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Kiln Will Not Fire


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#1 Kabe

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Posted 05 December 2013 - 11:22 AM

I work at a collage that has a 1988 Alpine kiln, Natural draft, Model ND-16, and the ring burner will not stay lit, which sets off the flame failure sensor. we have replaced the photo sensor, and the UVM control box and the highfire /soak switch. All the relay look clean and with no visual sign of shorting out. The kiln has been looked at by a kiln tech, to no avail. Someone in Tenn. said that it works off of micro volts and if there is a break anywhere in the wiring system (talking about a microscopic crack in the plastic coating covering the wire, not the wire itself) that will allow a single electron to escape and that is one to many for the electrical system. The power light on the control panel fluctuates. That does not seem right to me. I cleaned the key operated, power switch, but it still fluctuate. Would installing a new power cord make a diff?   when you test the currant on both sides of the wiring of the photo light where it hooks into the panel the meter bottoms out like there is 500 volt going through it. you get the same reading at the control box. Why? Where would it pick up another leg of power or is that something to do with the way the photo light sensor works? We are to the point to where we are going to bypass the system and install a baso valve with a thermocouple, so we can fire the kiln and give the students their wares. Any advise would be helpful. They hope to replace the kiln this summer.  thank you. Ain't clay fun, Kabe



#2 Wyndham

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Posted 05 December 2013 - 12:25 PM

Look at each junction from the main breaker that might be bad to the circuit box that feeds the kiln as possible failure points. The blinking power light is a valid clue as to what is wrong but no idea where. If there is a plug in 110 or 220 that could be shorting out.

sorry but not much else I can think of.

Wyndham



#3 Marcia Selsor

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Posted 05 December 2013 - 12:43 PM

Have you cleaned the orifices? Are the pipes rusty?Some rust could be clogging up something.I had wasp nests in the Geil and the Olsen burners at UTB. Both updrafts.

Marcia

#4 JBaymore

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Posted 05 December 2013 - 01:18 PM

Does that unit have a Honeywell flame safety controller on it? Can you get the model number off of it?

 

Whatever controller it has, it likely is a modular unit that plugs into a socket inside the outer "box" that houses it. Power down and lock out the electrical to the kiln. Take off the outer box. Gently remove the controller from the socket. Then simply put it right back in the socket, screw on the cover, and re-test the system. I've found that over time the connections in that socket setup can sometimes get a bit of dust in them... and sometimes all it takes is a re-seating of the unit to fix such a problem.

 

Does the pilot (ring burner) ignite and remain on for any period of time at all and then go out, or will it simply not remain on after the initial ignition sequence? Or does it simply not ignite at all on the ignition sequence?  THAT will tell a lot about the possible source to look at.

 

 

 

If it lights and then shortly goes out, .......... have you cleaned out the (usually installed) sighting tube that the UV detector is looking through at the flame on the ring burner? Also clean off the face of the UV detector itself.  This is a common cause of issues.

 

Have you tested or replaced the UV detector itself? (You should always have a spare good one on hand.)

 

Try removing the UV detector from its mount, and directing it at a plumbers propane torch as you try the ignition sequence. If that proofs the pilot flame and locks in the main gas solenoid valves ..... look at Marcia's comments above. The ring burner flame may be really weak or very yellow....... not enough UV prioduced to tell the system the flame is proofed.

 

Also check that the UV detector sighting tube is actually lined up correctly on a section of the ring burner that has flames present.

 

best,

 

................john

 

PS:  Some of thiose old "power" lights are of a type that do "fluctuate".


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#5 neilestrick

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Posted 05 December 2013 - 03:08 PM

Have you called Alpine?

 

Agreed, often the power lights flicker. That doesn't concern me at all. The power source for that kiln should be standard 110/120 volt, like a regular household plug. There's no way you should be able to measure 500 volts anywhere on that kiln. 

 

Does it have the Fireye system? Look on the back of the control box. If there are two red boxes, then yes, you have Fireye, and chances are you need to replace the cards (circuit boards) in one or both of the boxes. Those cards go out all the time. Call Alpine to figure out which one, as one has the lightup sequence but I don't remember which. Joe is a good guy and will be very helpful.

 

A relay could very well be bad, even if it doesn't look bad. You'll have to check the output on each one to find out. They don't usually go bad, though, because they only switch once or twice for each firing.

