EcoRenovator  

Go Back   EcoRenovator > Improvements > Solar Power
Advanced Search
 


Blog Register 60+ Home Energy Saving Tips Recent Posts Search Today's Posts Mark Forums Read


Reply
 
Thread Tools Display Modes
Old 07-19-12, 06:49 PM   #21
MarkM66
Helper EcoRenovator
 
Join Date: Jan 2012
Location: st.louis
Posts: 33
Thanks: 0
Thanked 1 Time in 1 Post
Default

Quote:
Originally Posted by Xringer View Post
Wow, it's been cooking there since May 1st. Very Texas like...

Yeah, I would consider a ventilated attic and maybe a reflective barrier to bounce back the radiated heat from the roof..

Weather Station History | Weather Underground
Yeah, it's been a super hot summer, and no relief in sight.

I think I might try one of those gable fans. Thanks.

MarkM66 is offline   Reply With Quote
Old 07-19-12, 06:50 PM   #22
Xringer
Lex Parsimoniae
 
Xringer's Avatar
 
Join Date: Feb 2009
Location: Woburn, MA
Posts: 4,873
Thanks: 106
Thanked 245 Times in 225 Posts
Default

Gary said,
There are a bunch of refs out there saying that AC powered attic vents don't payoff.

I think of my AC powered attic fan kinda like a very low cost heat pump.
It started up around noon today, but we never turned on the AC until about 3 PM.
By 6:30 PM it was cool enough to shut off the Sanyos again.
Without the attic fan, the house heats up earlier and stays hotter longer.

When we did turn the Sanyos on this afternoon, the house cooled down a couple of degrees, very quickly..

Right now, 7:45 PM, the ceilings are at 76.6F and the attic sensor is at 93.1F.

It's 76 indoors and 71.6 outdoors (and dropping fast)..



In my case, I don't mind paying a few extra bucks for power,
when it allows us to enjoy more hours of mild summer weather.
Not really expecting the fan to pay for itself in 10 years..
__________________
My hobby is installing & trying to repair mini-splits
EPA 608 Type 1 Technician Certification ~ 5 lbs or less..
Xringer is offline   Reply With Quote
Old 07-19-12, 06:53 PM   #23
Xringer
Lex Parsimoniae
 
Xringer's Avatar
 
Join Date: Feb 2009
Location: Woburn, MA
Posts: 4,873
Thanks: 106
Thanked 245 Times in 225 Posts
Default

Quote:
Originally Posted by MarkM66 View Post
Yeah, it's been a super hot summer, and no relief in sight.

I think I might try one of those gable fans. Thanks.

It's going to be too hot to work up there..
Get some work lights and wait until about 1AM to go up there..
Or, take some big fans up there to keep a little cool when installing it..
__________________
My hobby is installing & trying to repair mini-splits
EPA 608 Type 1 Technician Certification ~ 5 lbs or less..
Xringer is offline   Reply With Quote
Old 07-19-12, 07:49 PM   #24
GaryGary
Apprentice EcoRenovator
 
Join Date: Nov 2008
Location: SW Montana
Posts: 139
Thanks: 1
Thanked 21 Times in 15 Posts
Default

Quote:
Originally Posted by Xringer View Post
Gary said,
There are a bunch of refs out there saying that AC powered attic vents don't payoff.

I think of my AC powered attic fan kinda like a very low cost heat pump.
It started up around noon today, but we never turned on the AC until about 3 PM.
By 6:30 PM it was cool enough to shut off the Sanyos again.
Without the attic fan, the house heats up earlier and stays hotter longer.

When we did turn the Sanyos on this afternoon, the house cooled down a couple of degrees, very quickly..

Right now, 7:45 PM, the ceilings are at 76.6F and the attic sensor is at 93.1F.

It's 76 indoors and 71.6 outdoors (and dropping fast)..



In my case, I don't mind paying a few extra bucks for power,
when it allows us to enjoy more hours of mild summer weather.
Not really expecting the fan to pay for itself in 10 years..
Hi X,
Sounds like the way you manage the time that its on makes it work well for you.

I think there are a lot of variables -- how well the living space ceiling is sealed against airflow up into the attic, whether there is also a radiant barrier, how much power the fan uses, whether its a not so expensive DIY install or a more expensive install, ... I should not have made a blanket statement.

