# Dust Collection



## eregister (Jan 12, 2011)

I've been reading a lot about dust collection on Bill Pentz site and he advocates a cyclone vented to the outside if possible. I like the idea of the dust that's left after the cyclone getting vented outside as there would be no dust passing through filters to the inside of the workspace. In my shop I will be able to vent to the outside, my question is does anyone know of any regulations about venting dust to the outdoors? Is this a normal/acceptable practice?

Thanks,
Ed


----------



## ChunkyC (Jun 28, 2009)

Remember this, all the air that you exhaust outside, all of that air has to be "made up", brought in from outside. It takes quite the air handling system to make up that much air. If your shop isn't heated or cooled, then just leave the door open. If not …


----------



## dbhost (Jul 20, 2009)

Bill Pentz has some fantastic ideas, that I have bumped head with on several occasions, mostly because he comes at dust collection from an engineering perspective, and not the perspective of what is manageable by the majority of woodworkers. Exhausting your shop dust outside is great if you are working in an unheated, and uncooled space. Which in 99% of the planet is a miserable existence. You will need to get make up air to take the place of what is getting blown outside, and just how clean is that make up air? How much of that fine dust that is being blown outside is getting pulled right back into the shop?

I would think that for most woodworking shops, the ideal is to capture as much dust as physically possible at the source, cyclone separate it to keep as much as possible from hitting the filter, and using a pleated filter to present as much surface area as possible to the air stream, at a fine enough filtration level to keep the dangerous stuff from getting pumped back in to the air. For the most part, 1 micron is the accepted standard, but lower is better…

Once that is done, and the work is done in the shop, it is best to clean the air as much as possible with an ambient air filtration system so that whatever got missed by the dust collector, doesn't just linger in the shop air, but instead gets sucked up into yet more filters.

Once that is done, while I can't prove it yet (no particulate meter of my own) but I would almost be willing to bet, depending on where you live, the air in your shop, should be healthier to breathe than say the air in most major U.S. cities, that is unless your shop IS in a major U.S. city…


----------



## Resurrected (Jan 11, 2011)

I'd say go with it, just remember about the presure your creating inside. Regulations, ah I would not be to concerned if your just a small hobby or home shop. Some LJ's will say different but there bigger shop owners likely.


----------



## Pop (Aug 6, 2007)

It gets cold in Charleston. If your shop big or small is heated venting all that air to the outside will pump your heat out with the dust. I don't know your shop layout, but the ideal way is to put the cyclone in a small enclosed room , use a good filter on the cyclone & use a furnace filter on the air coming back in your shop from the enclosure. Then as dbhost said back it up with a ambient air filtration system.

Pop


----------



## eregister (Jan 12, 2011)

Seems pretty silly but I never considered all the dust I blew outside needed to be replaced, and thus there goes all my heat and a/c. Guess that's why I asked for the help!

All have made very valid comments. I did see a design with the cyclone in a seperate room and I'm thinking that would work the best, I should have enough space to build a cyclone room.

Thanks for the help!


----------



## rieferman (Jan 12, 2011)

I'm venting outside. My shop is an insulated/heated barn, but the construction is loose enough that makeup air is no issue (for example, just the small gaps around a garage door let in a fair amount of air).

Makeup air, if not loose construction like mine, amounts to a window cracked open, or a louvered vent that opens under pressure if you want something easier.

As for taking conditioned air out of the shop… The objects in the room hold a ton of heat. The air is easy to re-heat. Think about opening the garage door in a heated garage. Wooooooo, blast of cold air. Close the door. Two minutes later, the shop is warm again. How? The objects in the room are holding heat. If you're like many, and like me, your DC won't generally be running for an hour straight that often, so your room will be fine in terms of temperature.

In my opinion, the expense, hassle, and space taken up by filters isn't worth the couple pennies in heating cost. I choose to expel outside.

NOTE: If you decide to vent outside, consider saving a boat load of money and use a thien separator instead of a cyclone to catch the chips. Who cares if a cyclone is better at chip collection if the excess is vented into open air anyways? (this assumes you're not blasting the exhaust into your neighbor's kitchen etc.)

