Return Air Baffle for CV1800

[Bryan Cleveland]

I’ve been designing a closet for my CV1800 for a few months trying to find a way to make it fit in my little garage and I think I have finally cracked it. My only concern is with the return air baffle I designed.

Garage is air conditioned so return air is a must. I’ve read so many posts about closets on this forum alone but just want some outside opinions.

In the attached pics you will see the closet and the air baffle I am currently planning on. Nothing is built yet.

The interior dimensions for the air baffle are as follows: 26” wide x 3.25” tall. The air path has (4) 90 degree turns. Does this look like it will work for me?

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[Jamie Buxton]

Can you line the interior walls with something soft and fluffy? That will absorb high frequency sounds. For instance https://www.distributioninternational.com/insulation/fiberglass/fiberglass-blankets

[Bryan Cleveland]

Oh yeah there’s quite a bit more going on inside the closet than pictured. I’m going to purchase a scratch and dent prehung door. Steel or fiberglass insulated. I’m going with a layer of 5/8” drywall on the two corner walls which already have 5/8” drywall installed and insulated. On the Inside of the same corner I’m thinking of using some mass loaded vinyl possibly or foam. Not sure yet.

As for the two portions either side of the door frame I’m going with 3” insulation, again haven’t decided yet. I am planning to line the interior with pegboard rough side facing out. A guy named Jim I think did that on his. Also borrowed his air baffle design and tweaked it to work with my setup. Thanks Jim. Exterior portions double layer of 5/8 drywall. Green glue sandwiched in between.

I’m going up to my existing ceiling that already insulated and has 5/8” drywall. Planning to seal it up good and pray that makes a noticeable difference and if it doesn’t I’ll be back on here hoping for some ideas. I’d like to use some of this stuff but it’s not in my budget. I could afford 1 sheet but no more.

[Jamie Buxton]

Sorry, I wasn't clear. I meant for you to line the baffle.

[Bryan Cleveland]

Oh never thought of that. I was checking out the link you provided see what all they had. If I do line the baffle do you think it will restrict the air flow?

[Jamie Buxton]

Oh never thought of that. I was checking out the link you provided see what all they had. If I do line the baffle do you think it will restrict the air flow?

Yeah, all that other stuff you've mentioned acts upon sound which is already has to be fighting its way through walls and floors and such. In contrast, the return air baffle has unobstructed passage for sound. So treating as best you can is a good thing.

The lining would be reducing the cross sectional area of the baffle, so that's an issue worth considering. Without any lining the baffle has a cross section of 26x3.25. With, say, 1/2" thick lining, you'd be down to a cross section of 25 x 2.25. The cross section area is then 56 square inches. If your main duct into the closet is 6" diameter, its cross section is 28 square inches. That is, the dominant air resistance in your system would still be the input ducting, not the baffle at the exit.

[Jamie Buxton]

Or maybe you could move the baffle to that wall below the input duct. That would seem to offer a lot more space than the above-door location, so you could make the baffle cross section bigger.

But I gotta admit I'm concerned about wrestling the cyclone into place. Mine is smaller than yours, and it was quite a fight. Maybe you make the baffle removeable -- that shouldn't be too hard. Then you can install it after the cyclone, and uninstall it if you need to pull the cyclone out.

[james manutes]

My return air passes thru 2 12 x 24 filters , trying to keep the mini split as clean as I can .

[Leigh Betsch]

I don’t have a return baffle but I do have a filter plenum. I lined that with old shag carpet as recommended to reduce noise. I don’t think it made a ton of difference. But my cyclone is in an upstairs attic so most of the noise is already filtered by the ceiling.

[Jim Becker]

That's not unlike the solution I did at my old shop and will do something along the same lines for the new shop. One suggestion is for you to put it down low to further reduce any direct noise transfer. Right now it's parked in front of the motor and blower and while the baffle will substantially reduce the sound anyway, you may get a better result with it farther down on the wall or farther up in the ceiling.

[Rush Paul]

Nice design on the baffle. For the baffle in our shop, we glued and screwed some wall-to-wall pile carpeting (about 3/8-1/2" thick) to the inside walls. Doesn't take up much interior volume and seems to have worked well in damping the noise a bit further than without it.

