Cyclone Venting Outside - Small Shop - What do you think about heat loss!

[Ken Frohnert]

I am thinking about getting a small cyclone (mini-gorilla) for my 12x20 heating shop area and venting the residual dust outside. I live in the boonies so there is no neighbors to worry about; unless it is deer, black bear, and fox. I figure I will not have to worry about filters plugging and losing airflow. I figure it will also save space in the shop area since there will be no filter. I need something for my lathe and table saw. I will probably run my miter saw and router with a vac. The downside question for external vent - is I work on the lathe for a decent while at a time and I wonder how cold my shop will get in the winter - I have electric baseboard heat so I don't have a downdraft fume issue. What has your experience been on external venting? Any other suggestions or tricks?

[fRED mCnEILL]

I hazve the same setup except my dust collector exits into the chip shed(chips and sawdust are for the horses)
When I run it for a while there is no doubt it cools off BUT we live in a farily mild cimate (Vancouver B.C.)and the temp rarely gets below freezing so its not too much of a problem.

[Kent A Bathurst]

12 x 20 with 8' ceilings = 1,920 cu ft. The mini gorilla shows 600 CFM.

There might be other factors at play, but that says you'll exchange the air in your shop every 1920/600 = 3.2 minutes. About 19 times per hour.

Ya reckon your baseboard heaters will keep up with that number or not? You don't say where the makeup air will come from - the connected main heated house, or the outside of a standalone shop.

If you're bringing in 32*F makeup air, and exchanging the air in your shop 19 times per hour, I'd bet you'll notice it a fair amount - in shop temp and in elect bill.

[ian maybury]

My sense is that how much of an issue it might be is pretty highly dependent on the CFM of your system, and also on for how long you run it. Depending on the structure of your workshop there's also the possibility that the fabric of the building can act as a pretty large heat sink, and greatly slow any temperature drop too.

Disregarding any change in specific humidity (air conditioning), the basic formula is heating load in Btu/hr = 1.08 x CFM x delta T. Delta T being the change in air temperature in deg F. (up or down) 3412Btu/hr = 1kw.

The numbers can seem spectacularly large if you run the above formula, and treat it as a continuous heating load. Depending on how you do the maths on intermittently running the dust system the picture can i think look very different though....

Dust is the other issue. Even when regulations prevent exhausting outside there's still the option to run a cyclone or other dust separation device, and if that's not enough to possibly add a very coarse bag filter outside. Just how much filtration is needed depends I suppose on the letter of the law....

ian

[Eduard Nemirovsky]

Have same question about year ago - convert to venting outside and in 3 mo put filter in my shop back. To much heat or cold ( depend on time of the year) to loose. Need to keep door ajar or windows open for intake.
Now with good filters and cyclone in soundproof box - I am happy as can be.
Ed.

[ray hampton]

If you vent into the prevailing wind, will the wind push the dust back up the pipe into you shop ?

[Ken Frohnert]

Kent - I have a stand alone shop.

Ray - I will vent on the east side so I will be with the wind in most cases so there will be no blow back issues.

I am concerned about the micro dust and am really trying to figure a workable (cost and space) plan that will hold the dust down. The lathe is my biggest concern. I recently purchased a NOVA 1624 so it is a mid sized lathe. My table saw has never really been a huge dust creator - it is an older Delta Unisaw. Here in PA we get a fair number of sub 32 degree days in January and Feb. I really don't know the best option for me - may be there is really no good option but just less than optimal solutions.

Do you guys think venting outside is not the best alternative? That I should just run a hepa filter on the mini-gorilla?

[ray hampton]

the HEPA filter will be better during the cold months but I would vent to the outside when the spring-fall, how will you keep birds or animals out of the pipe ?

[Chris Rosenberger]

Dust collectors generate heat that helps heat your shop in the winter. Venting it outside is not only costing you money for the furnace heat you are blowing out side, but also the free heat you would be getting from the dust collector running.
As others have said, you will also have a lot of cold air coming into the shop through the cyclone when it is not running.

