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moving HVAC supply

post #1 of 21
Thread Starter 
I'm looking to relocat the main supply duct that goes right through the middle of my workout room of my entire basement/theater build.

Here is what I have now...



I want to put it along the wall where the xmas lights are right now.

Here is where it comes into the room...



I don't THINK it looks like something I need to call a pro in for but I wanted to question to forum here and see what the general thought was.

I was thinking one 90 degree turn to get it to the wall and another to get it going back in the same direction as it's original orientation. Then I would need to extend the smaller circular ducts going to registers?

I have no idea how much sheet metal square or round duct costs.

Does the furnace need to be "tuned" for lack of a better term to adjust to the new length for proper flow?

Thanks!


Why do builders always put these things in the middle!?
post #2 of 21
They put them in the middle because it is the most convenient for them at the time.

Fabricating sheet metal definitely requires a unique set of tools. There are some pretty good "how-to" guides out there...I moved a number of ducts, but nothing that big.

What is your end goal for the space?

Are you going to enclose it in a soffit?
post #3 of 21
Based on personal experience, if you have the space, do 2 45 degree elbows vs. 2 90's, it will give you better airflow past the transition. Also, try to source curved elbows vs. the alternative. Check my thread for some additional info...wasn't a pleasant task for me.

Here's a link to what I'm, suggesting you use if you do it:
http://www.audubonsupply.com/browse.cfm/2,142.html
post #4 of 21
Thread Starter 
Quote:
Originally Posted by Johnsteph10 View Post

They put them in the middle because it is the most convenient for them at the time.

Fabricating sheet metal definitely requires a unique set of tools. There are some pretty good "how-to" guides out there...I moved a number of ducts, but nothing that big.

What is your end goal for the space?

Are you going to enclose it in a soffit?

hmm, I hadn't planned on actually fabricating anything myself. I guess I never looked but I was planning on just buying pre-made pieces that were the dimension and curve I wanted. Is that not the way it works? I've never shopped HVAC before. Ultimately I would soffit the duct in so it won't be seen and I'll have the headroom in that workout area for overhead presses without having to be standing in a particular area that clears the duct.
post #5 of 21
This is exactly what I did. Well worth IMO.

Here is my 2nd floor supply that ran right down the center of the planned theater.


here it is now. instead of coming straight off the furnace, it was run to the left and then run down the foundation wall. This way the supply duct will be hidden in a soffit instead of running right down the middle of the theater.
post #6 of 21
Thread Starter 
Quote:
Originally Posted by NJ Jackals View Post

This is exactly what I did. Well worth IMO.

Here is my 2nd floor supply that ran right down the center of the planned theater.

here it is now. instead of coming straight off the furnace, it was run to the left and then run down the foundation wall. This way the supply duct will be hidden in a soffit instead of running right down the middle of the theater.

did your changes affect your heating system at all? As in did you notice any performance decrease?

Did you hire that work out or DIY
post #7 of 21
I hired it out. I have three furnaces. I moved two supplies and tapped into the third with an electronic damper to feed the basement. They also made their own ducts and lined them with linacoustic for the trunks that were passing through theater soffits. They only reused about a third of the material (the one supply that is the opposite side of the basement from the theater). Took them a week with 2 guys for the first 4 days and 3 guys on the last day. The 'boss' estimated a two day job so I'm pretty sure he took a bath on the job. Another contractor's estimate was double what I paid this guy.

Luckily, we did not notice any negative changes. It actually improved my sons room slightly which is easily the coldest room in the house as it sits above the garage and is at the opposite end of the house from the second floor thermostat.
post #8 of 21
Moving the main trunk is different form turning it. Usually it needs to run perpendicular to the floor joists so you can branch off with your individual runs and run them inside the joist cavities (parallel to the joists).

Also, HVAC guys will freak out at the idea of moving the main trunk at all because they claim airflow is highly sensitive to every little pressure drop in the system. I'm not convinced this is such a big issue because you could always adjust the airflow at each register in the house to compensate. Just something to think about.
post #9 of 21
This is probably one of the easier projects to DIY.

First, go to your local big box store and stroll the HVAC supply aisle. See what they have. You should be able to get the rectangular ducts that come in two "L"-shaped pieces. You assemble the two pieces into a rectangle.

You'll want to buy a few tools....heavy gloves and a set of tin snips. You should be able to find a set of three for right, left and straight cuts. They don't need to be really expensive, this is probably a one shot deal. Silver duct tape, NOT DUCT TAPE Brand. Surprisingly, Duct Tape brand CANNOT be used on ducts. And you'll want some way to hang the new ducts. Look at how your existing ducts are hung and do the same thing. (At my house, they just cut thin strips of sheet metal and bent them to make hangers.) You can extend the round the ducts with flex ducts. THey come in a box usually 25 feet long.

Then it's pretty much like putting the pireces of a puzzle together. If you can't find the 45 degree bends at your local bog box (or any other parts for that matter), try an HVAC supply house. Fit the pieces and seal with the tape.

