New house questions


  #1  
Old 12-05-05, 09:51 PM
apschorr
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New house questions

My house is being built so I have a few questions.

The heat/ac contractor is using wall space for cold air returns. I told him I wouldn't mind paying for ducting but he told me this method is efficient if done right. He spanned the wall studs with 2x4s to box the wall for the return vents. He didn't cut the lumber square and there are large gaps in his framework. He didn't apply any caulk to seal the framing nor did he do anything else to seal the space. I would rather just do it right myself than argue with him or my builder because I don't see it being a lot of work. The walls have not been sheetrocked yet so I am looking for advice on what to do with the returns.

Also, there is a vertical run of oval ducting from my basement to my attic. I was told that it is the fresh air intake for my furnace. Is this normal or should the ducting continue to the exterior of the house.

I am not trying to be a harsh critic of their work but the cost of even a modest house these days justifies getting a job done right.
 

Last edited by apschorr; 12-05-05 at 10:12 PM.
  #2  
Old 12-06-05, 05:04 AM
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Using the wall cavity is typical building practice and if done properly it is ok. Although, I would prefer to use ducting as it makes it easier to clean.

The fresh air intake should be taking air from outside. I'm confused though why the duct runs from the basement all the way through and into the attic. It should just go directly out between the ceiling joists.
 
  #3  
Old 12-06-05, 05:49 AM
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Wall cavity is the norm for returns.. It does not have to be perfect.. the sheetrock will close off and seal the area.

I am not sure what you mean where caulking is needed.. Can you take pictures?

I agree about the fresh air.. I have not heard of it being done that way up to the attic.. Just out the side of the home near the furnace area.

Is that pipe wrapped in insulation from the attic down into the wall? Othewise youwill have frost on it in the winter.
 
  #4  
Old 12-06-05, 08:09 AM
apschorr
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As far as the sealing of return air wall space the big concern people express in articles they write on the internet is preventing attic air from entering and assuring air is sucked into the vent from living space and not surrounding wall space. The articles say to seal the joints where the wall studs meet the top/bottom plates and apply foam tape around the studs and top plates to seal between the studs and sheetrock. My heating contractor told me that if my house was designed to be airtight then the return air rate would be important to keep the house balanced and sealed ducting would be used, but since my house is designed to breath the return air doesn't have to be airtight. I don't know much about all this but a lot of articles warn that using wall space for return air is not effecient and creates a pressure imbalance. Some even show little cartoons with the walls of the house being bowed in or out because of the pressure differential. Now I seriously doubt the furnace is going to implode my house because it can suck air like a jet engine but I am just trying to learn if sealing the wall space and joist panning is something I should do.

For the furnace air intake, I should have asked it differently. They are installing a high efficiency Gibson and there are two large (approx 4") pvc pipes running horizontally from the furnace to the outside of the house. There is also an oval metal duct, approx 3" x 12" that runs vertically from my basement to the attic. I was try to figure out what this duct was.
 
  #5  
Old 12-06-05, 10:47 AM
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How is this the duct in the attic finished? Is there a grill on the end? Is it open?

How is the duct finished in the furnace room? Is it connected to something? Is it open? Can you feel a cold draft coming down from it?
 
  #6  
Old 12-20-05, 08:43 PM
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Silicone is cheap.......I always seal the studs when I frame for my air returns. Wall cavities are adequate for returns but ducts are better. Ask him if he would mind leaving some foil faced cardboard panning for you so you can line the spaces. Just cut it and staple on. Then you can silicone the joints. Are you sure the 3 x 10 duct isnt a bath exhaust? Rangehood?
 
  #7  
Old 12-20-05, 10:25 PM
apschorr
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The Pipe In Question

I remembered to ask my builder about this piping and he said it is the fresh air intake for the furnace. My house is a ranch with a basement, the top of the pipe extends vertically about 2 feet into the attic which he says is to make sure it is well above the insulation. It then runs vertically in the wall and the bottom of the pipe terminates a few inches below the main floor in between two joists that have been panned for return air. So when the furnace kicks on it will draw air from the return air vents located in the house and also from my attic. That got me thinking if the attic air is really "fresh air". Should I leave it alone or cap it and run a duct in my basement from the exterior to the current return air ducting?
 
  #8  
Old 12-21-05, 05:26 AM
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So just to clarify...
You are saying that the "fresh air" from the attic is going directly into the return air ductwork?

Some quick internet searches indicates that this may meet code in your area, however, there are indications that potential problems such as shorter equipment life, poorer performance in unusually cold temperatures and possibly voided warranties.

Go here for more details...

http://www.blueflame.org/datasheets/combustair.html
 
  #9  
Old 12-21-05, 04:42 PM
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3 x 12 thats one big fresh air intake! Id look in to High RH in the summer with that big hole bringing in moisture!
 
 

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