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Venting dust collector outside

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Forum topic by agallant posted 11-23-2016 12:34 PM 898 views 0 times favorited 8 replies Add to Favorites Watch
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agallant

551 posts in 2723 days


11-23-2016 12:34 PM

I’m sure this had been discussed to death but I can’t find an exact answer. I have a 36×14 detached work shop on the back corner of my lot. It has electric heat and A\C. If I vent my dust collector outside is it really going to affect the temp in the shop? I don’t use it unless I have a tool on and am in North Carolina where the weather is pretty stable.


8 replies so far

View CharleyL's profile

CharleyL

221 posts in 3200 days


#1 posted 11-23-2016 03:03 PM

When you take air out of a building, outside air is going to come in to fill the vacuum created. It will get in through any way that it can. If you seal up the building tight, the efficiency of the vacuum will be reduced. Some of your heat is going to go out through the dust collector exhaust, but if you only run the exhaust for short periods, the cold air coming in will not significantly reduce the inside temperature. It will all depend on how long you run the dust collector and how much air is exhausted through the dust collector.

I’m also in North Carolina, North of Charlotte, and m shop is heated and cooled by a heat pump. To me, it’s the safest way to both heat and cool a shop in this area of the country. I also exhaust my dust collector outside, but I ‘m not in my shop full time and I too only run the dust collector when it’s needed., so the cost of additional shop heating or cooling for my shop isn’t very significant. My heating/cooling system isn’t even on when I’m not working there, unless the outside temperature will be below freezing or above 90 deg. The more heated or cooled air that you exhaust from your building, the more you will need to pay for additional heating or cooling to condition your shop air. It will all depend on this, and I have no way of knowing how much this will cost you over and above your present heating/cooling costs. It will all depend on how much you run your dust collector and how much air it exhausts. I just consider it the cost of keeping the dust out of my lungs, and deal with it.

Charley

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agallant

551 posts in 2723 days


#2 posted 11-23-2016 03:49 PM

It sounds like I’m in the same boat as you. I don’t use the shop every day. I leave the heat on 60 and kick on a karosean heater if I need to. As for the ad that is set for 82.

View Jim Finn's profile

Jim Finn

2577 posts in 2758 days


#3 posted 11-23-2016 11:03 PM

My dust collector is in a separate shed from my small woodshop. I am in a high desert of Texas so AC is a must in the summer afternoons. I have two window units that keep up nicely with the dust collector. Not a problem for me. I spend about 35 hours a week in my shop.

-- No PHD, but I have a GED and my DD 214

View mrbob's profile

mrbob

182 posts in 405 days


#4 posted 11-23-2016 11:25 PM

I wont/cant comment on heating/cooling cost, but you if you exhaust to the outside for the DC to work at its best it needs replacement air coming in at the same rate it is going out.
So if you have a 1200 CFM DC, you need to have a way for 1200 CFM coming in. You could do that one way by putting in a damper grill in a wall with the closing flaps on the inside, that way when running the DC they would open up and let air it to the shop to replace what air going out from the DC..
Kinda like a clothes dryer vent that has flaps on it but in reverse.

View JBrow's profile

JBrow

1274 posts in 756 days


#5 posted 11-24-2016 12:00 AM

agallant,

If the shop has 8’ ceilings, the volume of the building is about 4000 cubic feet. If a dust collector drop is sucking air from the tool (and hence exhausting air to the outside) at the rate of 400 cubic feet per minute, then in about 10 minutes all of the conditioned air in the shop will have been exhausted. The exhausted air will be replaced by outdoor air through a window or leaking into the building (which is of course unconditioned air). Since planing a stack of lumber or a sanding session can take some time to complete, I would think exhausting the dust collector outdoors will adversely affect the heating and air conditioning bill as well as the comfort in the shop.

If dust collection air is vented outdoors, then a heat exchanger through which make-up air passes, heated or cooled by recovered energy from the exhausted air also passing through the heat exchanger, could reduce the energy loss. Commercial energy recovery systems are available but are probably too expensive and limited in capacity to be viable. Such a device could probably be shop built but I am not sure I would be up for such a challenge. Alternatively, the exhausted air could be filtered and returned to the shop. This method would reduce energy loss, but requires air filtration, some extra space, and filter maintenance.

View Bill7255's profile

Bill7255

414 posts in 2121 days


#6 posted 12-04-2016 01:09 PM

IMO it is really how your shop is designed and what your heating source is will be a significant factor in how effective it is to vent outside. When I built my new shop (30’ X 50’ with 12’ ceiling), I wanted three major improvements over my old shop. Being able to heat 24/7, a bathroom, and vent outside. For heating I choose in floor hot water. My previous shop was overhead propane. For venting a DC outside it would be important to heat 24/7 because venting would displace the inside air, however it would not displace the heat stored in the tools and structure. To vent outside I knew I would need make up air. I put gable vents in the overhang the full length both sides and up to the peaks. I did not want a ridge vent. I insulated the roof rafters and put in my drop ceiling just below the gable vents that have sufficient openings into the shop. So my make up air is from the gable vents mixed with the air above the drop ceiling before coming into the shop. I can run my DC for hours and not really see any change in temperature and little effect on my heating cost. I do not AC my shop, so I don’t how venting outside affects AC temperature of cost. So I believe shop design and heat source are big factors in venting outside. The benefits are great. No filters to clean and same performance without a drop due to filters plugging.

-- Bill R

View Redoak49's profile

Redoak49

2894 posts in 1825 days


#7 posted 12-04-2016 01:59 PM

Another issue to consider is humidity. In the winter, you would be pulling cold air in and when you heat it up the relative humidity will be very low.

In the summer, pulling in air with high moisture content could result in rust issues.

Of course, where you live will make a huge difference. Living in northern Indiana, this can be a problem. If you live in a very dry area, it probably does not make much of a difference.

View Holbs's profile

Holbs

1722 posts in 1865 days


#8 posted 12-05-2016 12:51 AM

Let’s do a simple experiment. When it’s freezing cold outside, put in a window fan in bedroom blowing outwards. Let us know the results :)

-- The Carpenter Bee is derived from the Ancient Greek word wood-cutter

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