Putting a DC outside.

[Chase Gregory]

Is locating the DC unit outside of the shop walls a particular problem?

I did some searching but didn't spot this topic - though I read a LOT about DC's inside shops...enough to cause respiratory problems of another sort...

I have a 12x16 lean to off the back of my current shop/barn and it just seems logical to put a DC outside like a compressor. Much less noise and takes all the waste out where it's destined anyway!

Would this also preclude the need for .5 micron bags and such or would I then be required to provide masks for the resident deer and rabbits?

I'm nearly a mile from the nearest paved roadway and at least 1/4 mile from the nearest neighbor...and I'm also the only resident around devoid of some form of livestock (excluding my 3 children of course). So to be a nuisance I'd have to be much more creative than an outside DC...perhaps a waste incinerator would qualify...

This exo-shop DC consideration occurred to me as I visited a Harbor Freight (Chinese Invasion) that will be opening next month down in town. They're hiring folks so I stopped by to ask when they were opening and if the current sale price on DC's would still be in effect. They said to print any HF internet coupons I like and they'll honor them when they open next month.

So I'm thinking that throwing $170 away on a cheap dust collector will at least handle chip movement to the rear of the barn better than a shop vac and the 30 micron bag won't matter to the mower & golf cart and steel and seed stored back there.

Meanwhile I'll still keep the 8x8 shop door open and the 36" box fan running and usher the small stuff out the front with all the dust from the floor.

Anyone running thier DC outboard?

Chaser

[Jim Becker]

It's not unusual for a cyclone to be located outdoors in some pro (and non-pro) shops, but a single stage system will need to be under-roof. If you just use the blower to move dust and chips, you'll still need to protect it from the elements.

[Scott Rollins]

Be careful if your have a gas water heater or furnace in the workspace as the exterior vacuum will pull the exhaust fumes into the workshop through the exhaust vent. This happened to me on a cold day recently and I put a box fan in the window to remove finishing fumes...I ended up with more fumes and my CO2 alarm going off.

[Chase Gregory]

It's not unusual for a cyclone to be located outdoors in some pro (and non-pro) shops, but a single stage system will need to be under-roof. If you just use the blower to move dust and chips, you'll still need to protect it from the elements.

Oh, absolutely!

It's a 12x16 roofed area. I'd probably have to add a hardware cloth cage around the DC to protect the bag from field mice...infuriating little fellows...maybe the dust will get 'em :rolleyes:...

[Chase Gregory]

Be careful if your have a gas water heater or furnace in the workspace as the exterior vacuum will pull the exhaust fumes into the workshop through the exhaust vent. This happened to me on a cold day recently and I put a box fan in the window to remove finishing fumes...I ended up with more fumes and my CO2 alarm going off.

Workshop has no heat :(. Small birds can fly in and out with wings outspread. No LP or natural gas on the property.

Good advice! Also wouldn't want dust getting used for combustion air for a gas appliance!!!:eek:

Chaser

[Jeff Miller]

Mine sets on the other side of the wall here and exhausts directly outside and I never see any dust or chips come out the exhaust.................unless I forget to check the barrel and it gets full:eek:




http://i44.photobucket.com/albums/f32/woodfarmer/New%20Shop%20Pictures/shop005.jpg



Comes in right where the Y is. Sucks bigtime

One of these days I gotta rearrange that lumber rack:o


http://i44.photobucket.com/albums/f32/woodfarmer/shop/shop006.jpg



Jeff:D

[Rob Will]

If you do not intend to return the air into the shop and you don't live in town........why bother with a bag type dust collector?

If you do use the HF DC, I would install a plywood box with a vertical baffle in it as a pre-separator. Hang it on the wall and put a garbage can cleanout below.

The HF DC goes downstream pulling air through this pre-separator box. Most of the heavy chips fall out before they ever get to the DC.

