Roof area used for room heating

[domwild]

Hi,

In areas of the world, where the temperature range is in the order of 0 deg. centigrade to +30 it should be possible to extract hot air out of the roof space and blow it into rooms.

Ceiling must have good insulation and black tiles or black-painted tin roofs might just be OK.

System could also be built to extract hot roof air out of the roof and room area during heat waves.

Does anyone have had some experience with a system like that??

[wdyasq]

domwild,

Do you realize there are even formulas to calculate the amount of collector area! Why, it can even be calculated to found out if single or twin glazed panels are necessary.

There is something called a SEARCH ENGINE that can help you with it.  You may even find examples of houses done that way.  You may find the one of the thousands actually working with details on how they did it! Hell, you may drive by some every day! IMAGINE THAT!

The Internet is an amazing tool connected to your computer.  One only needs to use it.

Ron

[ghurd]

Might be something here.

http://www.fieldlines.com/story/2005/7/19/13842/8442

G-

[willib]

i think you mean the attic area ?

i've done that ,i currently have a 6" dia  flexable aluminun drier exaust pipe , going from the apex in the attic down to the inside of the closet with a fan at the top.

it doesnt work that well when it is real cold , but when the outside temp is 40 to 50 degrees farenheit on a sunny day i turn the fan on and open the closet.

it gets surprizingly  hot up there when the sun is out..

http://www.digitaldutch.com/unitconverter/

[domwild]

Ron,

I believe you misunderstood my request. When you speak of collector area, you probably mean commercially available solar air heater boxes attached to the roof. No! That is not what I am after. And thanks for telling a dumb Aussie that there is such a thing as the Internet.

I have only ever once come across a commercial system on sale here in Perth, Western Australia where the hot roof air is pumped into the living areas if the temp differential is more than 5 degrees C. But of course, this company is not giving much away in the form of pipe diameters, fan motor types and sizes, etc. This company is also thinking of blowing the hot air outside (of the attic space) in summer but that is their next project.

Any DIY person had any luck? Any drawbacks?

 

[domwild]

Ghurd,

Thanks for that. They are all talking about solar water heating; I am looking for room heating with ducted hot air from the attic. The fan motor controlled by something like a Picaxe PLC to sense temperatures in rooms and the attic and then drive the blower. Cooling of rooms by pumping out the hot air from the attic and rooms to the outside. Also PLC controlled. Just dreaming!

Thanks.

[domwild]

wiilib,

Thanks for that. Should I ever build another house, then I am going to use a system like that.

Thanks.

[elt]

Thanks Wilbur, I'd been thinking of this for a while and your post gave me both the nudge to do it and helps set a reasonable expectation on how much heat I might might get...

Since I had a 4" duct fan, I thought I'd try with that -

In the picture, it's 60 degrees cloudy/hazy outside and an the air exiting the duct is 80 degrees.

The fan is a "suncourt" available at Home Depot for a little over $20. It's listed as .25 amps and 80 cfm... is that enough info for someone to calculate BTU's? ... I searched the web for btu calculators and get anywhere from 1500 to 15000 btus; clearly I'm not doing it right!

 - Ed.