I got one of the solar powered attic vent fans when they were closing them out at Costco for $80. Its now installed near the outlet of my solar air heating collector in the shop to keep the hot air from stagnating up at the ceiling in the winter. It does a really nice job of keeping the air mixed up -- no controls needed it just runs automatically when its sunny

Gary
GaryGary is offline   Reply With Quote
Old 07-20-12, 02:18 PM   #25
Etced
Lurking Renovator
 
Join Date: May 2012
Location: Tennessee
Posts: 2
Thanks: 0
Thanked 0 Times in 0 Posts
Default Whirlybirds

These Whirlybird type vents work fantastic and they take no power. My ac would lose ground when it was 95 plus outside. This year I installed 4 of these on my roof. The ac not only keeps the temp now, but actually cycles on and off rather than running continuously late in the afternoon.
Attached Thumbnails
Click image for larger version

Name:	vent.jpg
Views:	815
Size:	16.0 KB
ID:	2421  
Etced is offline   Reply With Quote
Old 07-20-12, 03:20 PM   #26
Xringer
Lex Parsimoniae
 
Xringer's Avatar
 
Join Date: Feb 2009
Location: Woburn, MA
Posts: 4,873
Thanks: 106
Thanked 245 Times in 225 Posts
Default

I've seen a few of those around and wondered how they spin, is it wind or the hot air updraft?

Some people don't like them..
Attic Ventillation. Roof vents vs Whirly birds.
__________________
My hobby is installing & trying to repair mini-splits
EPA 608 Type 1 Technician Certification ~ 5 lbs or less..
Xringer is offline   Reply With Quote
Old 07-20-12, 03:25 PM   #27
Etced
Lurking Renovator
 
Join Date: May 2012
Location: Tennessee
Posts: 2
Thanks: 0
Thanked 0 Times in 0 Posts
Default

Actually both ways work , it's amazing how many cfm's they can pump out even with no wind.
Etced is offline   Reply With Quote
Old 07-20-12, 04:15 PM   #28
Xringer
Lex Parsimoniae
 
Xringer's Avatar
 
Join Date: Feb 2009
Location: Woburn, MA
Posts: 4,873
Thanks: 106
Thanked 245 Times in 225 Posts
Default

If the wind turns them and the wind pressure on one side doesn't interfere
with drafting air up and out, that's cool..
But, around here there isn't a lot of wind on many of the hotter days..
Average wind speed here over the last 7 days is 0.5 mph
WOBURN WEATHER CENTER - Weekly Conditions
During the day, it's about 2 MPH sometimes.. In the winter, we get a lot more wind..
And that's when I don't mind some hot air in the attic.

However, if it's turning when the wind isn't blowing..?. That means the hot air
that's drafting up out of the attic is doing work.
Which means the air flow is being restricted, slowed down.

IMHO, a long ridge vent on the apex has got to be the best way to vent.
But it needs some air input in the soffit area to work best.

Sadly, my house didn't get any over-hang/soffit area.

My ridge vent spacer material is a plastic mesh cloth (like a pot scrubber).
I'm pretty sure it's the worse type to use, if you want good air flow.

The roofers has installed a real nice open-air-flow vent,

but they didn't have the proper size cap shingles to cover it.. Had to replace it with mesh junk..
__________________
My hobby is installing & trying to repair mini-splits
EPA 608 Type 1 Technician Certification ~ 5 lbs or less..
Xringer is offline   Reply With Quote
Old 08-12-12, 01:10 PM   #29
DocAir
Guest
 
Posts: n/a
Default

Don’t Waste Money on Powered Attic Fans
Barry Westbrook, P.E.