Rob

[Tim Marks]

You really don't need the dust collector for what you are talking about. All you need is a blower, and I bet you can buy something much more powerful then the HFDC version on ebay for cheaper. Just run it through a pre-separator ("trashcan cyclone" lid on top of a 55 gallon burn drum) and exhaust it out the back of the barn.

Don't get me wrong, I have the HFDC and find it works, but I gotta believe that in an application where you just need a blower that you can find something nearly as cheap that is twice as good (and the HFDC will suffer if you try to pull air through a tube longer then a few feet). The HFDC runs 14A at 120V which is pretty similar to the rating you see on 1-1.5 Hp DC...

There are several "real" 2HP DC for sale on ebay right now (22A at 120V sounds more like it). Look for something like that.

Maybe this: http://www.pennstateind.com/store/dc3xx.html (still only 1.5 Hp). Oneida and Penn both used to sell just the blowers they use in their cyclones, but don't advertise them anymore. Clearvue motor+impellor+housing would run you $700.

[Matt Meiser]

I vent my cyclone outside with no ill effects on heating. I think it helps that my furnace is a force draft unit with a blower to force the gasses out the flue. I didn't notice any significant changes in my gas usage when I switched to outside venting either. About the only thing I do notice is some fine dust that occasionally sticks to the siding outside due to either wind and rain or static--not sure which. It gets cleaned off by a hard rain though.

I agree with Rob--if you aren't going to do a cyclone, just put in some kind of drop box and forego the bags. And as Tim said, you might be able to find a deal on a good used blower. Another option would be Grizzly's G1029 DC unit which has a 2HP blower with a 12" fan for about $250+shipping in the new catalog.

[Art Mann]

Lets do a little math here. My shop is 24 * 28 * 9 or 6048 cubic feet. As best I can tell, my dust collector pulls abut 750 cfm. That means it is capable of displacing the entire mass of air in my shop in about 8 minutes. It is currently about 60 in the shop and 20 outside. It seems to me that if I discharged the warm shop air outside only to be replaced with outside air, the temperature inside and outside would be roughly the same in about an hour. Is my logic flawed somehow?

[Matt Meiser]

Art, the theory is right, but I'm just not seing it happen. I know of a few others who do this too, without trouble.

One theory I have is that the building, floor, tools, etc are all at 62 degrees and they rewarm the air quickly. I'm sure the furnace does run more during the time the blower is running, but in a hobby shop, if you look at the percent of time that you are actually running the blower it is tiny in the big scheme of things.

[Rob Will]

Lets do a little math here. My shop is 24 * 28 * 9 or 6048 cubic feet. As best I can tell, my dust collector pulls abut 750 cfm. That means it is capable of displacing the entire mass of air in my shop in about 8 minutes. It is currently about 60 in the shop and 20 outside. It seems to me that if I discharged the warm shop air outside only to be replaced with outside air, the temperature inside and outside would be roughly the same in about an hour. Is my logic flawed somehow?

Let's see, after the first 8 minutes the inside temp would be 40. After another 8 minutes it would be 30. Another 8 minutes, it would be 25........

It seems to me that absent any furnace input, and with uniform air mixing and removal........it would only take about 30 minutes to completely remove the heat from your shop.

Perhaps more importantly, the comfort zone is lost very quickly (within the first 5 minutes) and your furnace would probably run continuously to try to keep up.

Rob

[Abe Low]

My shop is unheated but being retired, I can wait until the sun warms it above 45 degrees. If I needed to have it heated I would still have the cyclone outside to reduce noise and increase interior space and I would route the outflow to a bank of filters that would allow clean air to come back into the shop. My experience with the cyclone (Clearview w/ 3 hp Delta blower) is that nothing visible exits the cyclone until the 55 gal barrel at it's base is 3/4 full.:)

[Rob Will]

Art, the theory is right, but I'm just not seing it happen. I know of a few others who do this too, without trouble.

