# Pumping dust outside



## rhizando

I'm sure this has been discussed before, but how many of you are actually doing this. I have the harbor freight dust collector in my basement shop and I am thinking about pumping the dust outside. I dont have any close neighbors and thought this would be the safest solution.

Thanks!


----------



## SteveEl

All the air that goes outdoors has to get indoors from someplace. Besides maybe screwing up your temp or humidity, beware that it can get sucked back down the flues for any combustion appliances (furnace, hot water, etc), and if that happens you could be killing yourself from carbon monoxide. Google "HVAC backdrafting" for more info.


----------



## Burt

I do this. My collector is a portable model with no bag or anything. It is located in a cabinet on outside of wall, then vent using a dryer type vent. My shop is an old garage at rear of property, no neighbors at all back there. I only use electric oil filled space heaters in winter, so negative pressures are no problem. It only runs when I turn the saw on, so minimal heat is lost. Works for me, but I would be hesitant doing so in a basement setup.


----------



## johnnie52

Years ago (when I was knee high to a grasshopper) my Grandda had a blower system attached to the top of his industrial sized planer that captured all the saw dust from the planer and sent it outside to a burlap bag that used to be hung from hooks under the shop eve. It was the only dust collection he had in his shop.

As I remember, it worked fine.

He used a wood stove for heat in the winter and there were never any problems.


----------



## dbhost

There are several drawbacks to this approach.

#1. Not only will you be pumping sawdust outside, but you will be pumping heated / cooled air outside at the rate of, let's say 800 CFM. (Manufacturers lie, this is a generally accepted number).
#2. With 800 CFM air going OUT, you will need 800 CFM coming IN. And if you don't intentionally provide it via something like an open window on the other side of the shop, well nature abhors a vacuum, and that air will come from SOMEWHERE, like out of a fueled appliance like a furnace, water heater etc... pulling Carbon Monoxide into the house instead of properly venting outside. This can have lethal consequences for you, and anyone else in the house.
#3. You will be blowing pollutants outside and dispersing them into the air, so anyone within the reach of the breezes that will carry the fines away from you, will be breathing that stuff in. Say like your children, your wife, your neighbors etc... 

A far better solution would be to go ahead with the most popular modifications to the HF 2HP DC, which is to replace the OEM bags with a Wynn 35A cartridge filter and plastic lower bag, and either install a Thien baffle in the inlet ring, or build a Thien separator on a trash can or barrel of some sort. Realizing you won't be able to get 100% of the fines even with a 5HP cyclone, you really need to also consider adding an ambient air filter of some sort. Shop built ones can save you a ton of money IF you can find a good used squirrel cage blower in good condition either free, or cheap. The contractors around me that gave me a couple of fans were far less than kind to them when the pulled them out, so I ended up buying a Grizzly unit. Still a good unit, not as inexpensive as a shop built model can be built for though. And not the sense of pride in accomplishment...

An ultra basic ambient filter can be made with a 20x20 box fan with a MERV 11 or better filter like a 3M Filtrete Ultimate Allergen duct taped to the intake side. Those rigs work, more or less, but clean the air REALLY slow...


----------



## rhizando

So I guess I should have given some background to my shop. I heat my house with an out door wood boiler so the only thing thats coming into the house is water. I also heat my hot water with this method. I have windows in the basement and wouldn't mind opening the up when I run the system. Sure I would loose some heat but I am only a hobbyist and I don't run one system for a very long time. 

As far as pumping the dust outside, I dont see how that could be that dangerous? As long as its not pointed at the front yard and isn't next to any windows, seems like it would be the same as a say an exhaust vent for a furnance?


----------



## dbhost

Yeah, you are on the right track. That bit of background would have been helpful... 

The big thing is you don't want the fines going to where the people are before they can be sufficiently disbursed. Trees, leaves and such have a great way of cleaning the air. 

Even with blowing the DC collected dust out, you still may want to use a box fan / filter rig near the dust source to clean the air of anything that you may not catch by the DC... Location matters a great deal as well. Since you mention that it is a basement shop, that instantly eliminates the Gulf Coast as a possible location / environment (if you had a basement here, you would have an indoor swimming pool!), so I am GUESSING that maybe you are somewhere in the midwest where summers aren't too brutal, and even with windows open, your heating system can make up for lost heat in the winter. (I have worked in some shops like that when I was MUCH younger). Then venting outside might just be for you. 

You will still want to pop a window open when you run the system though, just to equalize pressures, which might make for cold drafts in the winter, but if the heating is as you say, then no big deal...


----------



## rhizando

Thanks for your help! I am from Upstate, NY where the winters a brutal. Most of that time is spent snowmobiling though :thumbsup:. The summers aren't too bad and I dont have air conditioning to worry about. Also, heating with wood I dont mind throwing a couple more pieces to make up for the heat loss. 

Thanks for the suggestion on the shop air cleaner!


----------



## Nate1778

I do this but actually run it through a cyclone with essentially no filter. During the winter I use a torpedo heater that can keep up but you know when the DC is running. During the summer its a non issue. I am collecting 99% of the matter in a trash can from the cyclone though, it is nice to never worry about a filter. 

A shooting buddy of mine that has a cabinet shop way up in the hills of Kentucky has a big O 3 phase something or other and he vents to the hillside behind his shop with a big O 10" pipe. Pretty impressive suction as I have felt as well as a pile of wood chips, that said he doesn't bother anybody up in the hills either.


----------

