open window or makeup air vent?

ShellyJo1969 · #1 2010-06-16, 2:46am

DO you open a window for your makeup air supply OR do you have a special vent by your work area?

Which one of these two options will work better in winter time????

I can't decide because essentially they will both be open holes in the wall right?

Helpful input is greatly appreciated.
Thanks!
Michele

HerbalBurn · #2 2010-06-16, 3:16am

i'll worry about it when winter comes around.. for now, i'll blow glass in my driveway.

HerbalBurn · #3 2010-06-16, 3:19am

if you dont have an air current, then an open door would only potentially blow air into your studio.. without any means of taking it out.. if its not raining, to cut down on fumes, run your kiln outside if you can.. otherwise, get some of that(dryer tubing) and run it outside over your torch.. and some way to hook a devise to pull air out of the studio space through the tubing.. and a fan to bring air in to circulate. in the winter time.. i suggest you insulate your venting area, and figure a way to bring fresh air in...

ShellyJo1969 · #4 2010-06-16, 5:25am

I'm already cool with venting my contaminated air to the outside (or rather I will be once I get all set up) , I was just wondering if I must open a window or have a makeup air vent close to me in a large open area???

GlassGalore · #5 2010-06-16, 5:43am

Yes, you must have as much fresh air coming in as you have being pulled out through the ventilation system. I cut a fresh air intake right into my workbench, which would ensure that the cold air coming in was staying under my hood area and being vented right back out in those colder months.

Even though I calculated the intake capacity to be = the size of the vented air going out, I found that I was still drawing a vacuum in the basement (where I torch). So it ends up that I use both. The in-bench makeup air AND a partly open window at the other end of the basement, allowing more fresh air in that is not right on top of me.

Dasi · #6 2010-06-16, 5:46am

You need makeup air coming in that is not near your exhaust system. You want clean air coming in and a good exhaust system taking it out.

NMLinda · #7 2010-06-20, 5:17am

The opening of your make-up air source should be no closer than 10' from your ventilation's exhaust point to the outside so that you don't accidentally pull bad stuff back into your work space. The opening of your make-up air source should be larger than the diameter of your vent ducting, the larger the better. Don't rely on the available air in the building, no matter how large it is, or any 'leaks' it might have.

If you have a window that's at least 10' away from your exhaust vent, and if the window isn't particularly close to where you're sitting, try that. As I recall, your building isn't insulated, so you'll likely be working with a small heater in your work area, anyway. If the window is far enough away, the fresh air will likely be warmed by the heater before it reaches you. You may find that works well enough.

Linda

Dale M. · #8 2010-06-20, 6:51am

Guess its time to redirect to this thread and basics....

http://www.artglassanswers.com/forum...php?f=22&t=150

http://www.artglassanswers.com/forum...php?f=12&t=273

Dale

NMLinda · #9 2010-06-20, 9:26am

Michele - Dale's links are great info, and should answer many of your questions. Recommended reading.....

Linda

HerbalBurn · #10 2010-06-20, 9:10pm

Good info! i'll try and incorporate some of those ideas when i need to move in the house when winter sets in..

NMLinda · #11 2010-06-21, 4:21am

Quote:

Originally Posted by HerbalBurn

Good info! i'll try and incorporate some of those ideas when i need to move in the house when winter sets in..

Glad you found it helpful. I was concerned about your earlier post about just hooking up dry vent hosing over the torch. The stuff is crap from a loss perspective (as is flexible ducting, by the way), and, as Dale's posts in the links he provided indicate, you need a way to funnel, capture and collect the fumes above the torch. You also need to match the fan size so that you get enough draw. In designing a safe system (which can be done reasonably inexpensively, by the way), static pressures of your vent ducting need to be considered. Adequte ventilation takes a little thought. In addition to Dale's excellent posts on Art Glass Answers (great safety resource on many topics), I also highly recommend the ventilation primer info at

http://mikeaurelius.wordpress.com/ventilation-primer/

Folks have made themselves ill, especially working indoors, by not carefully considering ventilation: we want you to be safe, too!!

Linda

RSimmons · #12 2010-06-21, 5:49am

Dryer vent duct is not big enough to use for any part of your ventilation system.

