Pole Barn Exhaust Fan

[89Vette]

I am in Michigan and have a natural gas heated 30x48 pole barn with cement floor and insulated walls and ceiling with metal clad interior (ribbed just like the exterior). I want to put in an exhaust fan so I can weld on a project car in the Winter. I looked on-line but wondered what others have done and how big a fan should I put in? Is a 2 or 3-speeed worth the extra money? I won't be out there all day, I am lucky to get a few hours at a time. I plan on opening a window to allow air in when it is running in the Winter. How high should it be off the ground? Thanks.

 

[188slo50]

I'm interested also for my 30x40 pole barn.

 

[rond]

I had a 24 by 40 insulated pole barn that I have recently replaced with a 32 by 32 stick build garage. My choice was a 24 inch J and D fan http://www.greenhousemegastore.com/product/shutter-fan/hobby-greenhouse-equipment , the VES24. By all means, I would strongly suggest using a variable speed controller, particularly if you are planning to use the fan in the winter. I have mine for painting, but I learned the hard way that you cannot mount the exhaust fan in the peak and expect it to do any good. Mine is about head high, with a filtered inlet plenum that runs from 6 inches above the floor, to about 4 ft high. I would suggest mounting the fan between waist and shoulder high. As a double check, why don't you lay down some wire, then see how high above the floor the center of the smoke is. That is the height you want to mount your fan.

 

[89Vette]

Thanks Rond, that height makes sense.

I have read that the exhaust should not face prevailing winds which puts me in a bind. I am about 2 miles from Lake Michigan and there is always a breeze up to a gale from the West or Northwest usually. My barn goes N-S which I am thinking rules out the North & West sides. The East side is where the garage doors are which limits wall space, the South side has nothing. Do they make window mount units? I have a window in the NE corner. The stall the car is in is the middle one, a ways away from the window, how close to the area where I weld should the exhaust fan be? The window I can open for the air intake is in the NW corner so I am thinking it might not **** out the fumes anyway with the windows so close. Even the South side is a ways away from where I weld.

 

[89Vette]

Exhaust fan for pole barn

I asked this in the General section, maybe I can get more help here. I am in Michigan and have a natural gas heated 30x48 pole barn with cement floor and insulated walls and ceiling with metal clad interior (ribbed just like the exterior). I want to put in an exhaust fan so I can weld on a project car in the Winter. I looked on-line but wondered what others have done and how big a fan should I put in? Is a 2 or 3-speeed worth the extra money? I won't be out there all day, I am lucky to get a few hours at a time. I plan on opening a window to allow air in when it is running in the Winter.

I have read that the exhaust should not face prevailing winds which puts me in a bind. I am about 2 miles from Lake Michigan and there is always a breeze up to a gale from the West or Northwest usually. My barn goes N-S which I am thinking rules out the North & West sides. The East side is where the garage doors are which limits wall space, the South side has nothing. Do they make window mount units? I have a window in the NE corner. The stall the car is in is the middle one, a ways away from the window, how close to the area where I weld should the exhaust fan be? The window I can open for the air intake is in the NW corner so I am thinking it might not **** out the fumes anyway with the windows so close. Even the South side is a ways away from where I weld.

Thanks.

 

[Highbeam]

Re: Exhaust fan for pole barn

If the fumes get too bad in there, doubt they will, then open a window/door. Lucky to get a few hours, a huge building, only you welding, don't worry about it. Dilution is the solution to this level of pollution.

Your farts will smell worse than the welding fumes.

 

[pseudorealityx]

Re: Exhaust fan for pole barn

For personal use, a general "relatively low" airflow exhaust isn't a bad idea. Run it as needed on a timer or wall switch. Something between 500-1000 cfm. But that would cool down your space relatively quickly in the winter.

Because you're working on a car, and you'll presumably be moving all over and doing welding in various locations, a specific fan for exhaust isn't really practical. If you were doing something small, or had a dedicated small area that you always welded in, you could look at something a bit more specific, but for you, a general exhaust fan is your best bet if you want to remove said fumes.

