joist to joist return connection

[cobra888]

I want to run a new return on an addition to my house (new heat was added but no new returns!). I want to pan out along joists to the new section, but to get from where I want to connect to the return trunk to where I want the return register, I need to shift along the route from one joist to its neighbor. Is there an existing connector out there to do this. Essentially, I want to drop down, over and back up to the neighboring joist.

thanks for any help

[coolwhip]

Sounds like you need to have some panning made up to cross over. Either that, or chop the joist out.

[northof49]

I wouldn't "chop" the joist out.

There is a formula for the size and amount of holes that you can drill or cut into a joist. Find out what that is and then drill those holes out. You might have to do it over a 6 or 8 foot span. Follow me?

Or you could go to a tin basher and have that connector made that you were talking about. It would be pretty simple to do it either way. The only problem with the connector is you would lose some head room.........but that may not be a concern that you have.

North

[tinknocker service tech]

ost bays are 14 by 8 or 10
a piece of duct with both ends capped off
cut the top out beam to beam and put it up to the bays you are jumping. beam caps will be need to seal the open side of the bay

[coolwhip]

Just kidding about chopping the joist

[docholiday]

Yeah no chopping....... but a bunch of 2" holes might be ok. As mentioned you cant go crazy with them.

[Irishmist]

Geesh guys, did everybody forget what to call a 'jumper?' I wouldn't suggest a DIY start hackin' away at ANY structural support of the home. There are proper ways to accomplish this and a competent contractor can provide you the proper method and size you need. I don't know about the rest of you, but this is a fairly common practice here when plumbing, or joist direction, creates the need to 'jump' from one joist space to another. Let's see, lose headroom............or...............affect structural integrity of home. Lemme think............

[docholiday]

Round holes (not square)per an engineer (let him tell you) dont jeopordize the integrity of the joists but Jumper ducts do increase the static, they are loaded with equivilent feet. A 3 foot jumper duct could, without looking, equal as much as 50 feet of duct.

[cobra888]

Thanks for the help. I don't have a head room issue and I don't want to touch the joists. I like the section of duct with the ends capped and the top open suggestion.
thanks again for the ideas...

[Irishmist]

cobra: for the record, that is referred to in the industry as a 'jumper.'

Doc. you tellin me that a 3' jumper is equivilent to 50' of straight duct....... on a return?

[docholiday]

Its not the duct, per say, it's the restriction and turbulance caused by 4 90 deg turns with no vanes that gives it the same restriction as 50 feet of duct. (it may be 30 it may be 70). And yes, thats what I am saying.

[Irishmist]

fair enough. Thanks Doc.

[tinman]

We usually fabricate a "pan" with a open top and the ends at a 45 degree. I don't much care for duct capped on each end. In a pinch we sometimes make a jumper out of 2X6 lumber with the ends cut at a 45 degree and then nail panning on the bottom. It depends on the situation.

[Irishmist]

fair enough. Thanks Doc. I would think the problem you refer to would not be as much of a problem unless you were attemping to pull your total amount of return through a single space. This return may only account for approximately 1/5 of the total air return.

[jrbenny]

90° adjustable elbow is 10 equivalent feet. So, the jumper would be 41 or 42 equivalent feet presuming you use sheet metal pipe between the elbows.