Robert

cheng076 · #13 2010-06-21, 10:24am

Simple answer to your question and incorporates a lot of Dale's info as well as that posted is this;

Makeup air must at least equal exhaust air or a vacumn will result in the work space. If your makeup air supply is bigger than your exhaust the velocity of the makeup air from the outside to the vent hood will be slower resulting in less noise and irratating drafts on your body (head and neck) in an open window/door style setup. If you go with a ducted system then I highly recommend a larger duct size for the makeup air than used in the exhaust side of the system. Don't forget to take into account the system losses incurred by the extra ducting in your calculations.

If the makeup air comes from an open window or door it has to travel across the workspace and thus mixes with the workspace air and reduces the temperature, sometimes significantly. If the makeup air is ducted to the workbench area such as under the bench or through bench openings then the colder makeup air does not mix with room air before it sweeps up the harmful products of torching and is exhausted outside so the room stays warmer. There is, of course, some room air vented but this room air is replaced through normal and inevitable system leaks.

It sounds like you have done due dilligence in setting up your studio and are simply looking for the best solution to save energy and conserve the workspace temperatures. A ducted system will do that but needs be balanced against the extra cost and added contruction concerns and how severe the winter temps are in your area.

My system makeup comes from behind me and in winter can be irratating on my nech and bald head so I wear an insulated hoody.

Hope this and the other info helps, PJ

RSimmons · #14 2010-06-22, 6:14am

My make up air comes in under my work bench and through the table top. The exhaust duct is 8 inches and powered by a squirrel cage fan. The make up air comes in through an in-line fan (the Glasscraft fan that came with the hood) in a 10 inch duct. My room stays pretty much the temp I have the house set for and the temp in the duct is pretty close to whatever it is outdoors. If it's really nice out I can leave off the powered makeup and open the windows on the far side of the shop. It all helps out with the HVAC bills.

Robert

Copperrein · #15 2010-06-22, 6:39am

I ran across an old turbine fan I have Sunday. I used it for spray painting in a booth. It's kind of scary when powered on but it takes dryer vent hose....tho this is no normal fan...it would remove hands if I let it.

The range-hood works great but I really really want to use the baby turbine so I can get that awesome 40 degree bend in my flame due to suction. Moar Poweh!

The problem I have is with the heat. I'm a baby during the summer and with the all the crap I have going in the *studio* outside ambient is 86f and the work area feels like 102f (probably more like 89f...but I hate hot weather and sweating down my rear-end crevices and such)

If I toss an AC pointed at me I worry about shattering glass due to difference in temp or some such...any experiences, suggestions, chastise-ations? MY ideal operating temp is 65f-68f Hahahaha

Dale M. · #16 2010-06-22, 8:04am

The difference from the air temperature in room from AC is not going to have much effect on glass..... Its the going from "room temperature" to 3000° f. that shatters glass....

Dale

ShellyJo1969 · #17 2010-06-23, 3:21am

Ok, so I know that you must have as much "make up fresh air" as you do "polluted air" being sucked out of the building. Now, I can open a window that's 40ft away from me on an adjacent wall, OR I could try to convince hubby to put another hole in the wall next to my bench for make up air.

The temps in winter where I live down south can get down in the teens, actually they can get to minus a few degrees on occasion, but I doubt I'll be working those days...who knows though. I like to plan for all possibilities.

In any case, I'm trying to figure out how ducting the fresh air up through the table top would help? I mean the point of providing the fresh air is to make certain that you have enough fresh clean air to breathe right? Because the suction is taking away your bad fumes along with your rooms air supply and you must replace that with fresh air? Yes? So if you duct fresh air straight through your table top that air gets sucked straight through and out the vent hood and you don't get to breathe any of it! Or am I missing the point?

Since my workbench is a metal table, I don't think I can swing putting big duct holes into my bench top. So what's My best option? Just open the window OR make a vent hole next to or under my work bench? If I put a hole in the wall next to my work bench won't that be just as cold or colder in winter than opening a window???

I'm obviously once again in serious need of an informed, experienced opinion(s).

Thank you all now, Please Help!

Michele

Dale M. · #18 2010-06-23, 7:46am

Just by the nature of air flow (path of least resistance) you will have plenty of fresh air flowing around your head to insure you are breathing fresh air... The MAIN thing is that you have a path for contaminated air to escape.... Since nature abhors a vacuum, it will take care of the rest to replace contaminated air by forcing air in to low pressure area (under hood) any way it can and if a large percentage comes up through bench that is ok. The rest WILL come from room but not enough for full replacement of heated or cooled air every few minutes....

IF you duct makeup air in under bench and feel it does not cause enough makeup air flowing over your head and shoulders simple restrict bench duct some and open door or window....

