attic ventilatoion

[rittz]

Do "whirly birds" .... the roof mounted attic vents that we see on many roofs actually provide proper ventilation. I have even seen some that were running backwards. How much CFM would be appropriate for a mechanical attic fan heat/humidity controlled for a house sttic say 1500 sg ft

 

[AbbyNormal]

In the cooling mode, powered attic vents can be a disaster,especially if you live somewhere humid

They can end up depressuring the living space below and cause a lot of infiltration

You want to vent attics to stop/reduce icycles and ice dams

Take the "V" out of HVAC and you are left with a HAC(k) job.

 

[TXiceman]

In addition to the "turbines" you will need adequate eve vents to allow air to move through the attic. You want to rid the attic of heat and humidity.

The approach to attic ventilation varies abit with regard to your location. Do you have cold winters or hot summers to deal with?

Ken

Ken
KE5DFR

 

[rittz]

we have both ..... hot summers and cold winters. To me we need ventilation in winter to pevent condensation in the attic .... in summer we need nentilation to reduce the attic temperature an d save on ac

 

[imok2]

Natural ventilation "turbines" is the most common and energy-efficient method of achieving attic temperature and moisture control. This method takes advantage of two principles. First, as air is heated it becomes less dense and rises. Second, wind movement over and around a home creates areas of high and low pressure. If a space has high air outlets in conjunction with low inlets, ventilation occurs as the air within the space is heated. The greater the vertical distance between the outlet and inlet, the greater the ventilation rate will be. Thus, roof outlets should be at or very near the ridge, and inlets should be under the roof overhang or near the ceiling line.

 

[AbbyNormal]

The flush out the heat mindset is only beneficial in a non insualted attic

some info on when you need attic vents

http://www.buildingenvelopeforum.com/ice1.htm-

Take the "V" out of HVAC and you are left with a HAC(k) job.

 

[AbbyNormal]

scroll well down on this page they discuss the ice dam article

http://www.buildingenvelopeforum.com/letter.htm

Take the "V" out of HVAC and you are left with a HAC(k) job.