[Myk Rian]

Do you guys think venting outside is not the best alternative? That I should just run a hepa filter on the mini-gorilla?

That's my opinion.

[David Micalizzi]

It's a bad Idea! The money you would be sending to the Electric Company for heat would buy you many good filters. I understand your concern about fine dust though and just wanting to send it outside. Not practical in cold or hot climate though. Buy a good filter and be done with it.

[Paul Cahill]

I agree with Ian, don't discount the thermal inertia of the building and its contents.

I discharge directly outside and and am pleased with the setup. I am in in south Tennessee, and heat loss may be more of an issue for those in more northern climates. The first iteration of my DC system had the filter inside, but my air flow was very low for a number of reasons. I did a complete revamp, eliminating all the flow resistances that were obvious. I can't give you numbers on the contribution of each bottleneck that I removed, but I got my CFM way up. I have great intentions of posting my flow measurements at some point, but aside from the CFM flow which I dramatically improved I noticed two other benefits of direct discharge: lower noise and elimination of odor from the filters. I don't know if the odor from the filters would have been measurable on my Dylos, but it was noticeable and I was very pleased to eliminate it.
In the end, even though I spend a lot of time in the shop, I don't need to run the cyclone that much, and the net heat loss is not measurable.

Not a definitive answer to the original OP, but my impressions for what they are worth.

Paul

[Alan Schaffter]

I'll be a bit contrary here on two issues-

First, I don't think the mini-Gorilla is the system for you. It is a portable system designed to be connected via a hose to one machine at a time. It is not designed to be used in a fixed, ducted system.

Second, discharging outside results in the best CFM, best dust collection at the source. Unless you run the DC continuously the heat loss will not be as bad as you might think. Examine how you use the machines you will add dust collection to- do you make a cut or two in a few minutes then spend a half hour doing another chore, or do you spend hours sawing, etc. If you use machines for only a few minutes at a time, there is no need to keep running the DC. You will not be heating the entire air volume of the shop many times over to normal shop temp when running the DC- you will not be using any more energy than you would otherwise running the heater continuously, for the time the DC is on. Unless you run the DC continuously the shop will reheat the final volume of air fairly quickly because of its thermal mass. Without going into the math, the thermal mass of your shop floor, walls, ceiling, and contents is over 1000 times the thermal mass of the air it contains!! Sure it will cost more, but again if you use the DC only when you need it, it won't be nearly as bad as you think.

[Ken Frohnert]

My shop is only 12x20 so I plan to use the dust collector one machine at a time. My shop is so small I have to move my TS out to use it so I figure I will just hook the DC up to the machine that I currently have in use. Plus the Mini-Gorilla as the smallest foot print which is key for my small shop. I am no DC expert so perhaps there is another choice that is better but will not take significantly more space-if so please advise. I am not dead set on the Mini-Gorilla just liked the small size.

I don't run the Tablesaw for long but I tend to turn for a good number of minutes at a time. So that may lead to more cool down.

However, I guess I could use the HEPA filter in the winter and then maybe in the spring/summer/fall attach a flex hose in place of the HEPA filter and just stick the hose out the window and vent away. I could probably make a little plywood spacer that would fit under the window with a cut out just big enough to hold the hose; and close the double hung window down on the plywood. That way there would be less dust coming back in the window. If I could do that - then for 3 seasons I could externally vent and for 4 months I use the HEPA filter so as not to blow my heat out. The other advantage is no hole in the shop wall.

[ian maybury]

The problem with this like in the case of many dust system issues is that while there's pros and cons at the level of principles it can be tough to get to a specific answer to suit your situation.

It's possible to run some basic maths that'll show the big picture, but there's always the possibility of detail issues like draughts, very cold weather, need to control humidity and the like that'll catch you out.

Many of us have built dust systems which can both exhaust outside, or recirculate through a filter. It's generally not that complex to organise (just a blast gate and some ducting), and it creates the option to play it by ear.

If money is tight you could build it to exhaust, but leave provision to easily install a filter to which you could if needed recirculate in future...

ian