And don't be surprised if you need to make trips to two stores to get everything you need. My biggest pet peeve during my looooong build is that I can't go to one big box and get EVERYTHING I need, especially for the HVAC and plumbing projects.

Since this is your first project like this, I would build everything along the new wall towards the connections and then do the actual connections last. It seems to always take longer than you think. You don't want to disconnect the a main trunk, be without heat and then run into a problem and have your main trunk disconnected.

One more thing since you are going to the effort of moving the main trunk. Maybe you want to think about doing this AFTER the ceiling is drywalled. That will help a lot with sound proofing. You want to completely contain the trunk inside the soffit.

Good luck!
post #10 of 21
As suggested, use the radius corners and not abrupt 90 degree corners to maintain air flow. This may be a DIY project but not necessaraly a do-it-by-yourself project. An extra set of hands is invaluable when trying to hang this stuff over your head. It isn't heavy but holding and attaching at the same time is a pain in the rear.
post #11 of 21
Quote:


It isn't heavy but holding and attaching at the same time is a pain in the rear.

True. My drywall lift came in VERY handy for this.
post #12 of 21
Thread Starter 
Quote:
Originally Posted by tlogan6797 View Post

This is probably one of the easier projects to DIY.

First, go to your local big box store and stroll the HVAC supply aisle. See what they have. You should be able to get the rectangular ducts that come in two "L"-shaped pieces. You assemble the two pieces into a rectangle.

You'll want to buy a few tools....heavy gloves and a set of tin snips. You should be able to find a set of three for right, left and straight cuts. They don't need to be really expensive, this is probably a one shot deal. Silver duct tape, NOT DUCT TAPE Brand. Surprisingly, Duct Tape brand CANNOT be used on ducts. And you'll want some way to hang the new ducts. Look at how your existing ducts are hung and do the same thing. (At my house, they just cut thin strips of sheet metal and bent them to make hangers.) You can extend the round the ducts with flex ducts. THey come in a box usually 25 feet long.

Then it's pretty much like putting the pireces of a puzzle together. If you can't find the 45 degree bends at your local bog box (or any other parts for that matter), try an HVAC supply house. Fit the pieces and seal with the tape.

And don't be surprised if you need to make trips to two stores to get everything you need. My biggest pet peeve during my looooong build is that I can't go to one big box and get EVERYTHING I need, especially for the HVAC and plumbing projects.

Since this is your first project like this, I would build everything along the new wall towards the connections and then do the actual connections last. It seems to always take longer than you think. You don't want to disconnect the a main trunk, be without heat and then run into a problem and have your main trunk disconnected.

One more thing since you are going to the effort of moving the main trunk. Maybe you want to think about doing this AFTER the ceiling is drywalled. That will help a lot with sound proofing. You want to completely contain the trunk inside the soffit.

Good luck!

great explanation, sounds easier than I imagined but we'll see once the sheet metal starts flying. Can you elaborate on what I bolded? I can't picture what those pieces are.

Quote:
Originally Posted by RPh Drew View Post

As suggested, use the radius corners and not abrupt 90 degree corners to maintain air flow. This may be a DIY project but not necessaraly a do-it-by-yourself project. An extra set of hands is invaluable when trying to hang this stuff over your head. It isn't heavy but holding and attaching at the same time is a pain in the rear.

this is certainly a "call that buddy who owes you one" project. Are the radius corners 45 degrees?
post #13 of 21
Like I said above and linked to.....



You can get these in 45 degree or 90 degree, and get custom anywhere in between if you find a fabricator to do it.
post #14 of 21
Quote:


You should be able to get the rectangular ducts that come in two "L"-shaped pieces.

The pieces are L-shaped to the width and height you want. Ther eare sevcerla standard sizes available. Then you put the two together to make the rectangle. You lay one down with the short part facing up, then put the other over top with the short part facing down. Like this....

...............____ .......____
|____.........|.........= |____|
post #15 of 21
Quote:
Originally Posted by tlogan6797 View Post

One more thing since you are going to the effort of moving the main trunk. Maybe you want to think about doing this AFTER the ceiling is drywalled. That will help a lot with sound proofing. You want to completely contain the trunk inside the soffit.

Logan made a good point, check your local code, in my township, soffit need to be fireblocked too if it is next to the foundation wall, 1/2" drywall in between the joist and soffit will do. Do it before moving the duck is much easier, and also, insulate rim joist prior to the fireblocking and duct moving too.
post #16 of 21
Find out the cost of all this stuff you need to do it on your own before doing anything. Moving a trunk adding dampers @ takeoffs, duct sealing the joints, and linocoustic line the trunk/trunks. I would be willing to bet you would only save $200-$300 by doing it yourself. Despite the very cold weather as of late. This is the mid season and a good time to get great deals.

Oh and moving that line set for the AC would be hard to do it right. Unless you want to buy a vacuum pump for a couple of hundred bucks.
post #17 of 21
Just spoke to my HVAC guy today about moving my supply trunk.

