Need help brainstorming a ventilation system for my garage! [Archive]

View Full Interactive Version Of This Page : Need help brainstorming a ventilation system for my garage!

Solana

2006-01-09, 11:39am

Okay, so not too long aoo, my husband and I bought a house that has an oversized garage AND had a perfect setup for a studio! The previous owners left a long work table in the garage and had a fluorescent light installed in the ceiling just above the table and lots of outlets. Perfect! Well, over several tedious months, I worked to turn that little corner into my lampworking studio. :)

I've completed everything but the ventilation system, and thought I'd ask the pros over here for their thoughts, since it's not as easy as just installing a vent hood.

To better explain my situation, I've attached an image of my garage's floor plan. (I apologize for the crappy image, but I had to do this in Powerpoint since my work doesn't provide us with image editors.)

As you can see, we have a two-car garage on the right side of our house. My studio is located in the upper lefthand corner of the garage. Directly to the right of my table, is the back door, and on the opposite side of the wall from my studio are the stairs leading up to our deck. The only window is located on the opposite side of the garage, next to a car.

First of all, I think I may have a difficult time hanging a hood over my workarea because of the pre-existing fluorescent light. However, I think this is the least of my worries. The next big issue relates to the duct-work related to a vent hood. Let's assume I can hang a range over my torch....where do I vent the "bad air"? I cannot vent the air through the wall behind my studio because of the deck stairs AND because half of the wall is concrete foundation (we live in a walk-out split level home). The one opening near my workarea is the back door, and that cannot be converted to a venting window. I also cannot vent the air through the ceiling above my workarea since our garage is underneath the bedrooms, and thus there is no attic. So...the only other option is to vent the air all the way across my garage to the one window on the right, which may interfere with parking our cars since there isn't that much room between the car and that wall.

So, with all that said do any of you guys have any ideas? I guess I could move the studio to the other side of the garage, but there isn't any lighting or outlets over there. I'm on a budget so doing a complete overhaul of the garage isn't really an option.

When I torch, I have the garage doors open along with the back door which actually produces a TON of air movement since my flame blows around like crazy. As such, would I be safe getting a powerful ventless range or something like that? I don't want to be forced to put another shed in our backyard or to have to go to studio and pay for torch time. I'd rather get my garage set up the best way I can. I know many of you have proper ventilation and may have been faced with some of the same issues I'm having. If you guys have any thoughts or suggestions....I'd greatly appreciate it!

Thanks so much for your time!

Karla

Cosmo

2006-01-09, 12:13pm

Since it's a garage, I'm assuming there isn't a second floor, right? Why not vent it out of the roof? Put a hood over the table and run some ductwork straight up.

You will have to get a vent cover to prevent rain/snow/birds from getting in, but it should work fine. Then just open the window for replacement air.

Solana

2006-01-09, 12:29pm

Cosmo

2006-01-09, 12:35pm

Thanks for the suggestion, Chad, but as I mentioned our bedrooms are located over the garage. We live in a split level and the bedrooms are on the "second" floor witht he garage on the "first" floor. As such, we can't run duct-work straight up. :(

Whoops. Guess it pays to read, huh?

The only option I see (aside from moving the table) is to run the ductwork out the window. You probably wouldn't need that big of a duct. In fact you could probably use flexible ducting. If you do, you need a larger fan than you would for regular smooth ducting. Unfortunately, I'm not the guy to tell you what size and type of fan you need. Hopefully Mike or Dale will chime in soon and let you know.

It shouldn't be a problem to run ductwork, though. In that situation, that's what I would do. You can run it over the door along the wall up at the ceiling. It doesn't matter if the fan is at the hood or at the window.

Solana

2006-01-09, 12:39pm

I think the ductwork to the window option is the only one I have, but like you said....I'm not sure what strength of fan I'd need or how large of duct work I'd need. Hmmmm....a fan near the window....I didn't think of that.

Thanks for your thoughts!

Dale, Mike....any thoughts?

Cosmo

2006-01-09, 12:46pm

Here's what Mike posted in the thread I started about our studio. Obviously I was asking about a lot larger area, but the calculations should be similar.

No - it doesn't really work that way. The size of the fan is dependant on how big the hood is.

For an overhead hood in the center of the room, you are going to need about 125 CFM per square foot of hood coverage.

I assume you are going to use a table or two tables side by side to mount the torches on, correct? Let's assume you are going to use 2 tables, each table measures 5 feet by 2 feet, so the total table area will be 5 feet by 4 feet, or 20 square feet. Multiply 20 by 125, and you get 2500 CFM.

