Dale or Bill...vent question please

[FlameDancer]

Here are some pictures of my ventilation system. It is a wall mount range and it pulls 600 cfm's. I take the filters out though, to give more pull. I read this somewhere but anyways...I did the incense test and the smoke pulls directly out and you can't even smell it in the room. This is vented in my attic and sits on top of the soffice? soffit? (I believe that is what it's called) and goes to the outside but there is no "hole" that it fits through. I hope I am making sense here. Now, since I JUST found out what a baffle is, do I need one here?

Thanks for taking a peek and any help you can give me.

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[Dale M.]

mmm... No exit hole for exhaust???.... Leads me to believe it is just dumping into attic space... IF this is situation it could lead to contaminated gasses being drawn in from attic space and contaminating the whole house air. I would like to see a visible direct vent to outside if it were mine... IF it remains in attic space then you slowly build up dangerous gasses over time of torch operation and you may be endangering your self when you feel you are safe if this air is drawn back into worke space ( or rest of house) Direct venting outside causes the exhaust gases to be diluted by out side air. This process usually drops danger to almost nil a short distance from exhaust outlet.

As for baffles?.. Yes they could improve efficiency, but they may not be necessary. 600CFM is usually a decent draw for most hood arrangements. IF you do smoke tests (similar to incense test) and you find that all the smoke is being drawn into hood and evacuated for work area, you are probably good in ventilation dept.

Smoke test is where you take a bit of paper and twist it into a small "twig" and light it and snuff it out but let it smolder... And move it around area where torch is and all the smoke is drawn into hood... Torch MUST be lit when doing test.

Dale

[FlameDancer]

Hi Dale. Okay, I knew I probably wasn't making sense when I was trying to explain it. The hood is vented, up through the attic, hose creeping along the attic floor, about 6 ft. and sits on top of the soffit (I think that's what it's called) which is basically the screen that goes around the whole house where the roof meets the sides of the house. The hose sits, so that it spills to the outside, but it has to go through that screen first. I can't cut a hole in it to just lay the hose out there. When youstand on my front porch, you can here the fan running. Should I put some sort of insulation around the base of it? Would that keep anything from coming back in? I could probably snap a pic for you to show you what I mean.

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[Heather/Ericaceae]

Hi - I'm not a venting expert but this is what I would worry about for the soffit-venting. First, it would be the same as a screen in that it would cut down on your airflow. However, from your description it sounds like you have pretty good suction. The other worry is what Dale was talking about - contaminated air getting into your attic. Check to make sure that you have excellent air seals where the duct enters your attic space, and especially where the duct is venting out the soffits. IE if you've just got the end of the duct sitting over the soffit, you should probably seal it down with something so that air can only escape to the outside. You might also want to cover the soffits to either side of the duct to prevent the exhuasted air from flowing back into the attic once it's been vented outside. If you upgrade the seals, do the incense check again in your studio. If you've made sure that no bad air is staying in your attic and your hood is pulling enough air, then you're probably okay. :) Nice looking hood, by the way! -Heather

[Mr. Smiley]

I agree, you are probably just venting that bad air up into your attic. Very little is going through the soffit. If you cut a hole and install an exit point, you'll be good. ;) If you just butt the tube up to the soffit, you're only moving as much air as can squeaze through the little holes. Prolly not enough.

[Dale M.]

I have to agree with MR "S" here ...

Your exhaust air need to be directed outside!... Into attic will just contaminate attic space with heavy metals that settle out of exhaust and make whole attic toxic... Get the outside where dilution and decomposition will work their magic to make them harmless.

Dale

[FlameDancer]

Thanks everyone:) Okay, here's what I did. There was a window, in the attic about 2 ft. up from where the vent hose was laying. What I did was extend the hose up 2 ft. and put a vent trap on the end of it and fit it out the window between the outside and the screen. Then I covered insulation with like 10 layers of saran wrap and put it on both side of the trap. The window only has to be open about 6 inches and it's setting down on the trap, holding it in place. Then I took duck tape and taped the stew out of it and calked any little holes I saw. Now, I just have to watch it when it rains to see if it will leak at all. How'd I do?

[FlameDancer]

Oh and by the way...you guys are GREAT:) Thanks so much for all the help!