He said it would be around $1000, not much less, if at all. That's for about 10 hours of labor and minimal materials. If you did the work yourself, my guess is that you could save probably $700 or more.

However, he did say that any 90-degree turn would dramatically reduce the output and throw the balance way off. He said they may have to come back and install additional dampers in various sections.

I haven't decided whether or not it's worth the effort. Worst case if you do it yourself, though, is that you probably wouldn't mess it up beyond an experienced HVAC installer to repair. So really you don't have much to lose by trying it yourself.

I should say that you probably need at least one or possibly two other people helping. It's definitely not a 1-man job.
post #18 of 21
Quote:
Originally Posted by Drew_V View Post

Just spoke to my HVAC guy today about moving my supply trunk.

He said it would be around $1000, not much less, if at all. That's for about 10 hours of labor and minimal materials. If you did the work yourself, my guess is that you could save probably $700 or more.

However, he did say that any 90-degree turn would dramatically reduce the output and throw the balance way off. He said they may have to come back and install additional dampers in various sections.

I haven't decided whether or not it's worth the effort. Worst case if you do it yourself, though, is that you probably wouldn't mess it up beyond an experienced HVAC installer to repair. So really you don't have much to lose by trying it yourself.

I should say that you probably need at least one or possibly two other people helping. It's definitely not a 1-man job.

Drew,

If it is return trunk, then you can use joist cavity as connecting trunk, but it is supply, the HVAC guy is right, you don't want to reduce the air flow. One thing you probably can do is to increase the size of the turn, something like this may helps. Size of supply and return trunk should be properly balanced, they put in the middle of the basement for a reason, that is to distribute and circulate air inside the house evenly, if you move supply to one side, then one side of the house may heat or cool more quickly than the other side. Same as to the return trunk, when I moved mine, I was worried one side of the house will be cooler or hotter than the other side since the air will be sucked back more quickly on the side that the return trunk was moved to. So I have to increase the size of the return trunk by using couple of more joist cavity to balance out. I am not sure in your case, you should do the opposite, to reduce the return trunk size to increase the air circulation on the other side? I am no expert, but some knows better can explain.
post #19 of 21
2panther -

I ended up redoing pretty much all of the main and branch trunk lines as part of my basement build. Sorry but I only have about a few poor pictures but based on my experience can offer a few pointers. First is that the local DIY home stores are severely lacking in HVAC parts. You are way better off finding an HVAC supply. I found one that was surprisingly close to my home, had an online catalog, and I just called in my order and picked it up. Doesn't get much more convenient then that and they had about every size and shape of trunk lines and elbows available. Surely there is a place nearby you that has the correct size trunks to match your existing ductwork. Second is that I knew from living in the home for awhile where my current ductwork was lacking and actually was able to more evenly distribute the HVAC through my work. You asked about the effect. The trunk you want to move, does it already heat/cool well or is it somewhat lacking? If it already heats/cools very well then adding two 90 bends and lengthening the run may not have a detrimental effect. But if it is already lacking then you are going to make it worst. Finally this PDF was very helpful for me in understanding how the ductwork is put together and lacking detailed load calcs what general rules of thumb can be followed - http://www.alpinehomeair.com/related/Ductwork.pdf. Like anything DIY, with planning and prep you will not have a problem.
post #20 of 21
I am NOT a practicing engineer, however schooling teaches you that the pressure drops produced with introducing angles (additional skin friction) would be alleviated by using a larger inner diameter duct for the trunk. There are probably fairly simple calculators available for HVAC techs that you can use. These easy equations would be derived from the more difficult but accurate theory. I would ask you local HVAC supply house (if you were to buy from them) to help you with the calc's.
post #21 of 21
Thread Starter 
Quote:
Originally Posted by D-Train View Post

2panther -

I ended up redoing pretty much all of the main and branch trunk lines as part of my basement build. Sorry but I only have about a few poor pictures but based on my experience can offer a few pointers. First is that the local DIY home stores are severely lacking in HVAC parts. You are way better off finding an HVAC supply. I found one that was surprisingly close to my home, had an online catalog, and I just called in my order and picked it up. Doesn't get much more convenient then that and they had about every size and shape of trunk lines and elbows available. Surely there is a place nearby you that has the correct size trunks to match your existing ductwork. Second is that I knew from living in the home for awhile where my current ductwork was lacking and actually was able to more evenly distribute the HVAC through my work. You asked about the effect. The trunk you want to move, does it already heat/cool well or is it somewhat lacking? If it already heats/cools very well then adding two 90 bends and lengthening the run may not have a detrimental effect. But if it is already lacking then you are going to make it worst. Finally this PDF was very helpful for me in understanding how the ductwork is put together and lacking detailed load calcs what general rules of thumb can be followed - http://www.alpinehomeair.com/related/Ductwork.pdf. Like anything DIY, with planning and prep you will not have a problem.

outstanding document, really explains it in normal terms. Thanks for posting it.
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