[shorehome]

greetings.

I had a contractor relocate my attic air handler, supply and return ductwork and some registers during my home renovation.

The hvac contractor relocated a return grill in the 2nd floor hall, which was great. He also utilized an existing return shaft that goes to my 1st floor, but he had to connect this return shaft to the relocated air handler. Long story short, the return flex leaves the air handler and penetrates the subfloor near the air handler, in the bay that leads to the return shaft. However, there is nothing connecting the flex pipe to the return shaft - there is sheetrock, joists and an old plywood subfloor acting as my ductwork. There is a space of about 12 feet from the flexpipe to the shaft. The top of the shaft was covered with a piece of sheet metal nailed into the subfloor.

To me this seems just plain stupid and we spent a summer drawing hot, stale, dirty subfloor attic air into our system. I am going to try to get him back in, but in case he does not come back or in case I do not want him back, do you think there enough room to add ductwork and insulate under the subfloor to close the circuit? - 2x8 joists.

:jester: :furious:

 

[Marty S.]

No. Eight inches is not enough for duct and insulation.

 

[shorehome]

No. Eight inches is not enough for duct and insulation.

Marty, thanks - I had that feeling.

Assuming the current "configuration" is not correct, and that I cannot run a soffit on the ceiling below, and I do not want to compromise attic floor space - which was the whole reason we moved the unit - and assuming I do not at this point want to relocate the return shaft to a more appropriate location....

What if I line the bottom and sides of the bay with sheet metal and add a metal cover say 6-6.5" high, connect each end to the flex and to the shaft and then spray foam the top as much as possible before replacing the subfloor?

I can deal with a low amount of insulation in this one bay, but I do not want to over-restrict the airflow to the handler. Given that we have 2 returns --- probably ok ??

I know I am leaving out some important info about the handler but I am not home now.

 

[bobinphx]

The only way to really tell is to check the static pressure and air flow. your installer will need an manometer and an anomometer. Specs for what is acceptable provided by the mfgr (static) and hvac standards (300-400 fpm at return).

Running returns in stud or joist bays is acceptable, if the sizing is correctly matched to the air handler. But having wiring or pipes etc might be an issue.

you might really need to get creative in order to fix this!!! pictures or a drawing would be a help.

 

[shorehome]

Hi Bob - sure, I have been meaning to post the pics. I really want to throw up the more I look at these. Anyway, yes creative is good. I am leaning toward turning the bay into a duct with sheet metal, with an inch of clearance on top for spray foam.

I think there is enough room for adequate airflow given the size of the existing opening in the vertical shaft to the 1st floor before the unit was moved vs. now (not much difference in area - this assumes the old configuration was good). Honestly, the system has 2 returns setup and the new 2nd floor return is larger than the old 2nd floor return as well.

That's what I am thinking, just a matter of connecting the flex to the vertical shaft within the confines of the bay. Luckily there is nothing obstructing the bay, to your point regarding pipes and studs.

What do you think? Pics:

http://s1283.beta.photobucket.com/user/shorehome/media/photo2_zps31fa20d4.png.html?sort=3&o=0

http://s1283.beta.photobucket.com/user/shorehome/media/view_from_shaft_zps2f4457f8.jpg.html?sort=3&o=1

 

[Technow]

Hi Bob - sure, I have been meaning to post the pics. I really want to throw up the more I look at these. Anyway, yes creative is good. I am leaning toward turning the bay into a duct with sheet metal, with an inch of clearance on top for spray foam.

I think there is enough room for adequate airflow given the size of the existing opening in the vertical shaft to the 1st floor before the unit was moved vs. now (not much difference in area - this assumes the old configuration was good). Honestly, the system has 2 returns setup and the new 2nd floor return is larger than the old 2nd floor return as well.

That's what I am thinking, just a matter of connecting the flex to the vertical shaft within the confines of the bay. Luckily there is nothing obstructing the bay, to your point regarding pipes and studs.

What do you think? Pics:

http://s1283.beta.photobucket.com/user/shorehome/media/photo2_zps31fa20d4.png.html?sort=3&o=0

http://s1283.beta.photobucket.com/u...ew_from_shaft_zps2f4457f8.jpg.html?sort=3&o=1

Ductwork takes space...I see the type of work in your pics everyday, its not right but its what the builder paid for when the house was built. Typically causes poor performance and shortened equipment life.


Key points:
1. ductwork takes SPACE.
2. If it were my house, I would put the proper sized duct to the return and then cover it up with a hard cover to be able to stack stuff on top of it.

 

[shorehome]

Ductwork takes space...I see the type of work in your pics everyday, its not right but its what the builder paid for when the house was built. Typically causes poor performance and shortened equipment life.


