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Thread: Need Suggestions on Ventilation and DC

  1. #1

    Need Suggestions on Ventilation and DC

    Working on improving dust collection at the source. Added a SDD Cyclone w/outside exhaust and overarm to my TS. With the SDD no bag inflating every time I turn on the DC. Also working on improving ventilation, which is difficult in my shop.

    Next steps: move the Jet scrubber to location in red and add a 12" exhaust fan (also in red) to the west window. The west window was closed off when I installed the SDD but there's enough space to add the fan. My windows are down one end and I hope moving the scrubber will pull the dead air to the new fan.

    I am aware of the carbon monoxide risk with negative pressure..... I've tried to mitigate risk by sealing off the floor joist cavities and caulking pipes between the shop and storage area. I also installed a door sweep and weather strip on the shop door. I also open the north wall window 6" (fully opened in summer) whenever I run the SDD.

    Should I be concerned about carbon monoxide adding the new 12" exhaust fan which will cause additional negative pressure? ....even with the window open 6"?

    Do you think my next steps make sense? Any suggestions?

    Shop_Above.jpg
    Last edited by fred everett; 02-11-2021 at 12:57 PM. Reason: spelling
    Thanks,
    Fred

    Seasoned professional possessing unremarkable proficiency at innumerable skills.

  2. #2
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    A suggestion and a question. Suggest you add a CO detector if you have concerns. Question, where does the combustion air for your furnace and hot water heater come from? Do they have an outside air source?

  3. #3
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    add a gravity damper to an outside wall so that if the area goes negative then it opens as much as needed to make the air up. too much exhaust not to have something letting air in
    Ron

  4. #4
    Quote Originally Posted by Doug Garson View Post
    A suggestion and a question. Suggest you add a CO detector if you have concerns. Question, where does the combustion air for your furnace and hot water heater come from? Do they have an outside air source?
    Quote Originally Posted by Ron Selzer View Post
    add a gravity damper to an outside wall so that if the area goes negative then it opens as much as needed to make the air up. too much exhaust not to have something letting air in
    Ron
    My furnace and hot water heater are atmospherically vented in a 14' x 20' space. An unvented basement door has a 1" bottom gap where a significant stream of air flows through when the furnace runs. There is no outside air source. The code formula says the space doesn't provide the required combustion air.....which frankly surprised me for such a large space.

    I ordered a CO detector and testing tool. In the interim I did a rudimentary smoke test for backdraft. Both furnace and hot water heater pull smoke the same with the cyclone on or off in the shop......that's with the shop window closed. I don't seem to have a backdraft issue, so I theory I shouldn't have a CO issue. When the tester arrives I know for sure.

    Right now I'm trying to figure out if I can add louvers to the basement door. I also have a couple 2" holes (currently plugged) in the foundation that where used to the previously furnace which was high efficiency. I'd rather not drill the foundation but those hole are prob too small.

    I feel like we're far into HVAC territory.......but this may be a valuable discussion as many of us have powerful DC systems and ventilation challenges.
    Thanks,
    Fred

    Seasoned professional possessing unremarkable proficiency at innumerable skills.

  5. #5
    I get 0 PPM using Klein Tools ET110 CO Meter with the furnace\hot water running while the DC is running, and the window closed in the shop. At this point I don't have a backdraft issue. I plan to move the scrubber and install the fan as planned.....and additional CO testing when complete.
    Thanks,
    Fred

    Seasoned professional possessing unremarkable proficiency at innumerable skills.

  6. #6
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    Hi Fred, when does the wall fan operate? Also, where is the basement door with louvers?

  7. #7
    Quote Originally Posted by Michael W. Clark View Post
    Hi Fred, when does the wall fan operate? Also, where is the basement door with louvers?
    The fan (not currently installed) will be in the shop and used during wood working. I don't currently have a louvered door......at this point I'd only install one if I have a CO issue after installing the fan in the shop.
    Thanks,
    Fred

    Seasoned professional possessing unremarkable proficiency at innumerable skills.