You can run the fan(s) several ways, for example, you can use one 2500 CFM fan or two 1250 CFM fans, or three 850 CFM fans.

With a hood of this size, you might want to consider two or more fans, just so that if one or more workstations are not being used, you can essentially "turn off" one entire section of the hood and not have to worry about exhausting 2500 CFM of air for just a couple of torches.

You could use a variable speed motor control, but I don't recommend them for use with a multi station vent hood arrangement, only for one fan running a multi hood arrangement, similar to what I have at MAGiC.

MikeAurelius

2006-01-09, 12:55pm

It's gotta be ducted outside - this is not an option - its a gotta...HOWEVER, how you do it is another issue. You've got a lot of flexibility in your layout.

I'd use the one window as your source of fresh air and the door to the outside as your exhaust duct.

Here's what I'd do: see if you can get a "blank" door that is the exact same size as the door that is currently in the wall. Take the new door and cut a duct hole in it where it is best - it can be at the top or bottom, no matter, however, you will be running duct through the hole, so be sure that it does not conflict with anything else.

On the inside of the back door, attach the duct with "super oversize" "hose" clamps - I've seen them with diameters up to 12" - they aren't cheap, but they will clamp the duct in place for uses such as this.

On the outside of the door, mount a 90 degree bend facing away from the house and down at about a 45 degree angle.

When you are torching, mount the duct to the door and open the window for fresh air.

When you are done torching, dismount the duct and close the window.

This is one of the very few installations that I'd use the semi-flex ducting - don't use the high flex plastic wall, but the metallaic semi-flex duct, and then only a short run of it to act as a transition between the rigid and the door for ease of removal.

Keep the old door in the basement or someplace safe, so that when it comes time to leave your house (sell it), you can put the old one back in and no one will know the difference.

Solana

2006-01-09, 3:01pm

Heather/Ericaceae

2006-01-09, 3:17pm

Mike - would you still be able to open the door when the duct is connected? from my reading, I don't think you could, unless the duct was really flexible, OR - unless you cut it into a split door thingy (since you'd be cutting up the door for the duct anyway) and had the duct in the upper part. You'd still want to keep it closed while torching, (otherwise you'd just be letting the bad air right back in), but it would be more convenient if you needed to duck into the back yard right after torching and didn't want to disconnect right away.

http://www.lampworketc.com/forums/uploadedimages.php?viewid=13234
Just a thought - good luck with your design! -Heather

lenora

2006-01-09, 3:31pm

Hmmmm....use the door for the exhaust duct? Interesting! I guess my questions related to this suggestion is what would a set up like that look like? Is it really as simple as "dismounting" the duct when I'm done torching? It seems like it would be a lot of work. We use that door a lot (it's our back door), so it'd be a pain to have to keep mounting and unmounting ductwork and such. Does anyone else use a system like this?

I use this kind of setup, but I am ducting out a window, not a door. It works great for me. The flexible duct is attached to thick cardboard that fits the window opening. It only takes me a few seconds to open the window and place the "base" in the window. I then run a second duct from a window on the other side of the room directly into my torch area for fresh air. This way, the air temp doesn't affect my room temp. I know flexible duct work isn't the best, but it is the only way I could do this without drilling through the wall, although I still may do that for exhaust. When I'm done, it just takes a few seconds to dismantle it all and go outside and turn off my propane. It's really not a big deal. Here are a few pictures that I hope kind of give you an idea of what I'm talking about.
7066
Here is the duct work attached to the left side of the hood.
6590
It vents out this window. I don't have the fresh air duct hooked up in this picture.

MikeAurelius

2006-01-09, 3:47pm

Yes, the door CAN work - you would not be able to use it while the system is on (of course), which is why I suggested the dismount arrangement, but the split door is an option too, however, the split would have to be weather stripped to prevent backflow of contaminated air.

You can run a long duct to the window, however, you will probably NOT be able to use your current fan - they are not designed for long run ducts. Ducting should always be smooth-sided (usually galvanized metal). NEVER use flex ducting, especially the kind where you can feel ribs (as shown in the picture above). This type of flex was not designed for the type of high velocity air movement we require and seriously affects the free flow movement of air by creating turbulence in the airstream.

Lenora - it's a nice set up, BUT. The flex duct and the bends that show in the picture are reducing your air flow by better than 50%. If you have a 350 CFM fan (for example), I'd bet good money you are only exhausting about 175 CFM of air.

Ducting MUST be smooth (non-ribbed, non-flex), and run as straight and as level as possible.