Key points:
1. ductwork takes SPACE.
2. If it were my house, I would put the proper sized duct to the return and then cover it up with a hard cover to be able to stack stuff on top of it.

well, for the record, it is not what a builder paid for, it is what I paid someone to do the right way, and instead they did what is in the pictures.

yep - ductwork takes space. the key question here is, can I fit something that will work well enough under the floor. I would even consider using the next bay as a second path to the vertical shaft to improve airflow if necessary. Having ductwork above the floor here is not what I want - I would almost rather move the vertical shaft.

 

[Technow]

well, for the record, it is not what a builder paid for, it is what I paid someone to do the right way, and instead they did what is in the pictures.

Probably did what you told him: Did you tell him to keep it under the floor? I would have told you NO, I am not doing that, however, maybe he was the cheapest and needed the work - I don't know



yep - ductwork takes space. the key question here is, can I fit something that will work well enough under the floor. I would even consider using the next bay as a second path to the vertical shaft to improve airflow if necessary. Having ductwork above the floor here is not what I want - I would almost rather move the vertical shaft.

What part of DUCTWORK TAKES SPACE- you don't understand?- Pick a reasonable solution to get the required size from the return to the unit. Move the return. Move it up and over, doesn't have to move along floor. Running duct thru bays is just terrible and not the first solution. Are you putting a bowling alley up there and need the floor perfectly flat?

 

[shorehome]

What part of DUCTWORK TAKES SPACE- you don't understand?- Pick a reasonable solution to get the required size from the return to the unit. Move the return. Move it up and over, doesn't have to move along floor. Running duct thru bays is just terrible and not the first solution. Are you putting a bowling alley up there and need the floor perfectly flat?

Thanks for your input. I would appreciate it if you would not continue to post in this thread.

Anyone else capable of thinking outside the box that wants to discuss, please feel free to step in.

 

[Technow]

Thanks for your input. I would appreciate it if you would not continue to post in this thread.

Anyone else capable of thinking outside the box that wants to discuss, please feel free to step in.

It would be more helpful if you defined the box we have to stay out of and why. Why can't you go up and over? Keeps the floor flat. Sorry if I offended you, duct space is a battle we have to fight everyday trying to balance performance with lunacy.

For Example: How much air are you trying to move?

 

[bobinphx]

dudes... mellow out... no need to get upset.. its just a duct run!!!!!

I think we all agree that its not right and needs to be fixed...

so now how do we do this... hhhmmm

your existing joist space is too small and I have reall issues with the bend in the flex at the far end of the pictures...

could you span two joists???? this looks like an attic with a floor... what if you put the flex duct directly above on of the joists and then put ducts (real steel ones) in each of the spaces... sort of splitting the air path over two joists.. I cant really see the other end (camera end)

I do see the need to insulate if this is in an uninsulated attic.

since you dont want a duct running across the floor, what about one up high???? could you run that flex up and over the area you want to keep clear???

 

[shorehome]

Hi - no worries, I appreciate the feedback from everyone. I will put my internet emotion filter on. I did pretty much set the definition for what I was looking for - both to the original contractor and in this message - that is, I want the floor clear to maximize future finished livable space, I did not provide guidance to do things the wrong way to accomplish that goal. The correct solution I think would have been to move the shaft - but that ship has sailed.

So, the options are:
1) up and over, and down with a vertical metal shaft - box it out - this could work, but could limit the options of the final attic space.

2) keep it under the floor. I think this could work if we split the return into two bays and have each attach the the existing shaft. We would need to cut the second joist to make the shaft connection. I like this option better. Not sure how to get around the bend in the flex, as there has to be a bend somewhere to get under the floor, right?

Remember, there are two returns. The second return is totally fine, closer the the handler, and a good size. I think the unit will get enough air even with a limited second return - I admit I can be totally off-base here and totally appreciate the feedback.

I will get the unit specs which are being used to cool about 2000-2250 sq ft of total space on two floors (1000sqft-ish per floor) and eventually maybe a supply or two in the finished attic space.

Important to note that I want to eventually seal the attic (in a year or so) with foam at some point (under the roof) - so the insulation in the floor may not be so critical in the long run. Just a thought - if the attic is sealed - can the return simply be properly installed in the attic? Not ideal but hmm I never considered this.

thanks

 

[beenthere]

vacuum out cavity. Caulk the joist to drywall seams. Get a roll of reflective bubble wrap. Insulate the joist with a single layer since the other side of the joist is already insulated. Spray glue and staple 2 layers of it on the bottom of the sub floor your gonna lay down. run a bead of caulk on the joist before you lay the sub floor down.

 

[ben's plumbing]

yep just what bt suggest....then your done :thumbup:ben sr

 

[shorehome]

beenthere, thanks I was looking for an idea like that. I will try that and have the airflow tested, but I am pretty confident we have a better total return capacity than before the renovation - not that that means anything.

now, to deal with the bozo that installed my master bathroom vent fan and left it blowing into the insulation. trust... never use it with builders and contractors.