[Bryan Cleveland]

That's not unlike the solution I did at my old shop and will do something along the same lines for the new shop. One suggestion is for you to put it down low to further reduce any direct noise transfer. Right now it's parked in front of the motor and blower and while the baffle will substantially reduce the sound anyway, you may get a better result with it farther down on the wall or farther up in the ceiling.

Jim it was your design I took from. I will play around with my 3d model and try putting it on either side of door frame. Guess as long as I stay larger than the outlet on the blower housing I should be fine.

I made the entire shop layout on my iPad using shaper3d. So far everything I’ve designed and built or had built has been right on. Ok y’all get back to you after work.

[Rush Paul]

Bryan, the information about sizing I've seen in the Australian Woodworking Forum (lots of information on dust collection) is to shoot for a baffle area that is 2x or greater than the outlet from your blower housing. Also, one advantage to keeping the intake for your baffle up high will be that air inside you closet will be forced up and around the motor to help with cooling the motor.

[George Yetka]

I would find a way to incorporate a cheep dust filter. The clearvue will pick up most dust but the clean air will still move the air in the closet which im sure will be dusty.

[Frank Pratt]

By the time you line the return air with 1" acoustic duct liner (definitely want to do that) you will not have a lot of cross sectional area. With that many bends, I would want to have at least 2X the area of the inlet, more if possible. My return is 29.5" x 12" (or there about) and has a 90* and 2 45* bends. It works very well. Yours will block even more sound.

[Bryan Cleveland]

Jamie. I never mentioned it but my plan is to either build a floor standing frame to support the cyclone or utilize cushioned suspension isolators from my ceiling joists directly above. The. Build the closet around the cyclone and frame. Definitely would not want to try handling the cyclone in the closet.

I have a little time today so I’m going to go back to my 3d model and make some changes. Stay tuned. Thanks for all the input.

[Jamie Buxton]

Jamie. I never mentioned it but my plan is to either build a floor standing frame to support the cyclone or utilize cushioned suspension isolators from my ceiling joists directly above. The. Build the closet around the cyclone and frame. Definitely would not want to try handling the cyclone in the closet.

I have a little time today so I’m going to go back to my 3d model and make some changes. Stay tuned. Thanks for all the input.

If you build the closet around the cyclone, can you assemble the closet with screws? I'd hate to build the closet, and then some day down the road need to service the cyclone.

[Jim Becker]

If you build the closet around the cyclone, can you assemble the closet with screws? I'd hate to build the closet, and then some day down the road need to service the cyclone.
Very valid question, Jamie. It shouldn't be an issue building things with screws to permit disassembly unless there is a bearing wall involved.

[John K Jordan]

I built a return air duct for my 5hp clearvue. Used 1/2” plywood, had it extend up into the roof trusses, made several turns and added a couple of baffles to disrupt the sound path. I calculated the air volume and made it oversize to minimize any back pressure possibility. I insulated well around the outside of duct and sprayed a rubber coating everywhere inside. I can’t detect significant sound at the exit point in the main shop. With the insulated closet I can hear a whisper outside the closet when running. Sounds like a jet engine inside the closet.

[Bryan Cleveland]

Yes I will definitely be building with screws. Crappy part is that the bottom plate will either have to be attached to the garage floor with either construction adhesive(not a lot, but enough) or probable tapcons. My foundation is post tension and I was advised by the builder to not drill into the concrete. However I have read that the cables are several inches below and as long as I don’t it plastic I’m not close to the cables. I figure a tapcon screw a couple 2-3 inches should be ok.

George, good thinking. In my design I incorporated a 1” cut to size filter. It’s in dark blue behind the expanded metal door I’ll need to build. It’s on hinges and will latches and a foam edge type gasket. I have one like it on the inlet of my mini-split and it’s great for catching dust. Should definitely help. Ok so here is the design 2.0 I’ve come up with. What I would not give for another couple feet length and width in the garage. There’s lots you cannot see that are not easily relocated items in the garage. Gotta work with what I have. I am very thankful to have it. So hit me with it what do y’all think? Is it enough? Oh and the yellow you’ll see is 1” acoustic fiberglass.

That’s was good thinking Jim mentioning exhaust air entering from bottom and not top. Makes perfect sense.

close to the cables. I figure a tapcon screw a couple 2-3 inches should be ok.

