Basement exhaust blower - Woodworking Talk

Ephriam · 03-27-2009, 12:08 PM

My basement dimensions are about 30’ X 50’ X 8’, a volume of 12,000 cf. How big a blower is needed to exhaust dust so that little gets upstairs into the house? I’m not overly concerned about personal safety because I wear a mask when I sand. It’s my wife who has COPD that I’m worried about. Windows located at one end of the basement and stairs at the other should provide enough air flow to keep the upstairs clean. Is there an advantage in installing two blowers? Advice will be greatly appreciated. Thank you.

Fred in Rhode Island

Kudzu · 03-27-2009, 09:26 PM

It's not so much clearing out the whole basement air as I think it would be catching the dust at the source.

My next question would be how is dust getting upstairs? Once you answer that seal those leaks for starters.

And by all means read Bill Pentz site on dust collectors. There is tons of information there and a good bit relates to health issues with dust.

firehawkmph · 03-28-2009, 10:09 AM

Fred,
If you try to exhaust a big volume of air out the window, you have to have makeup air to replace it. Which in the winter time, wouldn't work too well, unless you are part eskimo. You could get a couple of the hanging air filters, try to collect the dust at the source. But no matter what you do, you are still going to get some dust upstairs. You would have to have two completely independant heating systems, one for upstairs and one for the basement, seal off the basement from the upstairs, no common return airducts, etc., to try and eliminate the dust upstairs. You can minimize it though, by doing what has already been mentioned.
Mike Hawkins

woodnthings · 03-28-2009, 11:05 AM

First, collect the Dust at the source using shop vacs and or a 1 Micron dust filter on the 1 1/2 Hp collector. Shop vacs, can be purchased on sale for $ 60 or so at Sears, the Depot, etc. and provide a lot of high velocity suction at the nozzle. You can't have too many or too much DC. I also liked this concept:
http://clearvuecyclones.com/Order_Page.htm
Next invest in a "whole room air exchanger" similiar to the Jet, Penn State, JDS, etc and run it all the time. They also have a timer for when you leave the shop. Visit this sit just as an example:
http://marleyturned.com/id164.htm Since you live in a COLD climate avoid changing out the air to the outside, unless you provide return air path, YOU WILL BE CREATING NEGATIVE PRESSURE IN ALL YOUR CHIMNEY AND VENT STACKS. DON'T DO THIS! CARBON MONOXIDE HAZARD! STAY SAFE, .......

bill
PS I have 4 shop vacs, 3 upright dust collectors and a whole room air filter in my 25 x 30 shop. and an exhaust fan in the ceiling. I don't have any vent stacks in this room..electric heat only.

rrbrown · 03-29-2009, 07:58 PM

Quote:

Originally Posted by woodnthings

PS I have 4 shop vacs, 3 upright dust collectors and a whole room air filter in my 25 x 30 shop. and an exhaust fan in the ceiling. I don't have any vent stacks in this room..electric heat only.

Is there any room left for tools?

Seriously though I was looking into the whole room air filters to get the left over dust out of the air. I agree about not wanting the negative pressure from the exhaust fan and that he should get DC, but maybe he can start with one unit and ducting to all equipment and use blastgates. Like me He may also want to look at the whole room filter systems to get the leftover dust.

woodnthings · 03-30-2009, 10:59 AM

Thanks Richard, and I know I go overboard on things, but woodworking is like riding a motorcycle. We do it for the enjoyment, knowing full well that it can be dangerous. We do everything as safely as we can and BTSH bad things still happen, usually in a laspe of thinking, IE brain fart. Sometimes BTH but have not anything to do with us, especially on a bike and less likely in the shop. Usually in the shop an accident is self inflicted. And we later say I knew that wasn't a good idea, but I didn't want to take the time to do it "safely". So, when working in the shop one sunny morning, I saw how much dust was glinting in the sunlight. It made me want to have the room air filter on any and all the time. Even with the systems I have in place, I still can improve collecting dust at the source. My overarm collector on the table saw collects so much dust it's hard to believe. The newer saws have the blade shrouded, so that works a lot better. The bandsaw is a big offender that people may not realize. I also have a 24" General dual drum dust generator...lots of fine dust comes off that unit. There was a recent post on dust masks: I need a dust mask Amazon, and Woodcraft were mentioned. The Woodcraft was battery powered. I guess the reason for all of this goes to the point: What we enjoy doing shouldn't kill us!
So, I think that all the discussions on this topic are good and increase awareness. And you know, if I hadn't read or seen something about negative pressure creating a CO hazard, I wouldn't have known about that issue, so I am happy to pass it along!

bill

rrbrown · 03-30-2009, 12:38 PM

Bill,
You are corect, I try and collect alot of the dust at the source but the bandsaw and tablesaw seem to ba a problem I have been using the TS without the blade gaurd but recently after looking at the post Let's see some damage. and reading your last comments have started reconsidering that. It seems that know matter how careful you are there's that one time you get destracted or lazy and something bad happens. As for the dust I was looking into getting or building my own overarm but maybe the blade gaurd alone would help. My shop is open and well ventelated (2 lg windows and a gargae door) so I don't have the same problems as some of the basement shops but still have alot of room for improvement.

