Whole house fan in Phoenix?

[hal1]

Yay or Nay?

- Not an attic an discussion.

Being very dry might make this an even better proposition?

100 degrees days now, but 70 at night. Would love to cool the whole house down to 70 so that everything is cooler in the morning and the A/C doesn't have to work as hard ( since the whole house fan helps cools the entire mass of the house)or come on as early in the day)

Anyone familiar with QuietCool Brand?

I know it's an easy install for many of you, but it's beyond my ability. What should I be asking the company I plan on going with?

 

[PoorOwner]

it works well if there is a large differential of temperature drop at night. However at 70 degrees I am not sure if it is enough for comfort. Your house will not be lower than outside temperature and probably a few degrees more. It works well here is CA with the exception of a few of the hottest days.

 

[ard]

In Phoenix, 70 inside is icy cold.


That picture looks like a cheap gimmick...I've installed a few. 30" or 36" square, BELT drive (not direct), as many CFM as you can get.

The more air moving in and across your bodies, the cooler it feels. Im laying in bed right now, its near midnight....it was 100F today, 67 now- fan on, will go for a few hrs before the timer turns it off.

One other key- attic needs to be adequately vented for the airflow. The whole house fan ***** air out of the living space and into the attic- you need to have enough vents in the attic to exhaust it. In Phoenix, this should not be a problem.... (In some cold climates you dont want -40F air flowing freely into the attic)

 

[Aquamoose]

Do it!

I did mine when I was living in CA. It's extremely helpful in bringing down AC costs by running the fan to pull out the warm house air AND push out the hot attic air before turning it on.

I bought the type that sits on the attic joists in the hallway. Got it from Home Depot. Cutting & mounting it was easier that finding a powered outlet in the attic. It turns on either by pull chain or wire it to a switch.

Again, do it. You'll come back here and thank me.


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[Aquamoose]

6000 CFM 30 in. Belt Drive Deluxe Whole House Fan with Shutter

http://www.homedepot.com/p/202067896


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[Williamtell]

With your climate you are in a perfect location to use it in the evening, overnight, and morning because you get a quick and consistent cool down after the sun set.

I have a new construction house in Oklahoma and literally had to argue with the builder to get a whole house fan installed. For decades they were standard features but after A/C became affordable they stopped installing them around here.

I love being able to open up a few windows in the morning and run it through lunch time on a 80 – mid 80’s day and get a nice strong breeze of fresh air through there to cut down on our A/C use from April - October. The biggest limitation around here (Oklahoma) is humidity, our temps are usually pretty nice but the humidity varies greatly. Some years there is very little, other years it feels like a swamp.

The unit we have is belt driven and from a big box store and moves plenty of air for our 2500sqft house. The only recommendation I would have is to put it in an out of the way ceiling because they can be loud; and get some foam board to cut to size and Velcro tape and make am easy on/off insulated cover for it during winter / heat of summer.

 

[Falcon67]

We'd have one here if I could fit it in somewhere. Especially good in NM and AZ I'd think. Swamp coolers in the desert make ice cubes, so simply moving air does wonders.

 

[theoldwizard1]

Whole house ATTIC fans works well because they not only pull the hot air off the ceiling in the living space, but pressurize the attic forcing the super hot air out !

 

[PoorOwner]

The manufacturer has some idea what CFM it should have per square footage of the home. Works out to be some big CFM from 3000-6000. I have used in a few houses now but they never have enough vents to flow the recommended CFM. They have a gable vent and couple of small one on the roof. If you do turn it on high, you will feel the a some wind coming out of the gaps like recessed lighting in the ceiling. Therefore I would recommend calculating how much ventilation you have first and just buy the smaller one if you don't plan on having new vents added.

In theory with the recommended size, on highest setting, lets you open alot of windows and they would blow in like gale wind, but then you need ALOT of vents on the roof / soffit or gables

 

[ducksface]

6000 cfm is a moderate sized ceiling fan on medium high.

 

[rattle_snake]

Allowing air to move from living space to attic is likely against fire code. Fire goes up...
5/8 drywall does nothing to contain flames when there is a hole and a draft, fan running or not.
I'm all about exhaust fans, I have several, but I would not vent to attic. Ventilate to outside. Vent attic by itself, to the outside on a timer. Most homes in AZ have poor to minimal attic venting.

 

[Git]

We have four of them and they do in fact work very well

These are a little different than your traditional, central 'whole house' fan that most people are used to

For one - the are a lot quieter because the motor hangs from the attic rafters - no vibrations are transmitted and the motor itself is several feet away from the vent opening

Also, keep in mind, they work best when you can create a draft across the area you want to cool. For example - we have one in our master bedroom and one in our master bathroom. You can tell when they are running, they make a low rumbling sound, but they really are very loud

Extremely simple to install - basically cut a hole in the ceiling and hang the motor on the straps in the attic. The only hard part is getting electricity to them and how to turn them on/off - you can even use a wireless z-wave type switch. (I have a z wave system that is programmed to turn them on/off at certain times)

I see that HomeDepot is even selling them now - it shouldn't be too hard to find a reputable installer

Have you used their dealer locator page?
https://quietcoolsystems.com/where-to-buy-whole-house-fans/find-dealer/

 

[ard]

Allowing air to move from living space to attic is likely against fire code. Fire goes up...
5/8 drywall does nothing to contain flames when there is a hole and a draft, fan running or not.
I'm all about exhaust fans, I have several, but I would not vent to attic. Ventilate to outside. Vent attic by itself, to the outside on a timer. Most homes in AZ have poor to minimal attic venting.

They are not.

Next!

 

[6768rogues]

Whole house fans are not in violation of the code here in NY, but they are required to be connected to a smoke detector so they shut down early in the event of a fire. Otherwise, the whole house will be gone before the fire department gets out of the fire house. Give your family time to get out in the event of a fire.