One theory I have is that the building, floor, tools, etc are all at 62 degrees and they rewarm the air quickly. I'm sure the furnace does run more during the time the blower is running, but in a hobby shop, if you look at the percent of time that you are actually running the blower it is tiny in the big scheme of things.

Matt has a good point but any heat unit removed from the building must be put back.....by the furnace. This includes warming the tools back up to 62 degrees. I can't argue with the hobby shop theory though. Sometimes we worry about things that are not important with intermittent use. In the big scheme of things, extra attic insulation might make a bigger difference.

Rob

[Tim Marks]

Let's see, after the first 8 minutes the inside temp would be 40. After another 8 minutes it would be 30. Another 8 minutes, it would be 25...
But is he running his dust collector continuously? Sure, it would get chilly if he was planing several hundred feet of wood all morning. But I generally only run mine for a few moments at a time.

That being said, be careful Matt. It is very dangerous to put a negative pressure on a house heated by oil, even if it is a forced draft furnace (you are taking about outside air being used for combustion, not just the fan on the furnace's exhaust pulling fumes out). If your shop is your basement where your furnace is located, it would be easy to pull carbon monixode out of the furnace into your shop. Please tell me you have a CO detector in your basement if you are going to do this?

[Chase Gregory]

I do like the thought of just getting a blower motor and dropping chips in a 55gal drum as I have plenty of those around. Man this is sounding easy!

I have 220v and so any leads on a 220v blower motor...like from an abandoned DC...would be of interest to me.

Can that HF $170 DC be rewired to 220v? Probably not worth it as it won't make it any larger...

My shop maintains the same interior temp as exterior presently - loss of heat is moot because I'm not out there when it's colder that I like.

Perhaps in my future shop I'll route makeup air through a filtered pre-heating chamber that's warmed by my woodstove (kept outside to burn scraps and fallen pecan limbs)...

Chaser

[John Newell]

Opinions on the following? A half-breed setup with a good portable DC *inside* but with the bag replaced with large dia duct that vents outside.

Would this be practical?

[Chris Singletary]

Chase,
Where in Hahira do you live? I also live there and have a cyclone separator I would be willing to part with. I built on of the Pentz cyclones and put it in front of a Jet DC-1200 Works great.

[Matt Meiser]

That being said, be careful Matt. It is very dangerous to put a negative pressure on a house heated by oil, even if it is a forced draft furnace (you are taking about outside air being used for combustion, not just the fan on the furnace's exhaust pulling fumes out). If your shop is your basement where your furnace is located, it would be easy to pull carbon monixode out of the furnace into your shop. Please tell me you have a CO detector in your basement if you are going to do this?

Detached shop with a propane furnace. And yes I have a CO detector which has never gone off. Even if I run my exhaust fan I don't have trouble and that moves a lot more air than the DC--something like 3000cfm. That will actually cool the shop off if I open a window, otherwise the fan gets starved for air.

[Tim Marks]

That sounds a lot better... I wouldn't be too worried about prpane in a separate workshop.

My last workshop was the basement of my house with an oil fired furnace in it, and I am pretty sure that it would have filled my house with CO and soot if I put a suction on the basement.

[Matt Meiser]

Remember that my furnace is forced draft too. A more conventional unit might be a problem.

[David Wilhelm]

I just got a HFDC for the blower to mount over head and blow out the the back wall of the shop. Running 18' or so of 4" pipe? with 3 down hoses. It's not been open should I take it back and get something else? all i want to do and suck up the sanding dust on my lathes.

[David Giles]

Chase, I have an outdoors DC that is under continuous tinkering. Based on your geographic location and shop, you sound like an ideal candidate to vent outside. Couple of suggestions. First, go with 5-6" ducts and as big a blower as you can get. Upgrading my ductwork made a huge difference when using my little 1.5Hp Jet. Second, free vent into a box, the yard or something, but ditch the inlet separator and the discharge filters. Both add tremendous pressure drop to the system which reduces the overall air flow. Third, locate the vent downwind from your back door!

