Proper insulation for the Chicagoland area?

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We recently purchased an brand new home in August and this is our first year in the house. The house is much larger then my previous house (3200 sqft vs 2400 sqft) and I've noticed that the furnace runs much longer and much more often then my previous house. Based on the specs of the builder, they put in R-11 batts in the ceiling with R-27 blow in "for tight insulation" and R-13 batts in the walls.
Does this sound sufficient? I'm not sure what the total R value would be for the ceiling (do you add the R-11 and R-27 to come up with R-38)?
This past weekend, it was approx 0 degrees out. I turned the furnace down to 62 before we left for a day trip. When I returned, I set the furnace back to 68 (where I normally keep it) and it took approx 2.5 hours for the house to heat from 62 to 68. This seems very excessive to me.
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On Wed, 2 Jan 2008 11:10:17 -0800 (PST), ATJaguarX

And to me: I live in a climate similar to yours, and my 2-stage gas furnace takes less than an hour to bring the house up from 60F to 65F, closer to 35 minutes.
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I've read the following online: "A properly-sized system is designed as closely as possible to the needs of the house; on the coldest days of the year, it should run almost continuously."
http://www.hometips.com/cs-protected/guides/furnaces/furnace_size.html
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Bull. I live north of Chicago and it takes about 1/2 hour to get the house from 62 to 67. In fact it does it every day. My furnace goes off at 8am and doesn't turn on till 3pm every day. The lowest the temp gets is 60 deg and thats when it's 10 below outside. It sounds like your system is too small for the house. It wouldn't hurt to contact the building department with these questions. Lou
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Another thing is that no matter what the wrapper says, the quality of the insulation depends a lot on the quality of the installation. Also, if you have crappy air sealing, that isn't going to help either. I think that unless you live in a place that is 70 degrees year round, you should have r 21 in your walls, but that's just my opinion.
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well new high efficeny furnaces are sized closely to the home, for most efficent operation. but gone are the days you could raise the temp of the home from 50 to 70 in a hour. new furnaces just arent that oversized.
on insulation the higher the R value the better.
ideally the builder would of used closed cell foam, its costly but its over R6 per inch.
of course you would of had to pay the added cost, and since its not a see me item like granite countertops, its harder to justify.........
minimum R standards for ew homes should be raised
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What! LOL. (that quote).
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With your huge house and perhaps cathedral ceilings, great room (high ceiling) and all the other popular things now found in new homes, you probably have lousy air circulation and a sadly undersized furnace. IMO you need to get some competent help to analyze and correct the problem. Be ready for a shock when you get the quotes for the work. Deepest sympathies.
Joe
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I have the builder and the HVAC guy coming on Friday to see what's going on. You mention "competent" help to analyze and correct the problem. Who would I turn for this? Should I not trust the opinion of the HVAC guy and the builder?
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Come on now, these are not the guys that caused the problem. Are you going to let them brain wash you into believing that the situation is normal? Whoever designed the house is the cause of the poor performance. Get a decent architect on board, someone familiar with ALL aspects of residential design. If you are near a major university with such a department, ask if someone there can recommend a firm in your area. Browse the Yellow Pages. Knowledge is power. Good luck.
Joe
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I am just north of you, in WI, and R38 (which you have) is code for ceilings, and I think R13 is still ok for the walls. Hard to expect a builder to go beyond the minimum standard.
I'm not too surprised that, with the extreme temps, it took a long time for the furnace to get up to temperature. The furnace should be sized to keep up with the heat loss on the coldest days.
JK
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It may all be normal, proper sizing of a furnace is that it runs nearly continously at the coldest day which is about -20f in chgo. 2.5 hrs is not much seeing all the furniture and walls you must heat that are now cold. Oversizing a furnace leads to short cycling and uncomfortable heat. is it a 2 stage unit, you might check that the second stage works. You have R38 , or at least you think you did, as nobody cheats, and blown in settles more than batt, Measure it yourself and calculate R value. But what you have is code, its the minimum, not optimal, and the code is old based upon cheap gas so do your own research. Optimal some say R 60 some say more. Im sure a laod calculation was done and you should have looked into projected heating costs, and they might be normal, depending on your design.
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well you could add a extra furnace for use only in extreme situations........
but the most efficent furnace is one that runs continiously on the coldest days
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I posted a comment like yours above ("but the most efficent furnace is one that runs continiously on the coldest days") and others laughed about that.
My buddy is a construction super intendent for a big builder in the area and they sell houses that are similiar and size and he said that they usually have 2 furnaces in a house like mine. There is no doubt that I would love to have a seperate furnace for the 2nd floor.
Another question... this same buddy says that they do one single duct run to the attic and then branch it off from there to the individual rooms with the registers on the ceilings (2nd floor). Mine has individual duct runs with individual dampers in the basement for each room on the 2nd floor. Which setup is better? I would assume individual runs would be better since its not going to a cold attic, but he thought my setup was strange. Adding a 2nd furnace will be more of a headache with my setup (I would assume).
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being a construction superindent means he is hopefully a expert at building stuff. he follows plans.
he doesnt design building and probably isnt a HVAC expert either.
Thoise 90%+ efficent furnaces are rated like that during continious operation. thats the coldest day of the year.
on a 50 degree day in a area that typically sees zero degrees the 90+ furnace isnt near its top efficency.
the basement feed furnace ducts are more efficent than top feed.
with top feed the hot air must be pushed up all the way to the attic, and back down again to floor level.
with basement feed hot air is still pushed, but natural convention hot air rises cold air falls helps a lot. more efficent less electric blower power needed, less ductwork needed.
down feed is used for open floor plans and appearance but its less efficent
the reason constant operation is more efficent? the furnace transmits all the heat it produces into the air. in a cycling situation much heat never gets moved to where you need it, on first heating things up before blower turns on, and afterward, when hotr heat exchanger is left to cool.
have you noiticed high efficency furnaces tend to blow cooler air on start up? thats a attempt to minimize heat lost during start up...
note the dual speed furnaces are another attempt to address these losses.
the idea is in less than full heat needs run the furnace at less than full btus continiously, this minimizes losses
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In article <62a14e8c-e9fe-4599-a1fb-a4dc2b105bd9

