clay lover Posted September 2, 2012 Report Share Posted September 2, 2012 I have been using my kiln, bought new, for 4 years and getting even cones regularly. My friend just bought the same kiln and she ordered a vent on hers. Will the firing schedule that I use without a vent produce the same results in her identicle kiln with a vent? What advice should I give her about firing ramps and rates and temps, it is her 1st kiln, that will help her get started well ? Should we expect different results from the use of the vent? overfired, underfired, less even if using the schedule that works evenly without a vent? Thanks, I am hoping to prevent a melt down here, hers, not the kiln! Link to comment Share on other sites More sharing options...
Denice Posted September 3, 2012 Report Share Posted September 3, 2012 Many things can affect your firing schedule such as how full you have it filled the number of shelves ect. I added a vent to my Skutt that I have been firing for 20years and my Paragon that I have been firing for 35 years and haven't noticed any extended firing times. Denice Link to comment Share on other sites More sharing options...
clay lover Posted September 3, 2012 Author Report Share Posted September 3, 2012 Many things can affect your firing schedule such as how full you have it filled the number of shelves ect. I added a vent to my Skutt that I have been firing for 20years and my Paragon that I have been firing for 35 years and haven't noticed any extended firing times. Denice Thanks for the input. Mind me asking what prompted you to add a vent after using the kiln successfyully for 20 years? Link to comment Share on other sites More sharing options...
Denice Posted September 3, 2012 Report Share Posted September 3, 2012 Mostly I added the vent because I thought it would reduce the fumes and even out the interior temperature of the kiln. I must say I am disappointed, there is only a slight reduction of fumes and the bottom of the kiln is only slightly warmer. I was hoping to be able to work in my studio while I was firing, my kiln room is attached to my studio, it has a window, a ceiling fan vent and now the kiln vent. It also has and exterior door between the two rooms but it still gets too funky to work in the studio. We have a whole house fan in the garage that I can use in nice weather to clear the air, but it gets too cold in Kansas to use it in the winter. I will use the vent until it wears out but I wouldn't replace it, I'm sorry I spent the money on it but we all make mistakes, I thought I was doing the right thing. Denice Link to comment Share on other sites More sharing options...
Guest JBaymore Posted September 3, 2012 Report Share Posted September 3, 2012 I must say I am disappointed, there is only a slight reduction of fumes and the bottom of the kiln is only slightly warmer. I was hoping to be able to work in my studio while I was firing, my kiln room is attached to my studio, it has a window, a ceiling fan vent and now the kiln vent. It also has and exterior door between the two rooms but it still gets too funky to work in the studio. I'd say that the vent is not working properly if this is the case. Is it the correct size for the kiln? Is it installed absolutely correctly? Is everything in good repair? Is it possible that your supply of make-up fresh air into the room is located near the place that the fumes are being exhausted and it is contaminating the fresh air supply? Unless you are firing some really "funky junk" in that kiln..... there is no reason that the vent would not pick up ALL of the stuff coming out of both bisque and glaze firings. Good ventilation design is actually somewhat complex. Is it possible that your general dilution room vent system is powerful enough that is is pulling a negative pressure on the room space such that the local pickup kiln vent is not able to work against the differential created... and hence the kiln vent fan is there spinning away but not actually moving gases out of the kiln... and most or all of it is still being drawn back into the room? I've seen this many times when I analyze an overall installation. Likely if this is the case it is not enough make-up air being provided into the space. best, .......................john Link to comment Share on other sites More sharing options...
Mark C. Posted September 3, 2012 Report Share Posted September 3, 2012 I have a friend with garage studio and the vent keeps the place from being funky during firing so I think your vent install need to be looked at. The hole is to small or vent line to kinked or makeup air not right-something is not right so check thru the setup again. Mark Link to comment Share on other sites More sharing options...
Denice Posted September 3, 2012 Report Share Posted September 3, 2012 You are probably right I'll have to crawl around and look underneath both kilns and see if there is a problem. My husband installed it and is very anal about this type of installation. He writes technical books about installing, maintaining and operating amusement rides, tractors, airplanes ect. Perhaps someone could recommend a book explaining the in's and out of negative air flow. The vent system is new and has a baffle that shuts off the tube to one kiln while the other one is being fired, there is plenty of air blowing outside and it starts getting warm towards the end of the firing. I have tried closing the window and leaving the door open neither one of those made any difference. The room is only 8x8 but it is 12 feet tall, next time I'll try leaving the ceiling fan off. Any more suggestions? Denice Link to comment Share on other sites More sharing options...
