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Smoke Detector Going Off During Firing


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The short story is that the smoke detector at the top of the stairs on the second floor kept going off yesterday during my glaze firing.  The kiln is in the garage (one floor down and a few rooms over).  It's an electric kiln, this was my 5th firing, my second glaze firing (cone 6).  It's an L&L with one of their downdraft vents.

 

More information: It was cool yesterday (mid 40's or so), so this was the first firing I tried with the garage door closed.  When the detector first went off, I unplugged it, opened the garage door, and then set it back up.  After a while I closed the garage door; a while later the smoke detector was going off again.  I repeated that experiment once more; same results.  

 

After the kiln shut off and was cooling down, I still couldn't plug in the smoke detector without it going off.  Which I took as a sign that it couldn't be the wiring -- the kiln wasn't drawing power any more.  

 

My first thought, then, was that the venting isn't working well enough.  L&L doesn't drill holes in the lids, relying on air getting in through the cracks.  I tried (when I first set it up) to see that using a smoking piece of paper, but it was very hard to detect any smoke entering the kiln.  If I open a peephole, the smoke gets pulled right in, so there is definitely adequate suction.  I contacted L&L about it; they basically said not to worry, that air was getting pulled out of the kiln, so it was coming in from somewhere.

 

And it got more complicated this morning when I plugged the smoke detector back in, and it still kept going off -- the kiln was down to about 480 degrees by then.  

 

So now I am thinking I have a fried smoke detector.  Maybe it's coincidence.  Or maybe my house is on fire, and I just can't tell yet (I'll let you know).

 

It is also worth noting that there are a number of other smoke detectors in the house; none of them made a peep.  The carbon monoxide detector is in the basement (where all the gas appliances are); it reads zero ppm.  

 

There is nothing funny in my glazes or my kiln; I'm using various recipes from "Mastering Cone 6 Glazes" and my only coloring oxides are cobalt carbonate, copper carbonate, red iron oxide, and rutile.  One piece has a small amount of Mason "Best Black" stain brushed on it, for full disclosure.  

 

Currently I am thinking I should replace the detector and see what happens next time.  I'd prefer to be able to fire with the garage door closed when it gets colder -- makes more sense heating-wise, and also we once had a skunk in the garage when we accidentally left the door open after dark (shut it in there without noticing -- not the disaster it could have been, but not pretty).

 

Sorry for the extra-long post, and thanks in advance for any advice.

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If the kiln is down to 480, there's definitely not any fumes coming out. This was probably all coincidence, and you've got a dead smoke detector. If you find that you're smelling fumes during the firing, go ahead and put one 3/16" hole in the lid. Sometimes the small kilns are so tight that they don't get great air flow. You can also adjust the sliding damper on the vent collection box under the kiln. Usually at 1/2 open it works fine, but you could close it down 1/16" at a time and see if that helps.

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Thanks.  I meant to mention that the damper on the vent is completely closed.  I don't smell anything during the firing.  And the "all a coincidence" idea is very appealing.  It will be a while before the next firing, but I guess I'll find out then.

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Make sure your damper isn't completely closed. You want your damper open some otherwise your pumping very hot air into your duct work and that metal pipe is gonna get hot hot hot. I don't know how effectively sealed your box under your L&L is, and I know it is sucking in air around the cracks and stuff, but I would still crack the damper some to get some room temp air in there to cool that kiln air.

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Okay, thanks.  But now I don't know how to gauge how much to open it, since I can't see smoke entering through the cracks between the lid and the kiln and between the kiln sections.  I'm considering following Neil's suggestion to drill a 3/16" hole in the lid -- that way I will easily be able to gauge how much to open the damper with a match or a smoking piece of paper.  (I'm thinking I would drill it off to the side, on the side away from the thermocouples, maybe 4 or 5 inches in from the wall -- sound reasonable?)  But before I do, here is the reply I got from L&L when I asked about drilling holes:

 

 

It can be pretty hard to identify significant airflow from outside the kiln as it comes in small amounts from all of the cracks and holes in the kiln. Really the point is just to remove all of the fumes from inside the kiln which should still be happening. Increasing airflow with additional holes generally just increases the volume of cold air entering the kiln which doesn't help you.

 

I would recommend not adding any other holes. The air brought in naturally is generally enough. I have only encountered a couple of people whose work required a ton of oxygen to react properly and added holes.

 

If I follow that advice, and don't drill a hole in the lid, what would you say -- damper half open or maybe a little less, and if I don't smell anything, call it good enough?  (And would I really smell it if it wasn't venting?)

 

Also, for the record, 43% of the reviews of my smoke detector on Amazon were 1 star, and almost all of those complained of false alarms.  So I'm ready to call it a faulty detector.  I can't completely believe the total coincidence theory, but the smoke detector is hardwired, and I saw one suggestion that fluctuations in voltage could set it off.  I can believe that firing the kiln could influence the voltage to other circuits in the house in a small way, and maybe that was enough to set it off.  (It's definitely good and fried now -- can't hook it up without it going off.)

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I drilled holes in my kiln. Easy 18-3. However I was working with an extremely dark body. I adjust damper constantly depending on my body. The other day even with two holes in my kiln, I forgot I had lowered the draw and I was using a dark body in a firing. I went into my studio and the smell about knocked me over. I increased draw slightly and smell went away almost instantly.

It's debatable if you need a hole or not, but you definitely need to open the damper to allow air in. Otherwise it could be a fire hazard with the metal piping getting hot.

I would open it about 1/4-1/2 way from closed and check the temp of the duct.

If it's cool to touch and there's no smells I would say you might be okay. But the other experts will chime in about this decision. I am not sure if you can base it off smell alone.

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