Sort of think it as the heating and cooling vents in your car, you have choices of heated or or cooled or directly on your face or on your feet or both and some other choices.....

If you do not want to cut metal top of bench, move it out from wall and bring up portion of air between bench and wall.... The rest can come over your shoulders...

Dale

cheng076 · #19 2010-06-23, 10:51am

Your bench vent hood is a little like your vacumn cleaner floor attachment. When you stick it down into a pile of dust you see all the dust directly under the opening get rapidly sucked up AND you see a diminishing by distance flow being swept in from the sides - like if you had makeup from across the room. If you had paper bits or whatever laying on top of a screen like a furnace floor opening you still see all the paper under the opening get sucked up quickly but very much less suction from the sides because the air stream or 'makeup' air is comming from a 'point' source, the duct under the screen.

You seem to be worried that you might deplete the torching area of air required to breath. It is not a problem. Firstly the size of the room you describe would supply you enough air to breath for days even if completely air tight. And there is always some 'leakage' from under the bench or out of the duct that helps keep the room air fresh; no system is perfect. What you are trying to achieve is that all the contaminated air under the hood and/or near your torch is sucked up and disposed of while bringing into the 'system' enough clean air to replenish the air sucked up and exhausted. A ducted system brings that air in without mixing with room air so the room air is unchanged while a window system mixes all the air in the room before some of it is sucked up and exhausted.

While having an opening in the wall directly under your bench would be ideal, you only need to ensure that ducted makeup air is brought in at least 10 feet from where the bad air is exhausted... so maybe a minimum of 10 or 12 feet of ducting.

I posted some pics of a test setup illustrating some of this a few months ago that might help you visualize what we are talking about. Dale and others have exhaustive posts on ventilation here that will reassure and guide you.

You do not need to put holes in your bench. Having the duct end under the bench and allowing the air to flow up and around the bench edges will be sufficient. As Dale said a flow from under and up the back works well.

PJH

ShellyJo1969 · #20 2010-06-24, 2:49am

ok thanks guys. My problem is that my vent hood is rather low and if I want the fresh air vent under my table, I'd nearly have to put the fresh air vent hole by my feet and at ground level in order to get it 10 ft away from the bad air exhaust outside, and also it would be sitting right next to my propane tanks also. I don't know if I can or should do that? It'd be bad to suck in propane fumes and bad exhaust fumes into what is supposed to be my fresh air supply!

If I cannot put in a fresh air vent, which is obviously the ideal, an open window should suffice right? I"m pretty sure Dale says that is so on art glass answers!
(Any time I speak to my hubby about setting up my work area and we disagree about something I always come back with "well Dale says so, or That's not what Dale or Bill says!) Lol!

michele

NMLinda · #21 2010-06-24, 5:52am

You may be thinking about the option of under-the-bench make-up air too literally. The building you're in is quite large, as I recall. You don't have to make an opening for fresh air directly under your work table if that's not the best place. I believe you have room to cut an opening for make up air a safe distance away from your vent exhaust/propane tank. You can then run vent ducting over to your work bench. If memory serves, I think the window you mentioned is fairly large, so it should also be a good make-up air source.

Linda

Linda

ShellyJo1969 · #22 2010-06-26, 2:10am

Well I know what my husband will say, "What's the point of putting another hole in the wall if you can just open a window?" And to be honest, I can't really argue with that logic! Dang it!

I can totally see how putting in a duct might help with room temperatures some, but other than that an open window seems like the same thing as an open duct.

cheng076 · #23 2010-07-01, 10:20am

ShellyJo,
You are correct that an open window is technically the same as an open duct (for this discussion). The difference is that makeup air from a distant window mixes with room air on its way to your vent hood thus lowering the total room air temp before it is exhausted out by your hood. An open duct that brings the makeup air to the bench does not allow that air to mix with room air so it does not cool the room. The ducted MU air then sweeps up around your bench edges collecting the bad stuff and is exhausted out before cooling the room.
HTH, PJH

ShellyJo1969 · #24 2010-07-09, 9:49pm

That makes perfect sense. SO IF and that's a big IF, IF I can get hubby to put a duct in for me for this winter, WHAT SIZE duct? Or can it be like a few floor register sizes or what?

Great, a whole new can of worms!

Dale M. · #25 2010-07-10, 7:08am

Any make up air duct work and registers need to be equal to or larger than exhaust duct (is square inches of area)...

Dale