I use two respirators (No Not at the same time) I like both types but sometimes Filters are easier to find for one then the other. They both also have different filters for dust or fumes.
http://www.homedepot.com/webapp/wcs/...ctId=100143655 and http://www.homedepot.com/webapp/wcs/...ctId=100195886.

I also recommend that if you use exotic woods you look at this post
In case anyone is interested

Ephriam · 03-30-2009, 01:40 PM

Thank you Kudzu, firehawkmph, woodenthings and rrbrown for responding. I thought I was aware of the safety issues relating to dust in the workshop but the level of concern that you’ve expressed has certainly raised mine a notch. The CO danger posed by negative pressure is something I wasn’t aware of before.

OK, it’s time to fess up. Everything I wrote above is so but I left a bit out. Go back in time to last summer when the orangeburg sewer pipe under my cellar flooor collapsed. A crew sawed a diagonal trench across the floor and installed plastic pipe which I trust will outlive me. They didn’t use a wet saw but tried to keep the dust down with spray from a hose. It helped some but I’ll never see the last of the concrete dust. Half the basement floor had been covered with asphalt tile (previous owner, forty plus years old) all of which I pried up leaving behind a pattern of cured black bonding agent in neat squares bordered by raw concrete. The other half of the floor was coated (again forty plus years ago) with paint which is now showing concrete in patches. The bottom line is I want to coat the floor with something that will keep it from flaking and I figured that whatever I use will require immediate exhaust to keep fumes from getting up into the house.

I figure that with the cellar door and the adjacent back door open, I can run the blower(s) and exhaust the fumes out the cellar windows at the other end. I would now only do this on a mild spring day. My wife would be safely stowed at my sons house until the fumes cleared.

Aside from the question of blower size, I don’t know what I can effectively use on the floor. Maybe nothing. But if I install an exhaust blower, at least I could unlimber an electric leafblower in the basement to lift the accumulated dust and hopefully move it outside (while wearing a canister mask and goggles).

I have a single stage dust collector and a JDS hanging filter unit but they’re no match for concrete dust. I wonder what that dust has done for the life expectancy of my power tools.

Thanks again for the advice and the links which I hope to check out today.

Fred from Rhode Island

rrbrown · 03-30-2009, 05:10 PM

I don't know much about basements except that I wish I had one. As for floor problems and wanting something to fix the floor ect. I would recommend Permacrete http://www.permacrete.com/ or a 2 part floor epoxy. I know the permacrete is nice can be used for leveling and filling cracks and runs about $3.75 a sqft so it can be a bit costley; however I believe it's rated at over 6000 psi. The 2 part epoxy flooring cost about $100 for a do it yourself 2 car garage. I'm sure you will need to ventilate for both but will have a good floor after it is done. If you have to ventilate open your window and I believe an entry door for cross ventiation and use a exhaust blower then tape and seal your door to the house if possible to eliminate as many fumes as possible from getting inside. I actually want to go with permacrete for my patio and shop but may have to settle for epoxy floor in the shop. Hope this helps.

Ephriam · 04-07-2009, 07:04 PM

Thanks again Richard. I'm going to focus on rigging up an exhaust blower before doing anything about the floor.

Fred from Rhode Island

DaddioDave · 04-21-2009, 08:59 PM

Hi, New to this forum. In my small 12x15 basement shop, I installed a small 300 cfm exhaust fan which vents outside. I have a variable speed controller on it. While this small fan is unable to clear the dust from my shop, it is capable of maintaining a negative pressure within the shop. This keeps any dust or fumes within the shop from escaping into the rest of the house. Of course I have to keep the shop door closed and will close off most potential air connections with the rest of the basement (overhead joist spaces). My central forced air heating/cooling system is also closed off from my shop. The small amount of air that gets sucked in from the rest of the basement/house is replenished by the normal home air leakages. I have found no adverse effect on the vent stack operation from my hot water heater (still get good exhaust and no measured CO). I put the variable speed control on the fan so I could turn it down in case I did get some effect. I also run it at a slower speed in winter to minimize the amount of cold outside air that gets sucked in. This system works really well. My wife now spray finishes the baskets she makes in my shop, since the exhaust fan will keep the smell out of the rest of the house. Of course, if I make dust in the shop, I still have to control it with my dust collector and a Jet AFS-1000 air filtration system. As I said, the exhaust fan will not control the dust, it only creates a negative pressure that confines the dust to the shop.

Ephriam · 04-22-2009, 05:20 PM

Thanks DaddioDave. Hadn't thought of a variable speed blower. My concern was to not overpower the space and a variable blower solves that problem. Now to make sure that I don't buy an underpowered unit. By the way, are you exhausting through a wall or window? My basement windows have 11" X 14" lights and I'm thinking of replacing one with galvinized sheet to fit the frame and then mount a commercial vent hood like those used for attic vents which should keep out rain, wind and critters. I think that's a neat approach but wonder if there's an easier way to go about it.

