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-   -   Attic heat vs upstairs tempature (http://www.diychatroom.com/f103/attic-heat-vs-upstairs-tempature-148520/)

BIGGUN 06-28-2012 05:28 PM

Attic heat vs upstairs tempature
 
Hello from south Louisiana.

I'm really bad about explaining,so please bare with me.

This is the time of year when my upstairs AC struggles and my electric bill almost doubles.I have a fairly new two story sunrise home built in 08 that is 3200sq living.Its brick on the front and side,but vinyl siding on the back that is facing wes:furious:t.My downstairs ac unit is a 3.5 ton and upstairs 2.5 ton both goodman brand.Within the last three years of owning the house I've put up eclipse blinds on all the windows and added 6 new AC vents,three downstairs and three upstairs.One of the added upstairs vents is blowing down the stairs and the other blowing down to the door from the second story ceiling(its open there)

This week has been in the upper 90's and lower 100's(typical) and my upstairs AC is only cooling the upstairs to 80 degrees.Downstairs is fine as usual.I do have vents in the sofet and a ridge vent that's designed to keep the attic cool,but when i put a thermometer it maxed out at 120+.I have insulation that is code and that's all that's been done bye the builder.

This last monday i went to walmart and bought a big(about 3' round) industrial fan and put it in front a octagon vent that on the exterior wall(i forgot to mention) close to the roof.The idea is to blow some of the heat out of the attic to try to cool it off.To my surprise it helped and lowered the temp to 115 and allowed the upstairs to maintain at 80 degrees(was 84)

My question is there a tempature that the attic needs to stay at and with me blowing the heat out the side(bottom of the attic)helping even thou i have a ridge vent?Should i be pushing the heat upwords toward the ridge vent?

Windows on Wash 06-29-2012 08:25 AM

Convection (provided you have adequate and balanced venting) provides all the venting that you need via soffits and ridge vent.

Your issues with heat (assuming the venting is proper) are insulation and envelope related.

Look up one of the several threads on air sealing and insulation.

Theoretically, attic temperatures are of no concern (assuming its vented right again) and your issues are along the attic floor, insulation layer, and air barrier layers.

joecaption 06-29-2012 10:47 AM

Insulation done to code to me means mimium code.

http://www.energystar.gov/index.cfm?...sulation_table

Since that house was built I'd bet the min. amount has changed and been increased.

There can never be to much insulation in an attic, I'd also bet no one did any air sealing around the ceiling fixtures and holes where wiring was run before the insulation went in.

ionized 06-29-2012 04:33 PM

Too bad if air sealing is not good on such a new house. Is your air handler in the attic? What parish are you in? You might consider hiring an energy rater to evaluate your house. They can identify the low-hanging fruit for energy improvements. They can also identify government and utility subsidies for your area.

Check Resnet for an energy rater.

BIGGUN 06-29-2012 07:38 PM

Quote:

Originally Posted by Windows on Wash (Post 953883)
Convection (provided you have adequate and balanced venting) provides all the venting that you need via soffits and ridge vent.

Your issues with heat (assuming the venting is proper) are insulation and envelope related.

Look up one of the several threads on air sealing and insulation.

Theoretically, attic temperatures are of no concern (assuming its vented right again) and your issues are along the attic floor, insulation layer, and air barrier layers.

Thanks for the advice.I can feel cool air seeping threw the vents and fixtures.I'll do a search on that too.


Quote:

Originally Posted by joecaption (Post 953952)
Insulation done to code to me means mimium code.

http://www.energystar.gov/index.cfm?...sulation_table

Since that house was built I'd bet the min. amount has changed and been increased.

There can never be to much insulation in an attic, I'd also bet no one did any air sealing around the ceiling fixtures and holes where wiring was run before the insulation went in.

I bet your right.I had a inuslation guy come out and he never called me back with a quote.I will do some homework on the insulation.


Quote:

Originally Posted by ionized (Post 954132)
Too bad if air sealing is not good on such a new house. Is your air handler in the attic? What parish are you in? You might consider hiring an energy rater to evaluate your house. They can identify the low-hanging fruit for energy improvements. They can also identify government and utility subsidies for your area.

Check Resnet for an energy rater.

Its right under the attic entrance.I'm in prairieville,la which is ascension parish.I'll look into the energy rater too.

Gary in WA 06-30-2012 01:45 AM

Some late-night reading for you: http://www.buildingscience.com/docum...o-in-the-south

http://www.buildingscience.com/docum...humid-climates

Gary

gregzoll 06-30-2012 02:16 PM

That size of home, I would have two units. One for upstairs, one for downstairs. Heat gain can cause problems also. Windows even though they have drapes pulled across, will still allow the room to heat up. Maybe look at placing UV Film on the windows, to cut down on heat gain, and also get the temps of output and intake air to the unit from various places in the home and post back what they are.

What is your temp in the attic space during the peak of the day? If there are any air leakage into the home from the attic, it can also cause the hvac to pull it into those rooms that it is trying to cool.

Comforthome 06-30-2012 08:59 PM

Another item to check, your access to the attic. Is it a pull down stair or hatch? If they are not air sealed and insulated you have one very big hole in your attic. Where is the access located? If it's in the hallway by the stairs, it could be drawing the warm air in. New minimum codes now address air seal and insulating the access.


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