MochiFriend

Thank you Bill as always for your helpful insight. We're reaching the end of the firing now, but I am looking forward to pulling the graph from my monitor for the day that shows the TVOC levels. PM2.5 levels did not go above 1 both in the kiln room and the house. However, TVOC levels in the kiln room started increasing significantly around the 1800F mark til now (firing to cone 5 - 2150F ish) — they started spiking from 500 ug/m^3 and are now at 2313 ug/m^3 in the kiln room. Indeed it is a helpful reminder of what you said, fumes are not going to be 100% covered by downdraft ventilation and even if like 90% of the fumes are captured, the small % of fumes that are not captured are still pretty bad. Also, I cannot smell anything in the room, but it's a good reminder that smell != fumes as sometimes we can't smell the latter. For example, when Skutt says "little to no smells/fumes will leak out of the kiln" — even a small amount of fumes is significant, imo. That all said, I've decided that for my own peace of mind I will be relocating the kiln, ideally now to the garage (but this will be determined by if we can get a 240volt outlet routed down there, which will be challenging - contractors coming to quote this week). Another conclusion I've come to from this whole experience is that I also don't think kilns, even small kilns, are suitable to fire in the home.

A follow up! There's a smell in the kiln room (above + around the kiln), but no smell in the adjacent office room. Readings: 500F: TVOC Baseline: 0 in all rooms Living room: 0 Kiln room: 23 ug/m^3 PM2.5 Baseline: 1 in all rooms Living room: 1 Kiln room: 1 1200F TVOC Living room: 120 Kiln room: 320 We are wondering if we should perhaps close the door to the small kiln room so that the only negative air intake is instead from the leaks around the house. I'm not sure if this would make it spread more or less given that the fan is not venting out all the fumes. (Our stove is electric and furnace intake is from around the house - not near the kiln room). I think that given there is still the persistent smell in the kiln room even with the additional fan venting out -- I am considering to move the kiln to be right in the corner between the two windows (health is first..).

When you run the dryer it exhausts 200 cfm, window open or not, so no, air will be drawn in from the many minor openings in the house. Opening the window even a very small amount will help ensure that you do not suck fumes back down the flue of a gas fired appliance though. Most old codes allow exhaust by volume …. if there is sufficient home volume to draw from. Most homes have leakage on the order of 5 air charges per hour or more. Thank you Bill, that is good to know. So just to clarify, is your answer / advice that "yes we should leave the window in the adjacent room open slightly" to ensure that the fumes aren't sent back around thru any gas appliances? Since there are two windows in the adjacent room, one of the windows has the new fan venting out of it, and I've propped the other window open slightly. I've seen advice on this forum to always ensure that there is a nearby window open to provide air intake source near the kiln when a vent is being used, so am somewhat confused about this advice if that is the case (because wouldn't the same principle apply, that you would just have the air being drawn from the cracks and crevices around the house?). Kiln is firing and the PM 2.5 reader is positioned in the upstairs living space, eager to see what the readings show today. Thank you!

Hello everyone, I just wanted to give an update and say thanks for the advice so far. I've set up the additional venting to match the exact diagram that @Bill Kielb sent over in his latest message. I'm going to do a glaze fire tomorrow and have a pm 2.5 + voc reader in the room to monitor. I'm curious if you guys think that having the one window open is necessary for intake airflow. I understand that the two outflow vents require a source of intake air, however would the intake air come from around the house as the room is not a perfect vacuum? Anyway, I will be leaving the window open as planned for now, but this is something that my partner and I debated about. Many thanks.

Amazing thank you! It turns out that my partner has a fan for this purpose already, he uses it with his laser cutter (which is also why we have a piece of wood with a circle cut out for our window). So all I need to do is just get some ducting from Home Depot. Do you recommend attaching any kind of "capture device" on the end of the duct that is in the kiln room, eg. some kind of lightweight hood or umbrella-looking thing? Or just the end of the tube sitting there near the kiln is fine for the purposes of testing this out? Best, Ali

thank you!! this looks great!

Hi @Bill Kielb and @neilestrick, thank you both so very much for your thoughts!! I will attempt to use this fan on my next glaze firing. Do you think it would be less effective if: 1) I did not mount the fan to the wall, instead securing it to a shelf adjacent to the kiln — and 2) also ran ducting from the fan out one of the two windows in the nearby room? (I have a cover that can cover the entirety of the window except for a hole for the vent). Below is a diagram illustrating this. The reason why is because I'd like a quick, low-commitment way to test this fan option without putting multiple holes in drywall + my external wall. Totally get that this is just part of having infrastructure to support a kiln, but another option I am considering is moving the kiln into the office room to be between the two windows. This is a much larger endeavor, as we'd have to swap rooms in the house and move a lot of things around, so I want to test out the fan option first in an easy way. If it does seem effective, then I could commit to installing it w/ proper venting and such. Below is a diagram of the potential new kiln placement. I believe this would be better(?) as the two windows naturally would create a negative pressure situation around the kiln, though it might be more annoying to have the kiln right next to the window — perhaps that might affect the firing? As always, I really appreciate your time and insights. Thank you!