Dale M.

2006-01-09, 5:39pm

Solana

2006-01-09, 5:46pm

Thanks for everyone's input so far! I truly appreciate it! :)

I was just outside talking with my neighbor and he suggested I hang my fan over my workarea and use some baffles (so I don't need a fan with such a high CFM) and use smooth, metal ductwork from the top of the range to the edge of the door. He then suggested I take a piece of the flexible ducting and attach it to the metal duct and run it out the door.

Doing this would cut down on the amount of ribs/friction in the ducting and would keep me from having to buy a new door or poke a hole in the wall.

If you guys need a picture to better illustrate this...let me know.

Mike - Do you think running metal ductwork from the hood to the door would be sufficient?

Thanks again guys!

lenora

2006-01-09, 5:47pm

Lenora - it's a nice set up, BUT. The flex duct and the bends that show in the picture are reducing your air flow by better than 50%. If you have a 350 CFM fan (for example), I'd bet good money you are only exhausting about 175 CFM of air.

Thanks Mike! That picture is of the ducting when it is NOT in use. It is a pretty straight shot to the window when it is hooked up correctly, but it is still the flexible ducting. I just don't want to cut a hole in the wall. It is a 650 CFM fan.

Solana

2006-01-09, 6:01pm

Lenorasdesigns - I really like your set up too! I'm eyeing one of the 700 CFM fans on ebay right now, but at $250, I may have to wait a little bit. *gulp* I know the $30 exhaust fans at Home Depot won't do that much, but I'm worried that getting a 600-700 CFM fan may be overkill. That's moving a TON of air...I don't get how the flame can stay put with that much air be removed just above it.

firefreak

2006-01-09, 10:48pm

What about going thru the wall right above the door? There should be a space of at least 4-6 inches above the door header. a flat 4x12 or 6x10 piece of duct work with an outside cover should give the required flow. Don't cut the header, but you can move the small blocks in between the header and the top plate to the outside of the duct to carry the roof load. With no ill effect. ( I worked as a Carpenter for several years before I became a Firefighter) If the space is too small you will have to go with the other options.

Studio D

2006-01-09, 10:50pm

Have you thought about running your ductwork out a hole above your door with a louver on the outside so you could keep it permanently attached and it wouldn't interfere with your door? Deb

Solana

2006-01-10, 6:52am

Bryan/Deb - Thanks for your suggestions! I'm not at home right now, so I'm not exactly sure how much room I have between the top of the door and the ceiling. Our garage is totally sheetrocked and "finished" (including the ceiling), so there may not be too much room above the door. I'll check when I get home.

I don't have an issue cutting a hole in the wall, but I'd rather do that as a last resort since I have no idea how to do that. Plus, we have siding, and I wouldn't even know what to do to cut through that as well.

MikeAurelius

2006-01-10, 7:53am

Karla - you can't just dump it out an open door - there won't be anything to stop it from returning back into the garage. It has to pass through some type of partition that is relatively air tight and at least 10 linear feet from the fresh air intake.

Solana

2006-01-10, 9:06am

How locked in are you to having bench where it is.... What is chance of moving it to corner by window.... That way ANY door coud be a make up air souce and you could just vent out through window....

Dale
Hi Dale! I missed your post! I'm sorry! To answer your question...I'm kind of partial to the corner I'm in since there's electrical outlets, and lighting already in place. If I move corners, I'll have to run extension cords from the corner where my studio is currently located and install some sort of lighting. The extension cords aren't a big deal, but I'd rather not run a power strip on an extension cord to power my oxycon, kiln, hot plate and range hood. :)

I'd like to vent out the window...I just don't know if it'll do the job or not.

Do you think getting a 700 CFM hood and usings flexible ductwork from the hood across the ceiling to the window will do the job? Is that too far of a distance to vent the air? Will the rough inside of the flexible ductwork cause lots of problems with a 700 CFM hood? So many questions! :)

MikeAurelius

2006-01-10, 9:53am

Just don't use flexible ducting - use plain straight smooth galvanize metal ducting.

Dale M.

2006-01-10, 5:27pm

My thoughts are if you go through door its going to be a pain but workable. IF you use a split door, its going to be a head killer...

Only other solution is to just punch through wall beside bench ad be done with it... OR if you don't want to punch through wall, run rectangular smooth wall metal duct across ceiling to window and dump out window. BUT you must calculate size, distance and turns in duct to get to window and use fan with enough CFM (velocity) to move required volume of air...