 

It's also possible you have a bad solenoid on the gas line, however if the pilot ring lights during the startup sequence, then that is not the problem.


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#6 JBaymore

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Posted 05 December 2013 - 03:25 PM

There's no way you should be able to measure 500 volts anywhere on that kiln.

 

That one got me too. Figured the multi-meter was set wrong. ;)

 

If it WAS accurate....... "there's your problem" :lol:  :lol:  :lol:

 

best,

 

................john


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#7 neilestrick

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Posted 05 December 2013 - 04:12 PM

 

There's no way you should be able to measure 500 volts anywhere on that kiln.

 

That one got me too. Figured the multi-meter was set wrong. ;)

 

If it WAS accurate....... "there's your problem" :lol:  :lol:  :lol:

 

best,

 

................john

 

 

The control box would be hotter than the kiln!  :lol:


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#8 JBaymore

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Posted 05 December 2013 - 05:06 PM

Hybrid gas/electric kiln. :lol:


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#9 Kabe

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Posted 06 December 2013 - 01:56 PM

We have replaced the UMV controller that is on the outside of the electrical panel and checked all the lugs where it plugs  in. It is a fireeye and we have replaced that. In fact when the eye sees fire it drops to 400 volts, maybe it we hade four eyes on the kiln it would fire. The ring will stay lit for a short time then the flame failure light comes on, that was why we thought it was the fireeye. Like someone said it is not the solenoid because it will open to lite the ring burner, it just will not stay open. We have repositioned the eye so it could get a better view but it still will not stay lit. My son, who is a electrician, said that there is no way we can get that many volts off of a 110 circuit. I have no Idea why we get this false reading. We even tested it with two different meters to see if it was repeatable and it is.  A co-worker of mine recommended the tongue test like how you do a 9 volt battery but I declined. We did call Alpine but they said they don't work on this old of kiln anymore,  although they did direct use to the parts we are using. The kiln tech who worked on it also changed out the control box that is inside the kiln. We are baffled as to what is wrong. We ordered a valve with a thermocouple and we are going to bypass the photo-eye system and set it up like a water heater. The kiln the instructor used at college was set up that way. The valve may be here Monday.   I do believe that whatever produces the 500 volt reading is the problem, but I do not have the training to chase it down.  At this point the instructor has a complete semester of bisque  students wares and about a week left to get them glazed and fired. Bummer for everyone involved. Ain't clay fun, Kabe  Thank you again for the help. On the bright side the school may get a new kiln this summer. We need to nurse this one through for one more semester. This one was installed in 1987.



#10 neilestrick

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Posted 06 December 2013 - 03:07 PM

If the bricks are still good, you can order a new burner system for the kiln and save a lot of money vs a whole new one.


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#11 Kabe

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Posted 06 December 2013 - 04:08 PM

The bottom bricks are sort of falling out the bottom and I think if they get a new kiln it will be a down draft but I'm sure they will save the good brick.



#12 neilestrick

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Posted 07 December 2013 - 09:29 AM

I would not mess with tearing any bricks out of that kiln. Behind the brick is either a layer of vermiculite and cement which is a total mess, or something like a fiber material, possibly even something with dangerous fibers like an asbestos type material. If it's an old enough kiln that it was built when Alpine was in California, we don't know what they used behind the brick. I was production manager at Alpine for a couple of years when it was in Sturtevant, WI, and we had no record of what they used before the company came to Illinois, before Wisconsin. Plus all the bricks are mortared together, and you'll never get them clean enough to use for anything, assuming they don't crumble when you tear them out. Just fork lift the whole thing out of there and send it to the landfill.


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#13 bny

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Posted 25 December 2013 - 04:34 PM

Find a digital multimeter and measure again first on a high AC volts range, then DC. Bottoms out sounds like a moving needle meter. There is no way to get 500V out of 120V without going through a transformer, or a switching element and inductor.

Gas safety valves are millivolts, not microvolts. A thermopile (series array of thermocouples, from the outside looks like a metal cylinder with wires emerging) generates typically 750mV measured open circuit. This goes to a sensitive solenoid valve and allows it to remain open as long as the thermopile (in flame) is hot enough. Defective thermopile, insulation defect, or bad millivolt valve are all possible causes of shutoff.

"Allowing a single electron to escape" is a cowboy silly overstatement of the physics, but it is true that insulation defects or loose or corroded connections are particular troubles in a low voltage system that must generate sufficient current to operate something mechanical.




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