Warning: Controversal Subject, Venting DC Outside, Need Help Please

[Paul Richard]

Hi Everyone,

THANKS for alerting me to the seriousness of my considerations here, as well as the good feedback on how to go about it.

The idea I had in mind before venting outside was effectively the same as James'. I need to do some homework on how I would actually put that together, but that is likely going to be my approach.

I need to do more homework on the 6" ducting too. I have what I consider to be very good suction at the hose, but realize I should try to capture more at the source. My chop saw is the worst offender and I want to build a hood for that beast.

My sincere appreciation folks - this had more risks than I considered.

Any other thoughts or suggestions? I'm all ears.

- Paul

[Jim Andrew]

I vent outside during moderate weather, but have no water heater, and use an outside wood burner, so would not affect the heater. Also have 3 garage doors, and they let air come around the edges when you send air outside. Even with weatherstrip.

[Andrew Kertesz]

I understand the concerns about CO2, but how do you explain the thousands that do vent outside without any adverse issues?

[Larry Frank]

I do not know if CO is a potential problem or not but it could be. If it were me, I would get a CO detector with a digital readout to determine if it was a problem.

[Don Parker]

We don't know what types of heating systems those people (whoever "they" are, and however many of them there actually are) have in their shops.

if we assume there are folks who do it, you might as well ask why millions of people go without seat belts and don't get hurt, or spray nitrocellulose lacquer without an explosion proof fan and never blow up. There are people who beat the odds, I guess. Do you want to gamble with your life that you will be among them?

[Alan Lightstone]

1.) Don't vent outside. The CO hazard, as so well stated by others, is real, and quite deadly.

2.) Since your problem is with airborne dust particles, an air cleaner is your best solution. Mine isn't in an ideal location (I put it where I had open ceiling space), yet I am constantly astounded how well it cleans the air quickly (tested by my Dylos meter). I think it's been some of the best money I've ever spent in my workshop. I keep an activated charcoal first stage filter on mine, which also helps a little with organic vapors. Every bit helps.

3.) Lots of good advice on modifying your DC system for more SP and flow. I've been very happy that I'm running at least 6" pipes to my equipment. Even with that, the drum sander creates dust particles like you wouldn't believe, but the air cleaner scrubs them quite quickly.

[Robert Engel]

Paul,

Here are the correct answers LOL.......

1. Cartridge filter + Cyclone (See the setup James has in post #14)
3. Air filtration unit
4. Respirator (do NOT rely on your DC to remove suspended find particles not picked up produced by sanding, working with MDF, etc.)
5. Increase ducts to 6" you are starving your blower with 4" (there I said it!!).

[Alan Schaffter]

I understand the concerns about CO2, but how do you explain the thousands that do vent outside without any adverse issues?

It is not CO2 (carbon dioxide) that is the problem, it is CO (carbon monoxide) and it is only an issue if the shop is in a room with a wood, oil, gas, etc. fired heater or hot water heater and standard flu/chimney (not a closed system). There is still a hazard but much less if you are in a shop with a couple of large doors/windows or garage doors that can be opened to provide an adequate source of make-up air. The problem, as I posted earlier, is that you don't need high concentrations of Carbon monoxide (CO) because CO has 210 times greater affinity for hemoglobin than oxygen!! With carbon monoxide attached, hemoglobin can no longer transport oxygen

"Hemoglobin is an iron-containing oxygen transport metalloprotein in the red blood cells of most mammals. Simply put, it's a carrier protein. Interestingly it doesn't carry carbon dioxide in the same way it does for oxygen O2. Oxygen binds to the iron atoms in the protein whereas carbon dioxide CO2 is bound to the protein chains of the structure. Carbon dioxide doesn't compete with oxygen in this binding process.

However, carbon monoxide CO is a very aggressive molecule. It's a colourless, odourless, and tasteless gas that is lighter than air and can be fatal to life. It has a greater affinity for hemoglobin than oxygen does. It displaces oxygen and quickly binds, so very little oxygen is transported through the body cells."

[Peter Aeschliman]

I get the extreme caution that people are giving, and understanding this issue is seriously important.

But I would like to note the nuance Alan mentioned, which is that high efficiency gas furnaces nowadays are closed systems. The CO2 is vented outside through​ a sealed PVC pipe, and the furnace pulls fresh air from outside through another sealed PVC pipe.

CO is an issue for flu style furnaces when the furnace doesn't burn 100% of the gas, as the byproduct of fully-combusted natural gas is CO2 (not CO) and water. So if your furnace is working well, it shouldn't exhaust any CO.

That said, gas water heaters with closed intakes and exhausts are generally really expensive, so they aren't as common as high efficiency furnaces.

Long story short, there's more nuance to this discussion than some are portraying in this thread, but better safe than sorry. Don't take the risk if you aren't 100% sure about your situation.

[Alan Schaffter]

To add to what Peter said, it doesn't take much for the air/fuel mixture to be off just enough for your furnace or heaters to generate CO. Even if you have an open system, if the flu/chimney is operating normally (good up-draft, not counteracted by a running DC pulling against it) a CO detector may not detect, and you can't see or smell it, so you may never know your furnace or hot water heater is producing CO, since it is going up the flu. A DC pulling reverse flow is a different story. Just think back to how many reports of CO poisoning and deaths caused by kerosene space heaters* you hear about each winter, or school kids getting poisoned from a leaking school bus exhaust.

*"Each year, nearly 5,000 people in the United States are treated in hospital emergency rooms for CO poisoning; however, this number is believed to be an underestimate of CO poisoning because many people with CO symptoms mistake the symptoms for the flu or are misdiagnosed."

[Jim Dwight]

Unless you can seal the burners off from the shop, I agree you shouldn't duct the DC outside. DCs move a lot of air so sucking in exhaust is a real possibility. But a wall and exterior door might be able to seal off the shop from the heaters.

[Jerome Stanek]

If you have access to an outside wall how about an air to air heat exchanger

[Jim Falsetti]

Paul, per Robert's point number 3 - have you considered an air filtration unit? I have one, and it seems to help. Maybe some other members with a Dylos Particle Counter could comment on the effectiveness of an air cleaner. (I now see the Dylos answer is in Alan's post #7, point 2 - it works just fine.)

Best,
Jim

[Larry Edgerton]

I blow mine outside. I have outside intake air for my heater. No problem. Shop is cleaner, don't have to empty containers. Win/win for me. Heat bills went up about ten bucks a month. You could not pay me $10 to empty the DC 20 times a month.

But... I live in the middle of nowhere and have no neighbors. I also use it to change the air in the shop if need be, open a window and turn it on for about two minutes. Cleaning the shop? put on a dust mask, turn on the DC and take an air hose to everything, done.