Like you I want to keep shop fumes from migrating to the upstairs quarters and that's my primary motive for installing an exhaust fan. However, after reading about the length of time that submicron dust particles can stay suspended in still air I will also run the fan for a number of hours during and after using power tools.

You and others have made me aware of potential problems of excessive underpressure in the basement. I have a CO detector upstairs and will get a second unit for the basement.

In winter I run a fairly large woodburning stove in the basement that does not have an external air supply. The heat it supplies more than makes up for the cold air it draws into the house but of course I have to run a large humidifier upstairs to keep it liveable. It keeps the floors upstairs warm which my wife loves and it lets me work in the basement in winter which I love. Anyway I think that if the exhaust fan gets too enthusiastic the stove will tell me pronto.

Thanks again for your help.

Fred in Rhode Island

DaddioDave · 04-22-2009, 06:48 PM

Hi Fred,

I find the 300 cfm exhaust fan to be more than adequate to establish the negative pressure I need. In fact, I can turn it down to a very low setting on the controller and it still keeps dust or odor from leaving the shop. I bought my variable speed fan controller here . The fan I bought has a standard 3 1/4 x 10 inch rectangular exhaust port which connects to this size duct work (also found at HD). I bought a wall vent that I put through the wall in the side of my house between two basement ceiling joists. It was fun cutting a 3 1/4 x 10 inch hole in the house. It's a brick wall on the exterior that I had to go through. I found the easiest way to accomplish this was to use a hammer drill (which I bought for this project) and drill a series of small holes around the desired opening. I could then knock the brick out with a chisel. (Sounds easier than it actually was). I mounted the exhaust fan only a few inches from the exterior wall, in between the joists. I have metal conduit running down my concrete basement shop wall to a box where I mounted the controller. Looks good and works great!

Dave

Ephriam · 04-27-2009, 07:41 PM

Hi dave,

Thanks for the links and the advice. I've been looking at Broan brand blowers but your NuTone (made by Broan?) is comparitively reasonable, particularly on Amazon. Hey, knocking a hole in a brick wall would intimidate me, it's great that you could do it.

I want to mount my blower a little ways off the window (back wall) so I would need to use some sort of ducting. I wonder if there's a coupling that transitions to round duct. Might make it easier to attach to the window. I'll check out HD. Again, thanks.

Fred

JackC · 04-29-2009, 12:51 PM

Fred,
I've yet to build it but I have a motor with a squirrel cage fan from a hot air furnace that was replaced with a new unit, got it free from Contineltal in Johnston. A simple box with furnace filters and a switch you're in business. Do a search for homemade air cleaners.

You can get the concrete ground, messy yes but you'll end up with a smooth floor. Then anyone of the garage epoxy coatings will give you a great looking floor.

btw, I'm in Warwick.

BobbyfromHouston · 04-29-2009, 01:04 PM

I would go with an ambient air cleaner as some have mentioned. Of course capture the dust at the source.... I have a 21 x 53 shop and use a couple of different methods to keep the air clean for me and my boys. 3HP dust collector for at the source pickup. I use one 3 ton shop made blower with filter to exhaust air through the ceiling and into the attic where it then goes outside. I also have about 4 blowers that are ambient air cleaners and just clean the air and exhaust it back into the shop. They are turned so that they all circulate the air in the shop in a circular motion. It prevents me from running my air conditioner alot of the time. I don't use the exhaust blower when the air conditioner is on for obvious reasons.
I have so many blowers because a friend is in the HVAC business and he gets them all the time, about 10 a year. You can get them on the internet for almost nothing or just ask your local HVAC guy.
Bobby

Ephriam · 07-27-2009, 06:50 PM

I just mounted a 300 CFM blower into a back window in the basement. Found an 8" X 6" adapter and had a local sheet metal guy mount a flapper + mouse guard into the window's metal frame. Also got the speed control. Paid too much for the unit but had to get a quiet one and they're not cheap. At the moment the outside humidity is hovering around ninety so I don't dare turn it on for more than a moment. So I'll put off what I want to do until dry cool fall days are here. Thank you all for the good advice.

Fred

PS: Hung a CO detector in the basement

woodnthings · 07-28-2009, 10:34 AM

You will find out soon enough when winter comes, whether or not your stove will "draw" porperly. I'm still a bit concerned, having burned wood for whole house heat for 10 yrs, in Michigan. Backdrafts stink and bring in unhealthy fumes. I hated that part of the process. Why not add outside combustion air to the stove? Also why not add a fresh air inlet to the shop either like a dryer vent flap or cracking a window on the opposite side of the shop to prevent negative pressure. My 3 speed furnace blower on a 3/4" plywood panel fits on the inside of my awning window. I just open that window, crack another window opposite, turn on the fan and fresh air is brought in for dusty operations and small welding projects.
Good Luck, bill