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RebeccaC

"warming" my controller

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I live in SE Oklahoma, and the nights here lately have been running in the mid 20's temperatures.   My question is:  do I need to "warm" my  new L & L kiln controller/panel before starting my bisque firing in the evening when the temp is dropping?   The slow bisque program runs about 13 hours, and I'm adding a 2 hour pre heat.   

Seems I read about this "warming" idea somewhere once, and am not sure if it is really necessary for the electronics on the control panel.  My kiln is situated in a small 2 car garage/building,  concrete floor,  metal sides and roof, no insulation, and plenty of ventilation.  I also run the automatic vent that came with the kiln.   I am not fond of the idea of a space heater running just for the controller, but will if needed.

Any thoughts on this?

Thanks for all the help.

RebeccaC

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It should work fine as long as you're above 0 degrees. The controller can't read negative temps. That said, it it's behaving oddly due to the cold, put a small space heater near it to warm it up. Once the kiln starts radiating some heat it won't be an issue.

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Beware of heating it too much. This is the problem I’ve been having with my kiln.  I have a Genesis controller attached to an Olympic kiln. I’m in Australia and we’ve had some extremely hot weather lately causing board overheating errors. This happens when the board reaches 158 degrees F. I’ve had to wait for cooler temperatures and fire overnight with a fan pointed at the controller to try to keep it cool. It’s quite a problem when the program stops midway because it’s too hot.

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Thanks for the reply, Linda.

In the summer here, it sometimes gets over 100 degrees, and even with opening the two 6' doors, and running a room pedestal fan, I sometimes put a really small fan pointed directly on the controller.  I do worry about the heat, and don't want to fry the electronics!

Thanks, again.

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My understanding of the issue is that the controller electronic board is fine in cold temperatures. It is the thermocouple that causes issues at low temperatures. The thermocouple operates on the principle of the galvanic electric current (which is minuscule, measured in milivolts) generated at the intersection of two dissimilar metals. The hotter the joint is between the two metals, the more current it generates, and the controller measures this increasing electrical voltage to "know" how hot the kiln is getting. The ubiquitous K-type thermocouple is made of chromel-alumel, for which the decreasing electric current output as it gets colder reverses from positive to negative at around 0C (i.e., freezing). The controller logic does not know what to do negative numbers, so it bombs out. Directing a heater at the controller probably will not do anything useful as the tip of the thermocouple is inside the kiln. You have to warm the interior of the kiln above freezing for the thermocouple to start generating positive numbers that the controller can use. My thought is that you don't have to warm up the whole kiln, just the thermocouples, and once the thermocouples start generating positive numbers, the controller will start the elements. For that, it seems that a hair dryer blowing down the inside of the kiln over the thermocouples should warm them enough to get things going.

It is also mentioned earlier in the thread that the controller also has issues when things are too warm. Yes, this is a controller problem. When the semiconductors in the logic and memory chips get too warm, the electrical signals carrying the data to and fro within the computer chips start jumping their tracks and virtual train crashes start happening, with unpredictable consequences. The controller is programmed to sense ambient temperatures around the circuit board and shut down well before the circus trains might crash and spill their clowns.That's somewhere around 150F.

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If the kiln is below zero, the best way to get it going is to heat up the thermocouples, start the kiln immediately, and have it shoot up to about 150 degrees and hold there for an hour or two. That will get the bricks warmed up all the way through. Then you can load the kiln and start it up. The heat being held by the bricks should keep it warm enough to get it started again. A hair dryer may work, but it could be difficult to get the bottom thermocouple in a 3 ring kiln heated up, and the warm bricks will make loading much more pleasant.

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Hi Rebecca,  I’ve been waiting for days where the temperature is under 100 and leaving my firing until overnight. I also use a fan pointed at the controller and have the doors open. 

Thanks for you response Dick, do you know if there’s anyway around the overheating problem other than what I described above to Rebecca?

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1 minute ago, Linda Lees said:

Hi Rebecca,  I’ve been waiting for days where the temperature is under 100 and leaving my firing until overnight. I also use a fan pointed at the controller and have the doors open. 

Thanks for you response Dick, do you know if there’s anyway around the overheating problem other than what I described above to Rebecca?

There are two things to consider when trying to keep the controller cooled. First, there has to be cool air coming into the room. In a hot room, you can't cool the controller effectively. So open a window or door and put a big fan in it that blows cool air into the room. Second, put another fan that blows directly at the controller. If it's a continual problem, try putting a fan on the ground aimed up at the controller, so it blows air directly into the controller through the vents at the bottom of the control box. It's actually the back of the controller (the board) that needs to be cooled. I've even mounted a little computer fan inside a control box to blow air on the controller and relays.

Different controllers are set for different max board temps. Some will shut it down at 140F, some at 175F. It just depends on what the manufacturer has decided is good. 

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