Ah, you raise some very good and logical points. For this fan - which is similar to Bill's bathroom fan idea, thanks for the link! - two quick questions: 1) Could I potentially install the fan in the wall, then connect the duct to the duct on my kiln vent (between the Envirovent motor and the hole in the wall)? Essentially I'm trying to limit the number of holes I drill on the external wall of my house, lol. Crazy idea? 2) In your experience, does this fan hold up to the 35db noise estimate that it's marketed as? Just trying to be considerate to neighbors on the other side of the fence. I really appreciate this advice. Is it somewhat contradictory to create a hole in the lid as a start, and then to try to plug up one of the lid holes as a follow-up experiment? Plus, if the issue is that the vent is not drawing enough air thru the bottom wouldn't the former (creating an additional hole in the top) exacerbate the problem because more of the warm air would escape thru the lid? Thanks very much. I've read a lot of these forums as a lurker and have learned quite a lot from your past advice too. Hope you are all having a nice weekend~!

O Got it. I did just check and the Skutt Envirovent is 140cfm (https://skutt.com/images/11.18-EnviroVent-2-Specifications.pdf). However I've turned off the box fan anyway. Will look into ducting / fan via the crawl space! I also just want to exhaust (haha get it?) all other options as well since I'll coordinate with our handyman in for that, hence why I'm curious about the kiln hole size possibility. Thanks Bill, really appreciate your taking the time out of your evening to trouble shoot all of this too!

OMG, I just went downstairs to turn off one of the 2 box fans, and @Bill Kielb, your suggestions seem to have made a change. THANK YOU! 1) The office room smelled (understandably) like trash because the kiln room's smelliness was being sucked out via the fans. Now it smells like nice clean outside air. 2) The kiln room actually seems to smell better. I'm now in the last hour of my firing (~1800F), so obviously the smelliest part passed 8 hours ago, but there still was a lot of lingering smell from before. I'm interested to see if my glaze firing next Friday has a difference, and I'll also incorporate measurements from a particle reader here. I'll also call Skutt next week to get their advice on widening the bottom kiln hole a bit. I hope that this thread doesn't get archived in the next week. I might be not understanding the whole concept of pressurization, but to my understanding some people have their kilns indoors next to a giant sliding door, outside in a shed, outside under an awning, etc. Isn't that a lot more pressurization on the kiln itself (thus perhaps affecting the firing schedule even?) than a box fan that's like 7 ft away, pointed 90 degrees away at the adjacent wall? I APPRECIATE YOU GUYS!!!

I'm understanding now what you mean by airflow/pressure — the suction framing is very helpful. I need to make sure the air is going generally towards the kiln because that's where the exhaust is (such that the air's flow is then thru the vent). Under this suction principle, I totally get that it would be best to have some kind of exhaust fan in that corner of the kiln room, however that is actually where a door to the basement is. (The basement isn't a super great option — it's directly below my bedroom, and the floor is uneven because where I live is quite hilly. It's basically the unfinished crawlspace/storage under the house). I've illustrated this in my diagram. I really appreciate this idea. I will remove the closest box fan blowing into the kiln room. The other one is helpful I think to still have in the office for the purposes of "suction." The kiln room is three stair steps elevated from the office and there's a lot of random stuff in both rooms that therefore blunts the directness of the box fan's wind.

Ah, I see. Do you think it would be better to just not have the box fans going at all? I will definitely look into getting a bath fan installed in that room. On the topic of the kiln vent's exhaust strength, do you think there's any merit behind the idea of widening the kiln's bottom outtake hole more? It's currently 3/16. I saw a similar thread where the poster increased their hole, presumably from around that size to 5/16 and they noted it made a difference. (https://community.ceramicartsdaily.org/topic/23314-vent-fan-still-allows-fumes/page/2/#comments) Thank you, thank you!! I'm so glad I posted here.

Oh, I see haha. That's a neat idea but unfortunately I can't run the dryer at the same time — my kiln plugs into my 240v dryer outlet (it's the Skutt 818-3, which is adapted for this usage). Dryer is also on its separate venting system.

Got it (btw I responded to your message in the above message, but I'm new to the forums so not sure if I have to "quote" you for it to thread properly). Thank you. I've turned the fans in the office/kiln rooms to be facing IN towards the kiln room to create the negative pressure... we'll see if that helps! (though it'll be hard to tell at this point since I'm at the end of my bisque firing, but will observe for the subsequent glaze firing) Before, I had turned the fans OUT of the kiln room to create a positive pressure path from the kiln room thru the office room and out the window. I figured if the fumes are going to hang out, I'd rather them follow my directed path out than float around indiscriminately my house. Regarding this last part of your message, my kiln is super small (Skutt 818 is about 2.5 cu). When you write, " You could test your next firing with it running to see if that will be sufficient exhaust", what do you mean by "it¨ — the existing kiln vent? Or the fans pointed in to the room? (At this point, the fans are pointed in towards the room so they are no longer exhausting the room. I have however not pointed the fan directly at the kiln to avoid messing with the firing). Thank you!!! Literally at my wit's end so this is all helpful.

Hi Bill, Ah, I see. So with the principle of the kiln room being lower pressure than other rooms in the house — I currently have the door to the adjacent office room open, as well as two windows in that office open. I have two box fans directing the air away from the kiln room and into the office room. My reasoning was that because the kiln room is smelly, I want to try to direct the smell in the air out of that room and towards the windows in the adjacent office. So currently: kiln room -> fans pointed towards -> office room -> windows Does that principle of the kiln room being lower pressure mean that I should instead be trying to bring the outside air into the kiln room from the adjacent office room? So: office w/ windows -> fans pointed into -> kiln room (and then ideally it gets sucked thru the kiln -> out thru the vent)? I have tried to illustrate this in my attached diagram. I'm not sure if I'm overthinking this but the vent seems to be struggling to pick up all the fumes so that's why I thought I had to "help it out" by airing out the rest of the room myself. Thanks very much for your thoughts and input into this. It's really helpful.