Dale

MikeAurelius

2006-01-11, 5:30am

I don't recommend the use of rectangular ducting. You may get a larger cross-section, but it is very difficult to "plumb" and you cannot change sizes or shapes at any point in the duct run. Stick with round ducting, it's easier to "plumb" and easier to manipulate.

Solana

2006-01-11, 6:37am

Thanks guys! I think I'll try the flex ducting first. I want to get one of the 700 CFM hoods on ebay, but I need to wait for a little more funding. :) I think with the power of that hood, the distance from my workarea to the window, the friction caused by the ducting and the turns to get the ducting to the window (once all factored in) will give me about 400 CFM. I think that's pretty good for what I need. There's already a good flow through the garage when I open the garage door and the back door, so I think I'll be pretty safe.

What do you guys think?

MikeAurelius

2006-01-11, 7:31am

:rolleyes:

No, flex ducting is a very BAD idea. Don't try to overcome the friction loss with a bigger fan, it still won't work.

Do it right the first time and you won't have to do it over when the fan burns out, which it will.

Putting 50% back pressure on a fan motor is a Very Bad Idea. Especially on kitchen fans which are not designed for high static pressures!!!!!!!

Please, do it right the first time. Don't use flexible ducting!

Kalera

2006-01-11, 9:37am

Are the deck stairs enclosed? I'm wondering why the deck stairs prevent you from venting straight out... a low-profile vent shouldn't interfere with the stairs at all,a nd that would save you a lot of hassle.

Solana

2006-01-11, 11:38am

MikeAurelius

2006-01-11, 11:59am

Round smooth sided galvanized metal ducting is available at all home improvement stores. It usually comes in 4 foot sections. It comes in 3", 4", 5", 6", 7", 8", 10", and 12" diameters.

It is usually found in the heating/cooling aisle of most home improvement stores such as Lowes or Home Depot.

Solana

2006-01-11, 1:24pm

Dale M.

2006-01-11, 9:57pm

Mike - Sorry if I seem to be going in circles with the types of ducting. Dale suggested the rectangular metal ducting, and you suggested round ducting. The only round ducting I'm familiar with is the flexible ducting. Are you referring to PVC ducting or something like that? This whole thing is confusing. :(

Kalera - The stairs to the deck are open but they run against the wall right where I'd need to vent the air. Plus, punching a hole through the wall is a last resort since I don't have the money nor expertise to take on such a challenge. However...you mentioned a low profile vent. Would that be something like an exhaust fan...similar to what you'd find in a bathroom? If so...I may be able to get something like that to work around the stairs. I would just need to figure out how to install it through the wall.

My ideas of using rectangular duct to go from bench area to window was to keep profile of duct from extending too far down from ceiling into garage "space". Yes there is more complications in "plumbing" duct around corners and bends but with your self imposed restrictions everything you are trying to do going to complicate your installation because of your unwillingness to make certain compromises... Like moving bench to under window, it would sweep away most issues we have been discussing here if you were willing to move it.

Dale

Solana

2006-01-12, 2:23pm

Yes there is more complications in "plumbing" duct around corners and bends but with your self imposed restrictions everything you are trying to do going to complicate your installation because of your unwillingness to make certain compromises... Like moving bench to under window, it would sweep away most issues we have been discussing here if you were willing to move it.

Dale
It's not that I'm not willing to do certain things...it's what I am capable of doing and not capable of doing due to things that are out of my control.

I can't move my bench under the window because that is where my husband parks his car. I can't move my bench to the opposite corner because there are NO outlets or lighting in that corner. With that said...I don't feel comfortable having my oxycon, kiln, hotplate and the necessary lighting all plugged into a powerstrip that's connected to an extension cord from across the garage.

The only thing I'm unwilling to do is to punch a hole in my garage wall. I'm not a carpenter and I don't have the money to pay a contractor to do it.

That's why I wanted everyone's input...to see if there was an easy solution that I was overlooking. I'm not a ventilation expert so I wasn't sure of the best way to handle this challenge.

I truly appreciate what everyone has said and have a couple of ideas! Thanks all!

Karla

brimmy

2006-01-12, 4:00pm

I don't know if it will work in this case, but my friend has a wood studio in his garage. What he did is create a large wooden box suspended from the ceiling in the centre of the room. On all four sides, instead of solid walls, he inserted high grade furnace filters. Inside the box is an old vacuum cleaner plugged in and permanently turned on. The vacuum is plugged into an outlet that can be disconnected (therefor turning off the vacuum) by flipping a regular lightswitch.