Most of us were taught from an early age that we can reduce our summer time cooling costs and extend the life of our asphalt shingles by sucking the hot air out of the attic. This is a wasteful, damaging, and dangerous myth that needs to be debunked.
Ironically, powered attic fans will almost always increase the cost of cooling the home. In many cases, they will also elevate radon gas levels in the living spaces of the home and create moisture management problems during hot weather. Finally, powered attic fans will not extend the life of the shingles. Why is this true?
Building scientists at Oak Ridge research facilities have conclusively proven that the amount of ventilation in attics does not significantly affect the cooling requirements of the building nor does it affect the life of the asphalt shingles. These findings are in direct contradiction of the long-held beliefs about the need for attic ventilation.
It turns out that actively ventilating the attic has almost no effect on the surface temperature of the asphalt shingle. Also, most of the heat transmission from the roof is radiant energy coming directly from the roof decking to the ceiling of the home. Although the air in the attic also gets hot, the air is not heating the ceiling. The ceiling is heating the air. Ironically, in most homes, powered attic fans literally suck the conditioned air out of the living space and increase the cost of cooling.
Considering these facts, is there a need for attic ventilation at all? For most attics, the answer is yes. During the winter months, the roof surface becomes cold. Without some ventilation, moist air from the living spaces will leak into the attic and form condensation on the roof decking whenever the temperature drops below the dew point of the air. Condensation on the roof decking can promote mold growth and wood rot. However, only passive venting is needed to prevent wintertime condensation in the attic. Powered attic fans are almost always installed due to concerns about hot weather.
Some attics need no ventilation at all. Many new homes and some existing homes are retrofitted with what is termed as a "closed attic assembly". In a closed attic, spray foam insulation is installed directly to the underside of the roof decking creating an “igloo” effect. This insulation thermally isolates the roof assembly from the attic. This prevents the radiant heating of the house in the summer time and prevents moisture condensation on the roof decking in the winter.

Closed Attic Assembly with Spray Foam Insulation

In summary, although there is a need for ventilation in most attics, the installation of powered attic fans are counterproductive. Homeowners looking to reduce summertime energy costs should invest in additional insulation or install radiant barriers instead.


Questions and comments can be submitted to the following address:
Barry Westbrook
℅ DocAir
4014 Flagstone Ct
Franklin, Tn 37069
615-373-2498
  Reply With Quote
The Following User Says Thank You to For This Useful Post:
Xringer (08-12-12)
Old 08-12-12, 01:26 PM   #30
Patrick
Apprentice EcoRenovator
 
Join Date: Jul 2010
Location: East Coast of Florida, USA
Posts: 149
Thanks: 2
Thanked 5 Times in 5 Posts
Default

Quote:
Originally Posted by DocAir View Post
Don’t Waste Money on Powered Attic Fans
Barry Westbrook, P.E.

Most of us were taught from an early age that we can reduce our summer time cooling costs and extend the life of our asphalt shingles by sucking the hot air out of the attic. This is a wasteful, damaging, and dangerous myth that needs to be debunked.
Ironically, powered attic fans will almost always increase the cost of cooling the home. In many cases, they will also elevate radon gas levels in the living spaces of the home and create moisture management problems during hot weather. Finally, powered attic fans will not extend the life of the shingles. Why is this true?
Building scientists at Oak Ridge research facilities have conclusively proven that the amount of ventilation in attics does not significantly affect the cooling requirements of the building nor does it affect the life of the asphalt shingles. These findings are in direct contradiction of the long-held beliefs about the need for attic ventilation.
It turns out that actively ventilating the attic has almost no effect on the surface temperature of the asphalt shingle. Also, most of the heat transmission from the roof is radiant energy coming directly from the roof decking to the ceiling of the home. Although the air in the attic also gets hot, the air is not heating the ceiling. The ceiling is heating the air. Ironically, in most homes, powered attic fans literally suck the conditioned air out of the living space and increase the cost of cooling.
Considering these facts, is there a need for attic ventilation at all? For most attics, the answer is yes. During the winter months, the roof surface becomes cold. Without some ventilation, moist air from the living spaces will leak into the attic and form condensation on the roof decking whenever the temperature drops below the dew point of the air. Condensation on the roof decking can promote mold growth and wood rot. However, only passive venting is needed to prevent wintertime condensation in the attic. Powered attic fans are almost always installed due to concerns about hot weather.
Some attics need no ventilation at all. Many new homes and some existing homes are retrofitted with what is termed as a "closed attic assembly". In a closed attic, spray foam insulation is installed directly to the underside of the roof decking creating an “igloo” effect. This insulation thermally isolates the roof assembly from the attic. This prevents the radiant heating of the house in the summer time and prevents moisture condensation on the roof decking in the winter.

Closed Attic Assembly with Spray Foam Insulation

In summary, although there is a need for ventilation in most attics, the installation of powered attic fans are counterproductive. Homeowners looking to reduce summertime energy costs should invest in additional insulation or install radiant barriers instead.


Questions and comments can be submitted to the following address:
Barry Westbrook
℅ DocAir
4014 Flagstone Ct
Franklin, Tn 37069
615-373-2498
What if the ducts and/or air handler are located in the attic space?

Patrick is offline   Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 11:23 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.
Ad Management by RedTyger
Inactive Reminders By Icora Web Design