Good luck and don't make it more complicated than it needs to be!

[John Newell]

Separate blower or commercial DC unit? If separate, what would be the best source(s)?

[Rob Will]

I once tried blowing my chips into a large gravity wagon. The velocity of stuff coming out of the fan was very high and blew most of the chips right out on the ground.

If the objective is to let chips fall out of the air stream, why accelerate everything like a fire hose?

A pre-separator or "drop box", if properly designed can let the bulk of your chips fall directly into a trash can. All you need is an extra trash can or two.

A drop box also protects your fan blades from the occasional chunk of wood going through the vac system.

I agree that the bag filter is a huge restriction. If you don't need it, dont use it.

Rob

[Bill Pentz]

Although logic would have you thinking that if you exhausted half your shop air every eight to ten minutes, you would have the temperature drop quickly the reality is similar to air cleaners. They don't clean even close to half the air after moving the total volume of air in your shop. Heat like dust ends up spreading so fast plus it warms up the incoming air that the amount of dust and amount of heat lost is far less than expected. I can vent outside with a 5 hp and stay comfortable at near freezing temperatures with a couple of the Costco parabolic heat dishes. But like Abe, I am mostly a fair weather woodworker. One of these days I am going to ask one of my HVAC engineer friends how to actually compute the heat loss because I think air cleaners work very similarly which is why they take so long to significantly reduce our airborne dust levels.

[keith ouellette]

Doesn't a room 25ft by 25 ft room with 10ft ceilings have 6250 cubic feet of air in it? At 1000 cfm it would take 6 min to move all the air out of the room. Any conditioned air would be gone to the outside elements. Shouldn't the dc be vented back into the work space through a filter?

[Rob Will]

Doesn't a room 25ft by 25 ft room with 10ft ceilings have 6250 cubic feet of air in it? At 1000 cfm it would take 6 min to move all the air out of the room. Any conditioned air would be gone to the outside elements. Shouldn't the dc be vented back into the work space through a filter?

No, I think in 6 minutes the fan would remove half of the conditioned air because outside air is being mixed with inside air while this is going on.

Sort of like if you have a glass of lemon juice and a glass of water (equal amounts). Pour them both in a pitcher (your shop) and drain one glass out. What you end up with is 50 / 50.

After another 6 minutes, you dilute the existing air by another 50%. Now it is 75 / 25.

Rob

[Bill Pentz]

I hear this concern about venting outside too much. It is not nearly as big of an issue as most think. Rob is on top of why.

A 25'x25'x6' room has 6260 cubic feet of area. Removing one cubic foot of air from this room is going to bring in one cubic foot of air. Assume an indoor shop temperature of 70 degrees F and outdoor temperature of 20 degrees F. After you blow one cubic foot out the incoming air is going to mix with the existing air. That means the new temperature is 6249 cubic feet at 70 degrees plus one cubic foot at 20. Multiply 6249*70 and add 1*20 then divide by 6250 and we get a new air temperature of 69.9936. Do the same math again for the second cubic foot blown out starting with that new 69.9936 temperature and bring in one more 20 degree cubic foot giving 69.98720 for our new temperature. After blowing out our full 6250 cubic feet of air we are still left with a room temperature of 44.4740 degrees. With a typical dust collector and 4" ducting we are going to remove 350 cubic feet a minute. Divide that into 6250 cubic feet and it will take running our dust collector for 17.85 minutes to lose about 25 degrees. With my cyclone at 1000 FPM it still is going to take 6.25 minutes.

In reality we actually do stay quite a bit warmer because the air leaving and air entering tend to create a racetrack that does not so much affect the rest of our shop air, and in cold weather we can turn our dust collectors off without having to worry about the motors overheating from too many start stop cycles.

[keith ouellette]

No, I think in 6 minutes the fan would remove half of the conditioned air because outside air is being mixed with inside air while this is going on.

