Putting a DC outside.

[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.