George, good thinking. In my design I incorporated a 1” cut to size filter. It’s in dark blue behind the expanded metal door I’ll need to build. It’s on hinges and will latches and a foam edge type gasket. I have one like it on the inlet of my mini-split and it’s great for catching dust. Should definitely help. Ok so here is the design 2.0 I’ve come up with. What I would not give for another couple feet length and width in the garage. There’s lots you cannot see that are not easily relocated items in the garage. Gotta work with what I have. I am very thankful to have it. So hit me with it what do y’all think? Is it enough? Oh and the yellow you’ll see is 1” acoustic fiberglass.

That’s was good thinking Jim mentioning exhaust air entering from bottom and not top. Makes perfect sense.

I will definitely be building with screws. Crappy part is that the bottom plate will either have to be attached to the garage floor with either construction adhesive(not a lot, but enough) or probable tapcons. My foundation is post tension and I was advised by the builder to not drill into the concrete. However I have read that the cables are several inches below and as long as I don’t it plastic I’m not close to the cables. I figure a tapcon screw a couple 2-3 inches should be ok.

George, good thinking. In my design I incorporated a 1” cut to size filter. It’s in dark blue behind the expanded metal door I’ll need to build. It’s on hinges and will latches and a foam edge type gasket. I have one like it on the inlet of my mini-split and it’s great for catching dust. Should definitely help. Ok so here is the design 2.0 I’ve come up with. What I would not give for another couple feet length and width in the garage. There’s lots you cannot see that are not easily relocated items in the garage. Gotta work with what I have. I am very thankful to have it. So hit me with it what do y’all think? Is it enough? Oh and the yellow you’ll see is 1” acoustic fiberglass.

That’s was good thinking Jim mentioning exhaust air entering from bottom and not top. Makes perfect sense.

[Bryan Cleveland]

Ok y’all I gotta run. John I’ll get back to you on that. I’m liking the sound of that. Forgot the dimensions. It’s constructed from 1/2” mfd. Interior dimensions are 7.5” x 68.75” x 7”. Up where the air makes a u-turn is 9ish” over the wall coming out the blue filter which is 7x 70” I think. Later y’all. More tomorrow.

[Jeff Bartley]

Bryan,
A post tension slab?! Wow, I’ve never seen one of those in residential construction. What’s under your slab? I would definitely not drill into that slab anymore than I’d drill into a hydronically heated slab.
You’ll love having your cyclone in a closet. I had mine in an enclosure at my old shop and still haven’t built a closet around it in my new shop. The sound kinda makes me crazy by the end of the day!

[Bryan Cleveland]

Jeff to be honest I have no idea what under the slab. During construction I saw a grid of trenches dug down several feet. 4-5 feet u guess. Inside the grid were large squares covered with tarps. Dirt or something. Then they poured concrete I assume.

I’ve done a lot of reading. I typically over think things. Actually everything. I do the same with research. Lot of reputable pros in various construction trades have mentioned a special concrete anchor with a drill stop permanently attached that only allows a couple inches or so for just this purpose. I figured an inch or two with a tap on that I can remove at a later date should be ok. However. I think I’ll contact my builder and ask them if I’m safe doing it. If not ok I’ll use construction adhesive. Will take lot more effort to remove but doable.

[Thomas Wilson]

I have my dust collector below my shop with just the stairwell as a return. (This is temporary.) When the DC is running, the return flow pushes the door at the top of the stairs open 6 inches or so. That gives a flow area estimate with little back pressure of about 80”x6”. I will be working to get close to that when I put in my return. I have an Oneida Smart Gorilla Pro 5hp.

[Jim Becker]

If I'm not mistaken, post-stressed/tensioned slabs have cables in them that are tightened after the pour is cured. I remember seeing that on an episode of the BuildShow on the 'Tube awhile back on a "yuge" residential project...assuming my memory isn't flawed. While I doubt the short fasteners used to anchor a wall to the slab would be an issue, I'd want to check with the experts on that before drilling hole number one.

[Frank Pratt]

If you do drill into a post tension cable and break it, you'll know right away. Post tension slabs just aren't used anymore in these parts because repairs for corrosion, when (not if) it happens, are extremely expensive. There have been many otherwise good buildings demolished because it was not practical to repair those cables.

[Malcolm McLeod]

Yes I will definitely be building with screws. Crappy part is that the bottom plate will either have to be attached to the garage floor with either construction adhesive(not a lot, but enough) or probable tapcons. My foundation is post tension and I was advised by the builder to not drill into the concrete. However I have read that the cables are several inches below and as long as I don’t it plastic I’m not close to the cables. I figure a tapcon screw a couple 2-3 inches should be ok. ...