  8. #8
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    Sounds like you are approaching this in a sound thoughtful manner. My gut feel is you should add an outside combustion air source for the furnace and hot water heater but your monitoring of CO as you proceed with changes will determine if my gut is right.

  9. #9
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    Quote Originally Posted by fred everett View Post
    The fan (not currently installed) will be in the shop and used during wood working. I don't currently have a louvered door......at this point I'd only install one if I have a CO issue after installing the fan in the shop.
    Just keep the two areas isolated from each other. I assume at top of the stairs goes into the house? Is that the door with 1” gap at bottom? You could always add louvers in that door.

    Still not sure I understand the intent for the 12” fan. Are you spraying finishes or are you sensitive to the woods you are working with? Your DC is venting outside and you are drawing in outside air. Will the 12” fan run at same time as DC? If so, will need more outside air. The wall fan is low SP so it is easy to starve. With your CO monitor/detector, you can open the window more if needed.

  10. #10
    Quote Originally Posted by Doug Garson View Post
    Sounds like you are approaching this in a sound thoughtful manner. My gut feel is you should add an outside combustion air source for the furnace and hot water heater but your monitoring of CO as you proceed with changes will determine if my gut is right.
    I do NOT want make a mistake with carbon monoxide. After researching these systems I share your concern so I also installed new First Alert and Kidde CO detectors (disparate detectors by design) near the systems to provide 2 levels of monitoring. Not to go IT geek, but the Klein tester and co detectors give me 3 levels of data, but no root cause regarding why I DO NOT have a problem. I can only assume my maniacal approach to sealing off the shop has left the negative pressure air replacement pulling from outside above the block foundation, and/or from the second level between the floor joints. I guess I could rent an infrared temp tester, which would likely provide an answer to that speculation.

    At any rate I've yet to install the exhaust fan on the shop side....once that is done I'll test again and provide an update in case anyone else is reading. Maybe this will save a life who knows.

    Quote Originally Posted by Michael W. Clark View Post
    Just keep the two areas isolated from each other. I assume at top of the stairs goes into the house? Is that the door with 1” gap at bottom? You could always add louvers in that door.

    Still not sure I understand the intent for the 12” fan. Are you spraying finishes or are you sensitive to the woods you are working with? Your DC is venting outside and you are drawing in outside air. Will the 12” fan run at same time as DC? If so, will need more outside air. The wall fan is low SP so it is easy to starve. With your CO monitor/detector, you can open the window more if needed.
    Correct, door is at the top of the stairs. Louvers is step 1 in the plan to mitigate if I have an issue post install of shop side exhaust fan.

    The fan will be used as an exhaust for solvent and finish fumes (non spray) along with smoke from torches and wood dust. The illustration shows I have a single openable window down one end of a 28' shop which to me is not ideal. I wear a respirator 100% of the time I'm in there but I want as must dust out of there as possible. It's likely the fan will run when I'm in the shop for 8-9 months out of the year temp permitting.....with the window fully open. During the other months likely only to help remove fumes.
    Last edited by fred everett; 02-16-2021 at 10:33 AM.
    Thanks,
    Fred

    Seasoned professional possessing unremarkable proficiency at innumerable skills.

  11. #11
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    Hi Fred,
    First, I would isolate the two areas as much as possible, sounds like you have done that to a large extent. Your appliances (water heater and furnace) will likely draw all their air from the living space through the door at top of stairs. You wouldn't get any CO coming back from the exhaust unless the storage room was under negative pressure such that the gasses would come back in the house instead of flowing out. Keeping the areas isolated should solve this concern but the CO monitor/detector is still a great idea.

