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HVAC Forums => HVAC Help => Topic started by: edee_em on November 24, 2020, 01:12:33 PM

Title: air return to nowhere
Post by: edee_em on November 24, 2020, 01:12:33 PM
Hi. Hope everyone is safe and well.

I discovered an air return from upstairs bedroom that does not connect to the air return ducting going to the furnace. It is one joist bay over from where the ducting is.

I was thinking the easiest solution would be to drill some holes into the joist blocking the path to the return duct and then put in some blocking to create a path. I also know that this solution is probably the one with the most danger in that there might be a comprising of the joist (2x8" 16 oc). Does anyone know how much material can be taken out of the joist? Is it better to drill holes or cut out a rectangle? Things like that... Thanks

Also, I'd be interested in hearing on what you guys have been doing in the field when you come across this type of issue.
Title: Re: air return to nowhere
Post by: Admin on November 24, 2020, 03:03:18 PM
Post a pic so I can see the type of joist you have and how close point loads are.  Click additional options below to upload a pic.

If the joist has an aspenite middle then you can cut out a square or round hole as long as you leave at least 1/4" of aspenite below and above the hole.  To be safe if the duct is 6" I would stay 6' away from any point loads before cutting a hole through the joist.  If it's a 5" duct then stay 5' away.
Title: Re: air return to nowhere
Post by: edee_em on November 25, 2020, 10:31:45 AM
Not having any luck attaching a pic. I chose it under Attach, the file shows up but there's no way to actually attach it. What am I missing? I reduced the file size to icon size but that didn't seem to help.
Title: Re: air return to nowhere
Post by: edee_em on November 25, 2020, 10:32:39 AM
Whooooopppppppsssssss! Please let me know if you need any clarification.
Title: Re: air return to nowhere
Post by: Porcupinepuffer on November 25, 2020, 06:39:04 PM
I'd typically put in a square transfer duct with two block ends right alongside the metal beam to catch each joist space. I would do it with a section of 8 x 8 duct... But this also depends on if the area is finished and if you're particular about not losing any additional ceiling height with an extended bulkhead... But when you already have a steel beam right there, it's usually not a big deal for most customers.
Title: Re: air return to nowhere
Post by: edee_em on November 25, 2020, 07:01:12 PM
Thanks Porcupinepuffer. So it would be 32" across to get both joist bays and 8" deep? Does it need to be that deep?