As for regulations, my township emailed me and said I'm fine. They do have regulations for larger operations, but for home owner shops, he gave me a pass. He was surprised I even called to inquire.


----------



## GaryK (Jun 25, 2007)

If you should decide to keep everything inside here is what I did:



When it's over 100 degrees outside I like to keep in all the cool I can.

As to what rieferman says about heat might be valid if you keep your shop heated 24/7, but if you are only in there a few times during the week with the heat on, then nothing will be warm and will take a lot of time to warm up.

Washable filters are cheap and last for many years. Why lose you heated or cool air if you don't have to.


----------



## ChunkyC (Jun 28, 2009)

It's a little more than a " couple pennies." I talked with our Refrigeration Engineer this morning and we came up a simple equation. We made A LOT of assumptions to simplify things but for my setup, a HF 2 hp 3450 CFM rated DC, would cost about $1.65 / hour. Assuming that you are raising / lowering the temperature 20 degrees and and energy cost of $0.10 kWH. At a Delta T of 40 degrees, a day like today, then it would cost about $3.30/hr to keep the shop warm.

To get more accurate numbers, there are a lot of other factors that need to considered, heat load, efficiency, relative humidity, and on and on. The point is, it's a little more costly than one might expect to condition the make up air.

If you believe the ratings of the HF DC then it would exchange the air in my shop about 85 times an hour! That's a lot of air moving going on.

Also, if you shop is in the house, someone is going to be complaining about cold drafts at some point.


----------



## rieferman (Jan 12, 2011)

Assuming that a one man hobby shop does not run a DC continuously for hours on end while in the shop, I contend that the heat loss isn't as big of a deal as people will scare you to think. Personally, a lot of my time in the shop is spent figuring stuff out and setting things up. The actual cut takes only a few seconds, therefore the DC is on for just a few seconds.

If you are a production shop that runs your DC non-stop, AND you live in a cold weather climate, AND you have a big budget to buy an expensive cyclone and expensive filters… perhaps venting inside makes the most sense for you. However, if you're like me (a budget-minded, one man, hobby shop, running the DC in spurts, living in a mixed climate, working a couple hours per night and on weekends) building a $30 thien separator, and venting outside (free!... errr, plus killowatts per hour heating I guess..) might work out very well for you like it has worked out for many others.


----------



## crank49 (Apr 7, 2010)

You probably need to bleed a portion of your collector air outside and replace it with makeup air to get rid of vapors and fumes anyway if your shop is inside your home. You can make an air to air heat exchanger to temper the makeup air. Think for example if you had a large radiator, like from a car, mounted on an outside wall. You send exhaust air into the top fluid port and pipe the bottom drain port outside. Now your radiator is being heated or cooled by the exhaust air. If you had an opening behind the radiator letting makeup air pass through a furnace filter and then the fins of the radiator, it would recover a lot of the energy being exhausted outside; almost for free, and it would be filtered air.

The true power of the EPA is not understood by most folks. They have the right, the law, and the enforcement capability to fine any business, any entity, or any person they find to be in non-compliance. You exhaust anything out of a shop, technically you are supposed to have a permit. The paperwork is hell. It's best to just try to stay under the radar.


----------



## dbray45 (Oct 19, 2010)

Do NOT vent your DC outside if you heat with anything other than electic heat. You will pull the fumes into the space or dwelling from the stack as soon as the heat comes on. Put the DC in a different room that is vented back to the shop but maintain the envelope. This will help with noise as well.


----------



## ChunkyC (Jun 28, 2009)

I agree to politely disagree. I know that when I use my planer, jointer, router table, et al, the dc runs for 5 minutes or more, not seconds and I'm barely a hobby woodworker.

David is right. The CO is a great point that I hadn't considered (I live in an all electric world!) A DC could easily cause a down draft in a gas fired furnace pulling the CO into the shop.


----------



## Resurrected (Jan 11, 2011)

LOL

Thread is on regulation.

Eregister- Small hooby shops should be fine. Just call your local inspector if you want to be 100% for sure.

As far as loss of heat and all the other stuff, everyone has their own opinion. Do whats right for you and ignore the rest.

Just be safe doing it.