 

[hal1]

That picture looks like a cheap gimmick...I've installed a few. 30" or 36" square, BELT drive (not direct), as many CFM as you can get.

I've known that WHF's work, I just didn't know if there were any specific considerations in phoenix.

Oddly, there's next to no one here that installs them. - I know it's pretty simple but it's just ot in my Wheelhouse.

The model shown is from a company called Quietcool, and this seems to be a design that some companies use, has a damper in that box at the bottom. - rated at 48 decibells at 1 meter

I'm not in the business, but my brother-in-law (yes, the famous "I know someone who told me....) is an engineer, specifically, with a firm that engineers/designs/sells HVAC on a commercial lever. - think Trump towers (without regard to it being Trump) and companies in Jordan and such with large buildings going up. I've got to trust that if he says he likes this design then it has to be decent. (the pictured hanging vent)

Thank all. It goes in today

 

[nh_yota]

I really don't think you can go wrong with a whole house fan as long as it's one that seals up tight when closed. The shutters on the big belt drive fans do not seal well at all. I installed one at my brother's house about 15 years ago and every winter they need to put a cover over the shutters to keep the heat in the house. I like the ones with remote mounted fan or the large foam doors on top.

 

[ducksface]

Swamp box/evaporative cooler with the water turned off is now a whole house fan.
Lots of people have them(every house with a swamper), you just didn't know how their swamper works.
Get a piggy back ac unit. Ac, heat, Swamp, whole house fan, all in one duct system.
That's if you insist on a fan.
I'm guessing the new low seer ac units use very little electric outside of the actual fan.

Many. Many many nights don't drop to Temps low enough to use the fan. A 85 degree night is OK with me but is not what most folks call comfort. So you 'cooled the house' down to 85 degrees by using the fan....

 

[PFSard]

Thank all. It goes in today

I'm interested in your evaluation of this after it's been operating for a while. Good luck with this.

 

[hal1]

Windows half open or fully open? Which will clear the house quicker? in other words...

Which creates more volume of air being exhausted?

half open window - More pressure over a smaller area?, or
less pressure over a larger area?

 

[PoorOwner]

Windows half open or fully open? Which will clear the house quicker? in other words...

Which creates more volume of air being exhausted?

half open window - More pressure over a smaller area?, or
less pressure over a larger area?

Really doesn't matter. The cfm would be the same. You can play with it to see how the draft feels for you. Open the window in the rooms you want to cool down first. Just make sure the doors can't slam shut and you always have a backup window cracked open.

 

[ard]

The window is a resistance to flow. (as are hallways, doorways, screens, etc)

The smaller the opening, the less flow and higher pressure drop.

A fully open window WILL flow more air.

The CFM will NOT 'be the same' between the two.

The rest, I agree with:

You can play with it to see how the draft feels for you. Open the window in the rooms you want to cool down first. Just make sure the doors can't slam shut and you always have a backup window cracked open.

 

[hal1]

For overnight Cooling, I'd rather have greater volume than greater Breeze. That's where I didn't know if it made a difference.

 

[ard]

For overnight Cooling, I'd rather have greater volume than greater Breeze. That's where I didn't know if it made a difference.

Well, if you COULD keep CFM constant, a smaller opening will have a higher velocity- hence more breeze. But a smaller opening also creates more resistance, which means the CFMs will drop. Somewhat. Every fan has a specific curve that describes CFM versus resistance.

I did look at the product you purchased- and each model has a CFM rating that is done under a specific condition. This is an example of why the CFM 'rating' is quite different than you get when it is installed.

So just play around with the windows, see what works!

 

[EOC_Jason]

Wouldn't the back-pressure in the attic have a bigger effect on CFM than opening additional windows?

When I lived in houston we had a thermostatically controlled exhaust fan on the roof. While houston is too humid 99% of the time to open your windows, it did help with the attic temps in the summer and helps the A/C not having to work as hard.

 

[ard]

Wouldn't the back-pressure in the attic have a bigger effect on CFM than opening additional windows?

When I lived in houston we had a thermostatically controlled exhaust fan on the roof. While houston is too humid 99% of the time to open your windows, it did help with the attic temps in the summer and helps the A/C not having to work as hard.

Air flow thorugh this 'system' is analogous to current, voltage and resistance in a circuit.

The fan is a 'current source'. (But not a constant current source)

The current is the airflow

The resistance in the windows, the hallways, the attic and the attic vents are all additive. The larger the resistance the greater the pressure (voltage) drop at that resistance.

So you are (kinda) right- a marginally vented attic, just the bare minimums, will have a greater impact on the flow than opening 4 versus 5 windows.

BUT, given whatever is going on in the attic for a installation- once it is up and running, the opening or closing of windows will change flow. The owner will just be blissfully aware they are losing flow due to poor attic venting.

Agree on venting a hot attic. Many times the AC unit and all AC ducts are running in a 140F+ attic. (Some modern low E use homes actually create conditioned space for the ducts and HVAC system...)

 

[hal1]

I think I, surprisingly, have more that enough ventilation in the attic.

I opened up the ceiling panel in the garage, this now gave me over 4 feet of additional free air with the garage door open (it's one continuous attic from house to garage).

Using the shown method, there was no apparent change in air movement through my window.

Would this seem to indicate that I already have more air flow than needed, and that additional venting would be of no value for this purpose? I opened the attic ceiling door at the 40-50 second mark in this video.

Without the regard to how hard it SEEMS to be pulling, I modulated this strip with weight to start at low level - if were flying up then it would be more difficult to see any change.

 

[hal1]

[youtube]https://www.youtube.com/watch?v=V9l8UEHPHzk&t[/youtube]