Bryan,
A post tension slab?! Wow, I’ve never seen one of those in residential construction. What’s under your slab? I would definitely not drill into that slab anymore than I’d drill into a hydronically heated slab.
...

Continuing the hijack, just a little... Slab on grade with post-tension cables (PTCs) is essentially the standard in N.TX, and has been for 30-40yrs now. Early on, the bottom plates were typically attached w/ ramsets, but I'd say 99% are now 'bolted' down w/ wedge anchor's (better resistance to tornado lift, IIRC). Neither method impacts the PTCs. (Mr. Cleveland's description below makes his sound like what would be called a box beam slab here, and PTC's are optional ...depending on all the usual factors.)

PTCs are simple to repair: I'll spare y'all the lead-up (!plumber!), but last house had a cable break during construction. Most of the cable popped out and was laying in the yard; lubed plastic sheathing was still in the slab. It took a 3-man crew <1 hr to pull the new cable in, stretch it, crimp the ends, and a schmear of grout on slab edge to hide the cable ends.

Bottom line, I'd place the plate, drill thru and into slab, then insert 3-3.5" wedge anchors (~1.5" in concrete). In case it helps, I've done it several times.

[Frank Pratt]

PTCs are simple to repair: I'll spare y'all the lead-up (!plumber!), but last house had a cable break during construction. Most of the cable popped out and was laying in the yard; lubed plastic sheathing was still in the slab. It took a 3-man crew <1 hr to pull the new cable in, stretch it, crimp the ends, and a schmear of grout on slab edge to hide the cable ends.

It's a whole other matter in a commercial building where the cables have corroded. It almost always involves excavating the cables at 1 or more placed along the length of the run so they can get the old out and new in. We do a lot of work for 4 different concrete restoration companies that do PTC repairs. They inevitably break into electrical conduits in the slab and we get a call to repair them. It's mostly in parking structures where there is salty run off from the cars.

[Bryan Cleveland]

Haven’t forgotten about this thread. Been super busy. Trying out some designs.

[Bryan Cleveland]

Think I need some help here. What would be the ideal dimensions for return air flow to exit the closet? Minus insulation.

I have created around 20 different designs for return air that I eventually shoot down for one reason or another.

Starting to think I should have just sold the dust collector and bought the G700 from Harvey. Unfortunately it’s too late for that as I’ve already spent money to move the mini split over(utilizing the same pass thur hole in the wall).

I have been working on this closet design for months trying to make it fit my space. This air return is the last piece of the puzzle. I have been trying to stay above 8” x 8” but with insulation and or baffles it keeps getting bigger and bigger. Blocking access to the filter stack. Any thoughts?

[John K Jordan]

I measured the area of the cyclone exit duct and designed my return duct so it had no restriction with a smaller area. To err on the safe side and allow for inefficiencies from the turns and such I think I made it about 20% larger. The shape of the duct doesn’t make a lot of difference. (unless perhaps it was extreme)

[Chris Parks]

Think I need some help here. What would be the ideal dimensions for return air flow to exit the closet? Minus insulation.

I have created around 20 different designs for return air that I eventually shoot down for one reason or another.

Starting to think I should have just sold the dust collector and bought the G700 from Harvey. Unfortunately it’s too late for that as I’ve already spent money to move the mini split over(utilizing the same pass thur hole in the wall).

I have been working on this closet design for months trying to make it fit my space. This air return is the last piece of the puzzle. I have been trying to stay above 8” x 8” but with insulation and or baffles it keeps getting bigger and bigger. Blocking access to the filter stack. Any thoughts?

I would bet good money the Clearvue would blow the doors off the Harvey performance wise, no contest at all.

[Bryan Cleveland]

Here is what I have finally come up with. Skinny rectangular box is 5”x36”. 1/2” material. Interior 4” x 35”. Cutout on bottom is approx. 6” above floor. Exhaust air flows down to cutout, up into the box to the right hand upper corner. Hard 90 degree turn into a 10” insulated duct and passes thru a 1” thick 12x24 air filter.

I want everything contained in the closet and have so many obstacles in my way. I think this is the best I can do. Lost count how many 3d models I have created and then deleted as I found problems with. If this doesn’t work I’m probably gonna sell my cv1800 and get something else. Hope this works. Thought?

Here is the room.

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