He later upgraded his setup to get rid of varnish fumes. What he did is seal the intake to a length of large flexible duct which came to an opening on the bottom of the box. He then added a quick release connection to be able to add another length of flexible duct which was suspended by rope to the roof across the room to where he usually worked with the varnish (this was movable so he could work elsewhere). The intake to the vacuum would then be centralized around what he needed venting.

For outtake, he did the same and sealed it to a flexible duct which came out the bottom of the box and another quick release connection. He then had TWO flexible ducts which could connect to that hole. One was short and looped directly back into the box. The other was longer and went across the roof and out a vent above his garage door. [edit : Instead of punching a hole in your garage wall, you could instead just open the door a crack and shove the flexible duct out when you need it.]

Basically, if he wanted to work with wood and get all the dust and other particles out of the air, he would disconnect the long intake and connect the short piece to the outtake. This would bring in air and filter it through the furnace filters of the box much like the original design.

If he wanted to vent fumes, he would connect the long intake duct and move it where needed and then connect the long outtake and vent it outside into the alley.

I know this sounds complicated, but it is really quite simple. When I get a chance, I will sketch out the plans for this system. It is also quite inexpensive. All you need is some wood, four furnace filters, two connections, a bunch of flexible duct and a strong second hand vacuum.

Solana

2006-01-12, 4:08pm

Thanks for the suggestion, brimmy! I'm definitely interested in learning more! :)

MikeAurelius

2006-01-12, 5:18pm

Brimmy and Karla -- there is a **HUGE** difference between removing combustion byproducts and removing sawdust plus varnish odors.

No one, I repeat NO ONE recommends the use of a vacuum, industrial, commercial, shop, or other to properly ventilate any type of installation that uses an open flame.

Please people, let's use some common sense here! You are comparing apples to oranges!

brimmy

2006-01-12, 10:26pm

It was a suggestion not a hard fast, "do this" comment. I stated very clearly in the post what he used it for and how he adapted it. It is quite possible to adapt it further, which I leave up to the person installing it.

Besides, if you're going to criticize other people's help, please explain why you think it is a bad idea rather than just hashing down on it.

MikeAurelius

2006-01-13, 5:34am

brimmy - it's not an exhaust system. It is a device or setup for removing dust and VOC fumes.

There are many thousands of words that have been written (mostly by me) and posted on a variety of boards -- and nowhere is it advocated to use a vacuum cleaner to run your exhaust system. Vacuums are designed with small diameter high CFM suction fans to enable them to pick up and transfer dust and particulates. You won't see duct diameters exceeding 2". These vacuums will not work on large diameter ducting, the loss of CFM will kill the system.

Exhaust systems, especially those designed for torch working applications require lower CFM large diameter fans so that large amounts of air can be moved quietly and efficiently. These system are not concerned with moving particulates but combustion byproducts.

These are the obvious reasons, there are other more technical issues as well.

Solana

2006-01-13, 7:08am

I just wanted to repeat that I appreciate everyone's suggestions and thoughts! You all have been a wonderful help! :)

Mike/Dale - I appreciate your patience with me and with the others who have posted in this thread. However, I wanted to remind you both that we're not ventilation experts. :) A lot of us don't know the nuances of how exhaust systems should work. What may seem like common sense and is obvious to you guys, may not be for others....like me! If we were all educated with this stuff....then there wouldn't be so many ventilation threads on LE or WC....seeking your great wisdom! :)

Thanks again!

MikeAurelius

2006-01-13, 8:13am

Karla - it IS sometimes difficult to be patient especially when the same thing has been said over and over again...

but I try ;)

Dale M.

2006-01-13, 9:12am

aI just wanted to repeat that I appreciate everyone's suggestions and thoughts! You all have been a wonderful help! :)

Mike/Dale - I appreciate your patience with me and with the others who have posted in this thread. However, I wanted to remind you both that we're not ventilation experts. :) A lot of us don't know the nuances of how exhaust systems should work. What may seem like common sense and is obvious to you guys, may not be for others....like me! If we were all educated with this stuff....then there wouldn't be so many ventilation threads on LE or WC....seeking your great wisdom! :)

Thanks again!

Some time we say things over and over and over, and people don't listen, don't think, don't care or refuse to recognize we are really trying to help and keep them safe....

But we do believe we are doing right thing....

Dale

MikeAurelius

2006-01-13, 9:34am

But we do believe we are doing right thing....

or we wouldn't bother...

Dale M.

2006-01-13, 10:01am

or we wouldn't bother...

Yah!

Dale