HVAC in attic

[ron]

[TURTLE]

This is Turtle.

this is the hottest time of the year and you need to check the temperature up there at about 3:00 P.M. . Any temperature of 120ºF or more up there is hurting in the form of heat being transmitted into yoiur duct work to be brought into your house.

First Ridge venting in my opinion is trash because i have seen attic i would have to go into with temp.s of 140ºF and have ridge roof vent system on them. Now also here it is nothing to see 100ºF+ all the time and hot sun on the roofs.

Second Even with a Ridge vent. You can add a motorized attic vent and if the ridge vent holds the temperature down . The Motorized vent will never come on because of it being run by a thermostat to come on at set temperatures.

TURTLE

[ron]

TURTLE wrote:

This is Ron,

The real issue at hand is heat oppression and I agree with Turtle, Ridgevents are for the most part a waste of time. But i would go a step further and offer that electric fans as their presently offered are are an even bigger waste of money and energy. The issue is understanding the dynamics of heat. At dawn the roof gets hot, the air in the attic begins to warm, expand and then rise. Conventional thinking is that as hot air rises, it will draft through either passive ventilation or ridgevents, and replacement air will be replaced through your soffit ventilation. The bonus with a "ridgevent" is that any breeze might create venturi, and can be that much more efficient. It simply doesn't work, Heat pressurizes the attic and your soffit vents prove it every afternoon. Hold up a feather duster to your soffit and you'll see heated air streaming from them. That pressure literally impregnates everything in your attic, including the ceiling itself. Heat gain compounds, once it's allowed to begin it cannot be stopped short of dusk. 110 volt fans are thermostatically controlled, they start out behind and never can catch up. In addition over 80% of all fires in attics are attributable to electric fans shorting out. I seriously recommend solar powered attic ventilation. It's proactive, It's on at dawn, before the heat of the day. A properly sized unit (1100 CFM+) can actually keep heat gain from happening all day long.

[RP]

If you have air exhausting from the soffit vents then you either have ductwork problems (leakage into the attic) or attic air exhaust problems. This isn't normal. You could have a light breeze hitting the opposite some other side of the house or a lateral breeze across the side you're on causing a venturi effect. Normally there is a net rise of air through the soffit. Heat doesn't generate extra air molecules. If there is air leaving the roof vents then it had to enter somewhere first. If its exiting everywhere through every opening then you should probably call ghost busters or get the ductwork repaired.

hvacrmedic

[Jack]

Lots of post recently about attic venting. One of my HVAC units is in the attic. Would an attic fan help with the HVAC? It gets pretty hot up there, even with a ridge vent and undereave venting. Thanks.

[nicksanspam]

Two 8 ft^2 gable vents 8' above soffit vents can move 1100 cfm from an attic that's (1100/16.6/16ft^2)^2/8' = 2.1 F warmer than the outdoors...

Nick

[Roy Starrin]

Any preferences as to makes, mods, etc (other than 1100CFM+), or,conversely, brands to avoid. And, how about this aspect of the problem in general:

[TURTLE]

or

This is Turtle.

Roy the fellow was speaking about the Electric blower fan type attic fans and in all cases said the problem was not installed correctly in every cases he made again them. Everything he said bad about them , was the cause of not enough of supply air to the fans in every cases he sighted and if they were installed correctly he would not have a case at all as to say they were bad. Now he does like Solar type and I can't say bad about them.

TURTLE