 

[89Vette]

Re: Exhaust fan for pole barn

Thanks!

 

[rond]

They make commercial deflectors for chicken houses and greenhouses to deflect the air down as it exits the building. I believe that J and D fans show them on their website. A simple deflector would not be hard to make out of plywood. Keep in mind that the closer you are to the fan, the more effective you will be at pulling the fumes out. Another reason for wanting to have a variable speed controller like this one http://www.greenhousemegastore.com/product/variable-speed-control-10amp/

 

[404]

If the goal is to weld inside a heated building and not inhale smoke maybe this would interest you.

http://store.cyberweld.com/3mspad91wadf3.html

Yes it is expensive but the building stays warm and the helmet has a visor that goes up so it can be used for grinding etc.
Keep it on all the time, be fully protected.

Regards,
404

 

[sands35]

Pick up a used kitchen exhaust hood or blower. Typically either 600 CFM or 1200. Some can run on multiple speeds with a multi-way switch. If it's good enough to remove cooking odors, it's moving enough air to evacuate welding smoke.

The nice thing about a kitchen hood is that you will typically get some lights as well.

I did just that for a sanding / painting / welding workspace.

 

[Bill's Auto Works]

I bought my exhaust fan for my booth from Grainger. I mounted it 6 inches from the floor, it has flaps on the outside that open when the fan is on, I also use the variable spped controller. I built a wooden box around the inside, with a hinged door, insulated it & put the metal siding on it so it matches the rest of the booth walls. Even with the intake vents at the other end, the fan will **** the walk in door closed if you turn it up all the way! I never really thought about a fan for mig welding & I have done many large jobs in the last 20 years. I guess being a painter/customizer/ restorer I am used to being in some type of smoke/fumes most of the time LOL

 

[89Vette]

Wow, that is a good chunk of change! Out of my range right now. Thanks, I will check Grainger too.

 

[SALIV8]

89vette- grainier is typically waaaaay overpriced also check out McMaster.com and once you find the unit you want, I'd search for the best pricing. Amazon, alibaba, etc.

For decent air removal you'll need to figure out an intake also(or just crack your door?). Not sure what's gonna be the best idea in s/w Michigan's snow belt.

I'm in Clyde township so we're neighbors. Good luck on whatever you decide.

 

[SALIV8]

If it were me, I'd try a couple ideas first, that are super cheap. What about a typical floor box fan (what are they like 24" by 24"?) that I'd stick under a slightly opened overhead door and make a plywood, maybe veneered with foam for insulation, cut out for the sides to seal up decent. Crack another door behind me for flow.

Or a similar idea, place the fan on a table near the service door and place the insulated plywood above and below the fan to seal as best possible and setup your welding station near that. Then crack a different door behind you.

That is if this will not be constant welding.

Just some cheap ideas to get a gauge on heights and flows needed.

 

[Jbullfrog]

Have you looked at a portable fume extractor? They have an arm with an inlet pipe and a length of tubing to route it out of the building.

 

[89Vette]

Cheaper ways are better!
Right now I don't expect much welding on my welding table, most of it is the car body so it will be over a large area in the middle of the pole barn. I actually thought about using a box fan and then making a panel out of thick insulating styrofoam that would fit under the overhead door down to the floor when I raise it to fix the box fan underneath. Plus make a "C" channel on top of the panel the door bottom would go into to better seal it. But the door peels away at the top and doesn't seal so there would still be a big hole at the top not sealed.

 

[89Vette]

Along the lines of finding a cheap way to do this, I think I will make a panel out of 2" foam that fits tightly in the entry doorway and then cut a hole for a box fan. If it doesn't do a good enough job then I guess I will have to cut a hole in the wall for a real exhaust fan next summer, something I have been trying to avoid. Hopefully it works good enough.