    For the shop fan, if your fumes are flammable, be careful. I'm envisioning you have a fan with the motor direct mounted to the wheel so that the motor is in the airstream. If the concentration is high enough, that is not good unless you have an XP motor. You may consider mounting the fan to pull outside air into your shop, this would put the fan always in fresh air. The downside is you would need to deal with the blast of air so it doesn't stir up dust, a real problem when finishing. If you are doing waterbase, probably not much of an issue with the fan.

    Put your overhead filter and exhaust fan close to where the dust and fumes are generated. For example, if your dust is generated near the window by the door, then put the overhead filter in that area. If you put it in the opposite end of the shop, it has to pull dusty air all the way back there to filter it. No need to get dusty air in the rest of the shop when you can filter it closer to the source.

    I have struggled with a home setup for finishing that is easy to setup and keep dust away. I like to spray finishes and currently use one of the finish shelters that look like a one-sided tent. I put it in the end of the shop and try to only use it with the door open. I'll spray waterbase with the door closed on a small project but not oil-base, shellac, or laquer. You need ventilation but if finishing in the same space, the ventilation stirs up dust. For wipe-on finishes, I wait a day after I have done any dusty operations, then apply. No dusty operations till I'm through finishing.

  12. #12
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    I'm not sure if you already have the fan, but if not, I'd suggest getting an explosion proof one. Definitely pricier, but can exhaust solvents / flammable finishes safely. I've very glad I purchased one.
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  13. #13
    Quote Originally Posted by Michael W. Clark View Post
    Hi Fred,
    First, I would isolate the two areas as much as possible, sounds like you have done that to a large extent. Your appliances (water heater and furnace) will likely draw all their air from the living space through the door at top of stairs. You wouldn't get any CO coming back from the exhaust unless the storage room was under negative pressure such that the gasses would come back in the house instead of flowing out. Keeping the areas isolated should solve this concern but the CO monitor/detector is still a great idea.

    For the shop fan, if your fumes are flammable, be careful. I'm envisioning you have a fan with the motor direct mounted to the wheel so that the motor is in the airstream. If the concentration is high enough, that is not good unless you have an XP motor. You may consider mounting the fan to pull outside air into your shop, this would put the fan always in fresh air. The downside is you would need to deal with the blast of air so it doesn't stir up dust, a real problem when finishing. If you are doing waterbase, probably not much of an issue with the fan.

    Put your overhead filter and exhaust fan close to where the dust and fumes are generated. For example, if your dust is generated near the window by the door, then put the overhead filter in that area. If you put it in the opposite end of the shop, it has to pull dusty air all the way back there to filter it. No need to get dusty air in the rest of the shop when you can filter it closer to the source.

    I have struggled with a home setup for finishing that is easy to setup and keep dust away. I like to spray finishes and currently use one of the finish shelters that look like a one-sided tent. I put it in the end of the shop and try to only use it with the door open. I'll spray waterbase with the door closed on a small project but not oil-base, shellac, or laquer. You need ventilation but if finishing in the same space, the ventilation stirs up dust. For wipe-on finishes, I wait a day after I have done any dusty operations, then apply. No dusty operations till I'm through finishing.

    Quote Originally Posted by Alan Lightstone View Post
    I'm not sure if you already have the fan, but if not, I'd suggest getting an explosion proof one. Definitely pricier, but can exhaust solvents / flammable finishes safely. I've very glad I purchased one.
    Thanks Gents. I bought a std greenhouse exhaust fan. No gun or booth. At the behest of master I honed "one method that works for your style". I wet sand a BLO, MS and Varnish mix 4 coats ....400 grit to 1000. Coats get wiped dry and left overnight....rags taken outside. With windows open there's little fumes.....zero risk, no but likely close. This method does well in a dusty environment as the layers are essentially dry when completed. Dust that settles on the finish is buffed off. Result is a silk smooth finish....some yellow can wax and wow! Downside is it's not suitable for a table top or other high traffic areas.
    Thanks,
    Fred

    Seasoned professional possessing unremarkable proficiency at innumerable skills.

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