Passive Window Fan?

[Lost_in_the_HTTP]

Maybe passive isn't the right word, but one that doesn't burn power. I have a large window at the top of the stairs. Opening it elicits decent airflow as long as I have doors and windows open downstairs. I used to set a 20" box fan in the big window until I realized how much power they burn.

I've never seen low voltage or battery fans big enough to move any amount of air over a wide space.

Is there such a thing as a window fan that doesn't burn AC?

 

[herm0016]

how do you expect to get energy out of nothing?

and a box fan is like 50-60 watts. not much power at all.

 

[MtnMan]

Maybe passive isn't the right word, but one that doesn't burn power. I have a large window at the top of the stairs. Opening it elicits decent airflow as long as I have doors and windows open downstairs. I used to set a 20" box fan in the big window until I realized how much power they burn.

I've never seen low voltage or battery fans big enough to move any amount of air over a wide space.

Is there such a thing as a window fan that doesn't burn AC?

That is something you were probably taught in a basic science class in school. It's called convection.

A fan doesn't use electricity?

 

[Greenman]

The way to make that work is to build a chimney off of the window. Get it two feet above anything within ten feet of it and you'll get a little air movement.
Probably only cost as much as running a fan for seventy or eighty years.

 

[lxskllr]

Speaking of chimneys, I saw one once that had black metal panels at the top. Since It was just some old random house, and I didn't know the people, I'm speculating that it was made to heat up in the sun, and create a draft pulling air out of the house. Pretty clever way to use free energy.

 

[paperfist]

The way to make that work is to build a chimney off of the window. Get it two feet above anything within ten feet of it and you'll get a little air movement.
Probably only cost as much as running a fan for seventy or eighty years.

Do you have a drawing?
What about a passive fan?

14 in. Mill Aluminum Internally Braced Wind Roof Turbine

 

[Greenman]

Do you have a drawing?
What about a passive fan?

14 in. Mill Aluminum Internally Braced Wind Roof Turbine

I have a lot of trouble believing that those things actually increase air flow. Wouldn't shaped intake with a sail on it work better at directing air flow into an attic?

 

[paperfist]

I have a lot of trouble believing that those things actually increase air flow. Wouldn't shaped intake with a sail on it work better at directing air flow into an attic?

Probably but I've never seen a sail fan

I use something similar to these in my window:

Powr-Flite® F5 Deluxe Axial Carpet Dryer (1/4 HP) - 3,000 CFM

This Powr-Flite® F5 axial fan is a great axial carpet drying fan for the cleaning professional. A low electrical draw of 2.2 amps allows you to daisy chain 6 fans together off a single outlet. 3000 CFM. 1/4 HP. Stackable. 1 year warranty. 2 speed.

www.cleanfreak.com

They move 3000 CFM and draw 2.2 AMPS

They're floor drying fans. I'm not lying when I say it'll pull all the cool air from the first floor up to the second floor in minutes. Some day I'm going to rig one up between floors to pull up that cold cellar air to the 2nd floor. They are loud as hell though. I think you can rent them at Home Depot if you want to try.

Actually, they make 'level to level transfer' fans. Not sure if they're more energy efficient.

ASLL - Tjernlund ASLL - AireShare Level-to-Level Transfer Fan (Hard Wired)

Tjernlund ASLL - AireShare Level-to-Level Transfer Fan (Hard Wired) - Move air from Level-to-Level. This unit can either blow air up to a higher level or, when installed in the opposite orientation, down to a lower level. Move stove or fireplace heat up or down a level or move cool air from a...

www.supplyhouse.com

 

[sdifox]

I have a lot of trouble believing that those things actually increase air flow. Wouldn't shaped intake with a sail on it work better at directing air flow into an attic?

Err those are roof exaust. To let the hot air out of the attic. Problematic since eventually it will stop spinning due to wear.

 

[Greenman]

Err those are roof exaust. To let the hot air out of the attic. Problematic since eventually it will stop spinning due to wear.

I know.

 

[Paperdoc]

The only PASSIVE kind of window venitlator is .... an open window. Fully open, nothing in there to impede air flow. Then you are using FREE WIND POWER! - if there is any, of course.

 

[sdifox]

The only PASSIVE kind of window venitlator is .... an open window. Fully open, nothing in there to impede air flow. Then you are using FREE WIND POWER! - if there is any, of course.

Two similarly size windows open on opposite side of house works best, assuming doors are open of course. I prefer open windows to AC, unless it is really humid.

 

[Lost_in_the_HTTP]

That's what I do and with the upstairs window, the chimney effect is in play.

But sometimes I want even more flow.

 

[herm0016]

That's what I do and with the upstairs window, the chimney effect is in play.

But sometimes I want even more flow.

Then you have to use energy to do it. Thermodynamics is a bitch.