[OP]
Contributor
I have 3 hp shop fox dust collector and after running my wide belt sander for not to long my Dwyer gage goes from 3.5 to maxed out at 5+ I am thinking about venting outside in the non winter months. Closest window is pretty much straight shot of 20'. Not sure if run would be a issue?
Member
I live in Michigan and vent outside year round. If you look at OSHA regs, the really fine particels go right through your bags and remain inside.
Do or do not, there is no try.
Member
i also live in Michigan and likewise vent my DC (3hp cyclone) outside year-round. i don't have to purchase expensive filters which i don't believe catch the really tiny stuff that is the most dangerous. yes, i have to open a door or crack a window when running the DC, but even in the dead of winter, the heat loss is FAR less than you would suspect. while much of the warm air in the shop gets sucked out and replaced by cold outside air, there is enough heat retained in the "stuff" (e.g., equipment and other things) in the shop that the heat loss is minimal. i recently ran my DC on an incredibly cold day (about 10 degrees outside) for close to 30 minutes (with the window cracked) and the temp in the shop dropped less than 10 degrees (an amount that the heater quickly replaced when the DC was turned off)
Member
I vent my 1Hp DC outside, the dust goes through a Thien style separator and I don't see anything going outside. I live in SW Louisiana so heat loss is not a concern, in the summer I try not to work in the work shop when it is too hot as I don't like to run the window A/C. When ever I get around to it I plan to vent my 2HP DC with a Thien separator outside also.
Member
I'm in the cheese state too. Vented mine outside only in the summer. Was about 15' with a 90° at the end. My frugal nature just couldn't justify doing that year around.
Member
Your filters are loading up due to the fines. You don't say if it is a bagger unit or cyclone unit. Either way, a full dose of sanding dust requires a lot of filter area. If you keep doing it, the filters will blind and not clean well. In other words, your clean pressure drop will be higher.
You'll be fine on the duct losses for venting outside. If you feel you have a lot of dust in the outlet (sounds like you do since filter pressure drop is building quickly), just keep your runs as straight as possible and probably go with 6" or 7". If the outlet air is "clean", then you can go up in duct size. Typical would be to run it at about 2500 FPM. This is usually an economical point for minimizing energy usage duct costs but it depends on the details of your situation.
Mike
P.S. Consider any ill effects from drawing air from other spaces attached to the shop or gas appliances. Your shop will be under negative pressure when you vent outside.
Member
Mike,Originally Posted by Michael W. Clark
That is great advice (that I neglected to mention). You're right, if you're venting outside in the vicinity of gas appliances there is the potential for mayhem. As I understand it, one of the biggest concerns is that your DC will "suck back inside" the flue/exhaust gases that would otherwise be vented outside, thereby creating a nasty potential fire hazard. Please correct me if I'm misstating this.
Member
Not so much a fire hazard but death hazard due to carbon monoxide poisoning! CO is a colorless, odorless gas present in most furnace and hot water exhaust gases. Plus it accumulates easily in the blood and is difficult to purge. It's bad juju!!
Member
I vent my 2HP Oneida cyclone outside year round. No more wasting time cleaning the filter. I was concerned about wasting heat when I first did it, but it actually surprised me how I can run the dc for a long time when it is 10 degrees out and not really drop the temp in my shop much. I have no issues with it and would not go back to a filter. As was stated above, just be aware of proximity to furnaces / boilers etc. My shop is off the back of my garage, so not a problem for me.
Member
I researched and posted about this quite some time ago so my numbers may be wrong, but for those of you who are concerned about heat loss if you discharge your DC outside-
The structure (walls, ceiling, floor) and the contents (machines, cabinets, wood, etc.) of a typical shop have approximately 1000 times the thermal mass of air.
What thermal mass means for comfort- if you run your DC only when you are using a machine and then turn it off, cold or hot air that was drawn in from the outside by the DC will be rapidly warmed/cooled by the thermal mass of the shop until it is at the same temperature as the shop's thermal mass. It will take many cycles/minutes of DC time to result in any significant amount of temperature increase or drop. So, unless the weather is extreme and you turn the DC on and leave it on for your entire shop session, venting outside has little impact on comfort.
Depending on your climate, there is one additional parameter however that won't be affected by the your shop's thermal mass- humidity.
What thermal mass means for energy costs- obviously this will depend on the cost of electricity and/or gas in your particular area, but yes you will need to use more energy to return your shop to the desired temp after a long session with the DC running. If you normally turn off the heat or AC when you are not in the shop, then the impact won't be much different than turning on the heat/AC when you first enter your shop each day.
As I said above, be careful if your shop is attached to the house and either has one or more gas fired appliances. Even though there may be a direct path between furnace and DC intake, (reverse) flue gasses can still infiltrate and linger in your shop in sufficient amount to be deadly over time. I had an incident in my old shop years ago. There was a gas furnace and water heater in an adjacent room. I didn't smell anything but after a short shop session during which I ran the DC, I had a splitting headache, mild nausea, and slight reddening of my finger nails- all indicators of CO poisoning.
[OP]
Contributor
my dust collector system is cyclone and have propane boiler that takes air from the shop when burning. i dont want to vent outside during winter. wright now i have a 16' by 8' grage door that is insulated but with the way grage doors sealed is a heat loss. I think am going to take one of upper windows in grage out and cover it with plexyglass and run the exast through that.
Member
The only proviso when venting outside is make sure the vented air is not near any open doors, windows etc that are open to replace the air that is being extracted otherwise the dust can be returned into the workshop. Totally isolating the DE from the work area and venting outside is about the best thing you can do.
Chris
Everything I like is either illegal, immoral or fattening
Member
This is a great discussion and I'm glad to hear that others are venting outside. I've been doing it for several years with a similar 3 hp DC with great success. I don't particularly notice much heat loss, although I also don't run my DC constantly either. For certain, you will get better performance out of your DC by eliminating the efficiency loss created by the filter.
Be aware that a single stage DC will pass a lot of fine dust outside when sanding. Same thing with chips if you let the bags get too full. If you can vent into an area that your wife doesn't care about, it might not be a problem. Otherwise, you might want to build a dust containment box with some crude filters outside to keep the outside of your shop from looking like a dust bomb went off. I just built a big plywood box with a door made of screen door material. I periodically blow the caked dust off of the screen. The finer dust not captured by the screen pretty much floats away. Once or twice per year, I open the box and scoop out the accumulated chips and dust.
Member
What do you do about the sound? Does the guy next door complain?
Dan J. Michigan
Guest
Only until he succumbs to nasal and/or lung cancer.
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