Karen B Posted September 4, 2012 Report Share Posted September 4, 2012 My vent recently broke, and when I fired without it, my firing time was significantly longer, plus I couldn't work in the studio while firing. - One thing to do to check the downdraft is to hold a lighted match over the little holes in the (closed) cover to see if air is being pulled in. Link to comment Share on other sites More sharing options...
Denice Posted September 4, 2012 Report Share Posted September 4, 2012 I've check my air holes with matches several times, it pulls the flame downward, I think my problem is the ceiling fan vent, I use it just to remove excess heat but it maybe pulling air out of the kiln. Next firing I'll leave it off see if that makes a difference. Is the motor broken on you vent you could probably find one on-line at Graingers, they sell replacement motors. We have a Graingers in town and they seem to be reasonably priced if you have one in town it will save you on shipping. Denice Link to comment Share on other sites More sharing options...
neilestrick Posted September 4, 2012 Report Share Posted September 4, 2012 A ceiling fan should not affect the kiln vent. It's just moving air around the room. Make sure the duct to the outside is not clogged, and make sure you have all the peep holes plugged. If a peep is open the vent will not work properly. It only pulls a small amount of air from the kiln. If a peep is open it spoils the negative pressure in the kiln and the fumes will just go out the peep. Link to comment Share on other sites More sharing options...
neilestrick Posted September 4, 2012 Report Share Posted September 4, 2012 Downdraft kiln vents will not even out the kiln enough to make much of a difference. The way you stack the load will have the greatest effect on evenness from top to bottom. Unless you have zone control, in which case you can load it however you want. Link to comment Share on other sites More sharing options...
Karen B Posted September 4, 2012 Report Share Posted September 4, 2012 I've check my air holes with matches several times, it pulls the flame downward, I think my problem is the ceiling fan vent, I use it just to remove excess heat but it maybe pulling air out of the kiln. Next firing I'll leave it off see if that makes a difference. Is the motor broken on you vent you could probably find one on-line at Graingers, they sell replacement motors. We have a Graingers in town and they seem to be reasonably priced if you have one in town it will save you on shipping. Denice Thank you for your suggestion. I already got one from the manufacturer but will keep that in mind for future needs. BTW, I have no fumes either with vent working. Link to comment Share on other sites More sharing options...
Guest JBaymore Posted September 4, 2012 Report Share Posted September 4, 2012 A ceiling fan should not affect the kiln vent. It's just moving air around the room. Denise said she had a celing fan VENT. .........it has a window, a ceiling fan vent and now the kiln vent. So I therefore assumed it is not just the typical air circulation device ala' Casablanca . Interaction of multiple local pickup and dilution ventilation systems is a stock engineering problem when looking at ventilation design. If that vent is exhausting room air, and is a large volume unit (larger than maybe a bathroom type fan), then there is a chance it is affecting the volume of gases moved by the local pickup on the kiln vent unless the make-up air flow and ducting pressure drop impacts was/is carefully considered. Not seeing the installation makes remotely diagnosing such stuff difficult. My actual GUESS is that there is a significant leakage of room air into the system at the local pickup location.... probably at the physical connection between the kiln and the ducting at the bottom floor (the usual culprit), or at the "shutoff" for the second kiln unit. Or that post-fan (positive pressure side), there is a leak of effluent back into the room. best, .....................john Link to comment Share on other sites More sharing options...
Lucille Oka Posted September 4, 2012 Report Share Posted September 4, 2012 Denice, Take a look at your ceiling fan and the manual that came with it. (I am a stickler for manuals). You may have a switch on the side of the ceiling fan which reverses the direction of the rotation of the fan. One direction is lowering the air from the ceiling down (winter setting) or raising the warm air from the room upwards the (summer setting). If you have one it maybe affecting the air flow. But you have alot going on there shutting down everything except the kiln vent is a good test. Link to comment Share on other sites More sharing options...
Denice Posted September 4, 2012 Report Share Posted September 4, 2012 It's not a ceiling fan, it's a duct fan that is in the ceiling that is ducted outdoors through red clay pipe that is typically used for water drainage from the roof, we design the roof system to use these as ventilation of a flat roof but still looks like authentic drainage tile. Like you Lucille I immediately thought wouldn't it be nice if I could reverse it but that's not possible on this fan. I think turning it off and keeping the baffle open in the duct might fix the problem. Thank you every one for the help, I'm testing glazes this week but looking forward to firing my big kiln and trying out some theories. I guess I shouldn't have given up on the vent so soon, I had seen other post of other potters having the same problem. I just chalked it up to a product that didn't live up to all of it's hype, I'll give it another chance. Denice Link to comment Share on other sites More sharing options...
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