insulating basement ducts.

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  #1  
Old 07-23-10, 09:12 AM
J
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insulating basement ducts.

My unfinished basement seems to be atleast 10 degrees cooler than the first and second floors. all the ducting is exposed and isn't insulated. What would be the best/cheapest way to insulate?

I'm thinking of using this for the 6" round pipes,
http://www.lowes.com/pd_77405-59558-BPC625R6_0_?productId=3143507&Ntt=duct&Ntk=i_products&pl=1&currentURL=/pl__0__s?rpp=30$Ntt=duct$identifier=

the main problem seems to be with the square ducting. both the feed and return square ducting are next to eachother and are about 40' long with the a/c / furnace in the middle.

Could I just use insulated sheathing to cover both pipes together then tape all the seams?
Shop Dow 1/2" x 8' x 4' R-3.3 Polyisocyanurate Rigid Foam Insulated Sheathing at Lowes.com

past one side of the square ducting there's about 15' of large circular 12"? ducting in the crawlspace with some 6" that goes across.

Could I just use some radiant barrier film to cover that?
Amazon.com: Reflectix #RB 48125 48x125' Radiant Barrier: Home Improvement
 
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Old 07-23-10, 09:16 AM
C
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Are you doing this for heating or A/c ? Where are you located ?
 
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Old 07-23-10, 09:26 AM
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both, they're connected together in a central system. I live in central, OH. Outside temp is anywhere from 100deg (today) to 0deg.

Forgive my ignorance, this is my first house that we're buying from my father and am looking to save as much on utilities as possible.
 
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Old 07-23-10, 09:49 AM
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Its completely normal for a basement to be considerabily cooler than the upper floors. That's not due to your uninsulated HVAC ducting, but due to the basement being below grade. Generally, HVAC ducting is not insulated in unfinished basements, as it is not cost effective. Since heat rises, any heat losses from the ductwork in the winter will rise into the living area. In the summer, there won't be much cold loss from the ductwork, due to the cooler basement temperatures. Your basement stays at a fairly constant temperature summer and winter, and any savings due to adding insulation to the ductwork will be very minimal.

You'd get much more bang for your buck adding additional insulation to your attic or making sure your windows are well caulked and weatherstripping on doors is on good condition.
 
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Old 07-23-10, 10:14 AM
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I understand. Currently I believe the a/c's been on 24/7 and its freezing (50degs) in the basement but the 1st floor sits at around 70. I didn't know if spending $100-300 insulating everything would be cost effective.
 
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Old 07-23-10, 02:05 PM
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Insulating your ducts is one thing, but you should check to see if you have any significant air leaks in the supply ductwork. Most basements run around 65 degrees in the summer time. You should check your ductwork while the AC is running to see if there are massive leaks that are diverting the air from the upstairs into the basement. Usually duct joints are sealed with the silver duct tape.

70 degrees is pretty cool for AC in the summertime. I'm not surprised your AC is running 24/7 in this heat if your thermostat is set that low.
 
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Old 07-23-10, 02:15 PM
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I agree - probably worth the cost of a roll of foil tape to seal leaks in the ductwork but I wouldn't bother with insulation

Most of the time cold basements and hot upper floors is best addressed by better diversion of the conditioned air to the upper floors
 
 

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