Sort of like if you have a glass of lemon juice and a glass of water (equal amounts). Pour them both in a pitcher (your shop) and drain one glass out. What you end up with is 50 / 50.

After another 6 minutes, you dilute the existing air by another 50%. Now it is 75 / 25.

Rob
But the bottom line is you loose heat/ ac, right. Down here in Florida that hot and very humid sumer air is very noticeable if you forget and leave the dc system on for even a short time. Thats why I am going to have to vent mine back to the shop.

[Bob Feeser]

I know a guy who has a leaf blower stuck in the wall of his shop, and that is attached to his DC 6" tubing system in his shop. Wood chips, sawdust, etc are not challenge. He just vents it into a lean to outside room. Unfortunately leaf blowers are not designed for continual use, so he has to replace them periodically.

Pertaining to venting outside with a dust collection system, I wish I could do that, but my neighbors are too close. I do have some input though. My shop is in the basement, which is completely finished. A separate room houses the heat pump, natural gas backup furnace, forced air. In the shop I have a salamander 55,000 btu kerosene heater. I do not leave the vents open to heat the shop during the winter. When I go down there to work, I turn on the kero blast heater for about 10 minutes, with everythng closed up, with me not in the room. The room, the tools, and everything gets heated up real well. Then I enter the room, and open a window and put a fan in it, and open a window on the other side of the shop a little. So I have a clean air flow. Dust easily exits the room. The kero blast heater is hooked to a thermostat which I keep set at 70 degrees. When the air cools down, it automatically kicks on. If I am done creating dust for a while, let's say for glue up, I close both the windows, and open the regular forced air heating vents, for clean air heat. It works great.
Pertaining to the CO2 concerns, I do have a natural gas water heater as well in the furnace room. That room is sealed from the shop, even in the ceiling, although it breathes from the room alongside it, which is also sealed from the shop. In plain words, air is not being drawn out of the furnace room, and positive air flow is possible because this home was built in the 50's and has the 3/4' stips keeping the cinderblock walls off of the plaster board sheets. So the walls breath all the way through to the attic, which has sophit vents. The whole system works beautifully.
I know others will suggest the propane heaters of the type I am talking about, rather than kerosene, and even more will say use the ceiling radiating models, but the kero unit works well for me. When the air is changing, the cone gets red hot, and it burns the fuel so efficiently, that you don't really smell anything, and the fresh air change is so frequent, it doesn't matter much anyhow.
My dust collector is a Dust Force with large bags, that is located right next to the venting window that the fan is in. Even those .5 micron bags are spewing ultra fine particles in the air, so when I do not have a fan in the window, my mask is on. I still wish I had an outside dust collection system, with a lean to room. That would be great.
By the way I have an off timer hooked up to the kero blast heater, so if the thermostat kicks it off, and I forget it is on, the timer expires, and prevents it from going on when I am not there. That is important, a heater of this type, running out of fuel, running sporadically, is a challenge, even with a detector built in to prevent restarts when there isn't a flame.

[Tim Marks]

I know others will suggest the propane heaters of the type I am talking about, rather than kerosene, and even more will say use the ceiling radiating models, but the kero unit works well for me.
Using an unvented propane heater will put an incredibel amount of moisture into the air. Once the room cools back down, it will probably condense out of the air. Maybe not a good idea when you have alot iron machienry that rusts.... kerosene is a better choice, since it will act to dry the air in the room instead of make it more humid.

Keep an eye on the expiration date on your CO alarm... they don't last forever.

[Bob Feeser]

Using an unvented propane heater will put an incredibel amount of moisture into the air. Once the room cools back down, it will probably condense out of the air. Maybe not a good idea when you have alot iron machienry that rusts.... kerosene is a better choice, since it will act to dry the air in the room instead of make it more humid.

Keep an eye on the expiration date on your CO alarm... they don't last forever.

