. I should probably be worried about Radon being sucked throughout the house though.

Another thought too would be the fact that whole house fans even exist, and are sold daily.

I'll have to do some research and get back to you on this. This was just my gut instinct.

Thanks for commenting.

[CementTruck]

Thanks Sunshiine! Please vote if you get the chance (Epilog).

[sunshiine]

I could use this idea! Nice ible! thanks for sharing!