----------



## eregister (Jan 12, 2011)

Great information, thanks to all for taking time to offer your suggestions.

I'll be posting progress pics as I get underway.


----------



## dbray45 (Oct 19, 2010)

The way I look at it, if you govern your life on regulation, you wouldn't do much or you would end up killing yourself because there isn't a regulation that covers it. The whole idea here is to be safe. Yes, people will do what they will and that is a good thing.

It is not just a CO issue here, ask any firefighter how many house fires they put out caused by a downdraft in the fireplace, I know a lot of people that use wood burning stoves for heating their shops. When you introduce moving a lot of air accros a fire as that of a DC, you create in essence, a forge - with smoke. To test this, stick your DC under your grill vents, start a nice wood fire in ithe grill and turn your DC on. Call the fire dept first - saves on total damage. Keep in mind that many flues are smaller than your average DC.

For a gas or oil furnace and water heater - it is strickly a CO problem. This is easy to test with a CO detector and by putting your DC outside and putting a 6" hose the the same room as the furnace. Set the CO detector on the floor, CO is heavy. This takes less time than sucking air from the other room but the overall result is the same.

Keep safe.


----------



## scubastine (Feb 7, 2010)

This is a great topic. I live in SE Florida in a concrete home with a one car garage shop. A/C is expensive and opening the garage door doesn't keep me in good with the neighbors. I have a friend in the HVAC biz and he is suggesting i build the outside "Closet" i discussed with him. This frees up valuable space. With the closet insulated, it would also be quieter than my neighbors pool pump or a/c compressor.His recommendations are to maintain the makeup air back through the wall from the closet with filters as others have mentioned here. The concern is sizing the return area as to not defeat or impede the airflow through the DC. He is doing the math for me, and i would think that if you were to give the specifics; CFM's, Cubic Ft of workspace air etc, to a "friend" in that field, they could help with the configuration and the math.


----------



## dbray45 (Oct 19, 2010)

This would work - if you were to make a baffle before the filter so the noise would have to make a couple of turns, the noise would be reduced as much as 60%, maybe more - and - heavier dust would fall before getting to the filter.


----------



## ScottN (Jan 24, 2011)

Exhausting your dust collector outside is totally your choice. The reason I wouldnt do it is you would have NO way of controlling the humidity in your shop.

I have a simple temp and humidity gauge in my shop and I try and keep it between 40%-50% humidity. Its why you wait to use the wood yo just picked up and let it sit in your shop for a few days to let the wood accumulate to your shops humidity. Or the reason you let hardwood flooring sit for a couple of days in your house before installing.

Maybe give it some thought.


----------



## JasonWagner (Sep 10, 2009)

I have my dust collector (1100 CFM) in a full basement shop. It is hooked up to a Thein-style chip separator then vented outside. I justified this because I only use my dust collector for seconds to a few minutes at a time since I'm just a hobbyist. I tend to turn it off and on between cuts. I have a propane furnace in the basement and crack a window if I'll have it on for a few minutes, but usually don't even do that. Usually the furnace isn't running (I can hear it) and the leaks and gaps around doors is enough to prevent creating negative pressure. I love not having dirty bags or having to upgrade to expensive cartridge filters and cyclones. My situation is kind of specific. I do not have neighbors to bother with exhaust sounds and I do not use it very often. Also, there has never been any noticeable dust found outside by the exhaust.


----------



## ND2ELK (Jan 25, 2008)

Why are you wanting to vent your cyclone outside. With my .1micron filter canister I have no dust and no loss of heat or cool. I also have a muffler on my cyclone which makes it quieter than a shop vac. I do not run my DC hours on end but quite a bit when machining stock. It does not take long to remove heat or cool with a small 14 X 21 shop.


----------



## Resurrected (Jan 11, 2011)

ND2ELK

Do you hire a cleaning lady for your shop. I think a surgeon would operate on that table.

I forgot how well your cycclone set up was put together.


----------



## chickenguru (Mar 15, 2010)

Wow. What a great looking shop.


----------



## clafollett (Feb 17, 2011)

ND2ELK, all I can say is wow! You've got a tight little operation going for just a a 14'x21' shop. Impressive!


----------