In a cold area like yours, you should have thermal break insulation in the walls, and at least R-19. R-38 in the attic is absolute minimum. Your furnace should respond quicker if it's only 0 degrees. It will probably be inadequate during really cold weather, which will sometimes reach -40.
You might think about paying for an energy audit. It's pretty common for plumbers and electricians to rip up insulation and not replace it. You may have some gaping holes in your envelope. If you discover any, see if the home builder is a member of his association's home warranty program. You may be able to get it fixed with minimal cost to you.
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wrote:

I tried contacting my local gas company and they do not provide any type of energy audit (the CS rep didn't even know what I was talking about). How can you find these "gaping holes" in the envelope?
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It is true that for best efficiency, the furnace should be sized so that it is just able to keep up on the coldest days. An oversized furnace that cycles frequently will waste energy. Let people laugh if they want, they can laugh all the way to the bank (to get more money out to pay their gas bill). That being said, as you have noticed, a smaller furnace can take a long time to heat the house up; 2.5 hours seems like too long to wait for a standard thermostat set-back. The poster that asked about whether the second stage is working might be on to something; something for the HVAC guy to check out. Have the house nice and cold when he shows up. If you just want/need a bigger furnace you might be able to cut a deal with the builder on that.
Chicago has weather records going back well over 100 years and the coldest it has ever been was -27 Fahrenheit. So if the system is good down to -20 or so that should suffice.
Your insulation is the modern standard practice. Arguably there should be more but at this point it is hard to add it anywhere but the attic, where you could just have more blown in. There are lots of old houses in Chicagoland with NO insulation in the walls - at least you're better off than they are!
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Heathcliff wrote: ...

How, precisely, do you come to that conclusion? Given two otherwise comparative units, how does size alone affect efficiency?
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Fair enough, here are some references:
http://www.cmhc-schl.gc.ca/publications/en/rh-pr/tech/03-109-e.html (canada mortgage and housing corporation technical bulletin)
http://www.alpinehomeair.com/Furnace-choosingsize.cfm (home heating supply co.)
and it's not just efficiency, but also early failure of the unit is a possibility. -- H
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