# Making ductwork and a finished basement coexist



## Badfish740 (Oct 29, 2006)

I have a two bedroom ranch which is about 25 feet wide and nearly 45 feet long. The oil furnace and A/C unit sit at one end of the house and the main HVAC delivery duct runs parallel to the main support girder, which is the centerline of the house. The duct runs the entire length of the house. In addition to the air delivery duct there is also a return that also runs nearly the length of the house. There is one main return located in the center hallway of the house, but each room has it's own return as well. They seem to be paired with the delivery vents (2 delivery/2 return in the living room, 1 delivery/1 return in each bedroom, etc...) which I've never seen before, but this is also my first house. 

The issue is that these two ducts interfere with the headroom in the basement. From the slab to the joists is about 7' 4". The main duct is about 14" which results in a clearance of barely 6' 3". Add in about 1" for berber carpet and padding plus the framing/sheetrock necessary to box the ductwork in and there would be no way that a person of even average height would be able to walk beneath it without stooping. 

While I do want to somehow move this ductwork, I'm also concerned about the prospect of negatively affecting the airflow in my house. Is there any way to move the ductwork so that it runs along the outer wall rather than through the center without restricting airflow? Would I be able to switch to a wider and narrower duct in order to increase headroom?


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## yuri (Nov 29, 2008)

You can use a wider and narrower duct. The whole project is going to be very expensive and rarely done.


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## Badfish740 (Oct 29, 2006)

yuri said:


> You can use a wider and narrower duct. The whole project is going to be very expensive and rarely done.


So in other words the basement simply isn't finishable-that's what I was afraid of.


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## yuri (Nov 29, 2008)

Instead of boxing in the ductwork try painting it or coating it with spray stipple? or something cosmetic. Instead of thick carpet try the various thin hardwood DIY flooring. All these may save you headroom. I am 5ft10 so not everyone will have a headbanging experience. Basements were never really designed for living space. More for the washing machine, root cellar type uses. Be creative and duck occasionally.

Good Luck


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## butlersprints (Nov 28, 2008)

Badfish740 said:


> So in other words the basement simply isn't finishable-that's what I was afraid of.


the most expensive part is to have transition piece made from plenum to first duct section. You can buy duct work at big box stores, & diy. You will gain approx. 6", so you decide if thats worth the cost to change.:thumbsup:


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## butlersprints (Nov 28, 2008)

Another choice is to be creative, I have seen a basement ceiling done with lattice that was stained and hung with wire, making it removeable if needed and gave the room character as well. And lattice is only 1/2" thick. Just a thought.:whistling2:


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## Aggie67 (Dec 20, 2008)

If I really wanted it bad enough, I'd have the duct made up and just replace it with wider, shallower duct. Duct isn't that expensive. Don't go to a big box for it, though. Find a sheet metal shop and have it made. Very inexpensive. For a 45 foot run both ways, they could make that up in a day or so. I've called many orders in where they have it ready for pickup the next afternoon.

The connections will be the issue. Tell me the diameter or HxW of the supply/return branches coming off the main duct, and take pictures of each joint, showing the type of joint. 

I'll have my SMACNA manuals and software in front of me tomorrow, but this does qualify as something we can solve here on this board (please note that as a pro I usually charge for this info). I'll walk you through how to size it, sketch it, order it, what style of connectors, etc. The furnace transitions will be the toughest part, but it's not brain surgery. Post me the pics so I know you're serious, and we'll get started.


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## beenthere (Oct 11, 2008)

I don't know if Ive seen 14" high duct in a basement before.
On a house that small.


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## David I (Aug 30, 2009)

*Duct work*



Aggie67 said:


> If I really wanted it bad enough, I'd have the duct made up and just replace it with wider, shallower duct. Duct isn't that expensive. Don't go to a big box for it, though. Find a sheet metal shop and have it made. Very inexpensive. For a 45 foot run both ways, they could make that up in a day or so. I've called many orders in where they have it ready for pickup the next afternoon.
> 
> The connections will be the issue. Tell me the diameter or HxW of the supply/return branches coming off the main duct, and take pictures of each joint, showing the type of joint.
> 
> I'll have my SMACNA manuals and software in front of me tomorrow, but this does qualify as something we can solve here on this board (please note that as a pro I usually charge for this info). I'll walk you through how to size it, sketch it, order it, what style of connectors, etc. The furnace transitions will be the toughest part, but it's not brain surgery. Post me the pics so I know you're serious, and we'll get started.


I would like to ask your advice with similar replacement duct scenario and respect it is a professional service. Look forward to chat


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## Slick Will (Dec 22, 2010)

*you can do it, if that is what you want*

I agree with what I've read so far - it can be done. I would advise that you consider to not only moving the duct work to an parimeter wall but also seek insight on running a split return. I ran two returns in opposite directions to increase available headroom & capcity. If you simply use a smaller return duct I would advise a booster fan to increase flow back to the furnance. as with anything to do with pipes or ducts the joints and connectors are where the cost add up, so ask around. As a D-Y-Ier ask about which parts of the job you can tackle to get a discount and which parts you actually need the pros on. 

I have 14 yrs experience in commercial boilers in Mi and have rarely found duckwork jobs the average person could not do with a little research and common sense.

My last bit of advise is to tape, wrap, and insulate all of the duct lines you can to protect against leaks to improve effeciency... I read somewhere that you could be wasting as much as 30-40% of your conditioned air if this is not done!!!! that could be enough ina short period of time to pay for the change.

good luck!!!!


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