Tim,
Thanks for the tip. I am no longer sorry that I didn't buy propane instead. I do have a natural gas wall unit out on the Veranda/greenhouse addition, that I rarely have to turn on, and that does create moisture just like you spoke of condensing on the glass windows.

[David Giles]

Now that Bill has moved into calculus territory with his heat loss mathematics, we need to add in the heat generated by cutting wood. The dust collector wouldn't be on unless another machine was in use. And all of the energy from the table saw ultimately ends up as heat from friction. So what is the temperature gain from 6-12 amps at 220V being pulled from the table saw or jointer?

[Chase Gregory]

Unless you designed some pretty comprehensive airflow into your shop you cannot exchange all of that air in any short amount of time - it's an exponential process even w/ HVAC systems - you exchange some of it repeatedly.

The DC will pull a relatively narrow path through the room, if it's even a traceable path, via a point source. So it is a very inefficient means to exchange the air or affect the room temperature.

Some of the closest air to the DC inlets is warmed by motors and operators.

Just design your makeup air to filter in through a network of 500w incadescent fixtures...:D. You won't need to add any more heat than that!

Chaser

[Ben Grunow]

Bill, we routinely install systems in the houses we build that allow the air exhausted by a kitchen hood to be replace with heated air that is drawn in through a fresh air intake and heated prior to being blown into the living space. My understanding is that the HVAC guys are just trying to match the cfm (up to the highest rating on the air handler/furnace blower) of the exhaust fan to try to replace the air being exhausted at the same rate.

That said, it seems to me that this is probably overkill as the heat loss is slower (as you say) and less immediate. I think the more important factor is the overall pressure within a house as there is potential to backdraft heating sources and fireplaces and I have even seen a kitchen where the door is very difficult to open when the hood is on full power.

My shop DC exhausts outside and I froze today after running it for half an hour of router table work. I plan to bring the exhaust in asap. It is a waste of energy in a cold climate.

[Steve Clardy]

My 4hp unit is outside on a concrete pad.
I don't run bags. I just blow it into a pile outside.

[Bill Pentz]

My 4hp unit is outside on a concrete pad.
I don't run bags. I just blow it into a pile outside.

I’m with Steve on this. After we work all the numbers, add in for heat generated by our tools and compensate for the dust collection basically creating a circle of air, the bottom line is there is really not that much heat lost, particularly if you only run your dust collector while making wood dust. I seriously doubt that running my cyclone full out while working in my shop on a 20 degree day outside would come close to what my health insurance and I pay for my breathing treatments, supplemental oxygen, sprays, and pills.

The issue with getting rid of the fine dust is just like getting rid of the heat. A good sized exhaust fan or even large air cleaner is just not going to get rid of enough of the fine dust fast enough to keep from failing an air quality test.

Worse, because the dust we miss collecting tends to stick around for months to years and is easily launched airborne again and again by airflows in our shops, those who have poor fine dust collection quickly build up dangerously unhealthy amounts of fine air borne dust. By venting outside we don’t fix the collection problems but at least reduce this dangerously high buildup of the fine invisible dust.

bill

[Johnathan Bussom]

Is locating the DC unit outside of the shop walls a particular problem?

Anyone running thier DC outboard?

Chaser

Chaser,
My shop consists of a one car garage, I built an addition on the side specifically to hold my DC and air compressor, I have a Grizzly 1029 DC wired 220 with a remote switch inside the shop, outside the addition I have 2 55gal plastic drums stacked that collect 98% of the dust/chips before it gets to the dc, the bags on the dc only need checked/cleaned about once for every 4 times I remove 55 gal of chips from the outside bottom barrel. Unless something comes undone I seldom get any dust in the shed (as I call it) but it has happened once.

Noise, I am glad it is outside, I turn it on and hear the startup and know it is working, then I turn on whatever I am using which drowns out the DC quickly. My biggest problem in the winter with the DC is that I don't use it lest I have several pieces to cut/plane/route/turn

John