firing problem

[AJK25]

I have a Glassglow Model 300 kiln.It has worked beautifully for me for 8 years, so I bought another one, and I am having some issues with the new one. The builder of the kiln told me it may have something to do with the fact that different bricks were used for this new kiln (because the manufacturer of the old bricks went out of business). I am using 208 volt elements because my building is wired for 208 (not 240). I get an FTH error when i run a full kiln (Failure to Heat), and some of my pieces are devitriying. The kiln just cant go fast enough when it hits the 1100 degree mark.The kiln manufacturer is suggesting that i staple fiber paper to the sides of the kiln, and that this will help the kiln run faster (solving the Failure to Heat problem), and also cure the devitrification issue, which he says is occurring because the kiln isnt firing fast enough around the 1300 degree area.

i just wanted to see if anybody is familiar with this problem, and if this sounds like a reasonable solution (or if anybody has a different suggestion for a solution to the problem). I'm also curious if different wiring in the building would solve this problem (i.e. if my building was wired for 240 volt, would that make a difference? The kiln manufacturer says no).

Thanks very much,

Drew Kates

[Valerie Adams]

Were you told that the kiln would behave properly with 208 volt? If so, I'd be pretty pissed off that I had to start making adaptions to a new kiln!
I've got a friend who has one of those kilns; I'll check with her but it's an older one.

[AJK25]

yes, i was told it would work with 208 elements.

i'm ok with putting in the fiber board, as long as it works.

[Kevin Midgley]

sell it.

[Rick Wilton]

Yes the 208v will make a big difference. When I moved in to a commercial bay I had to rework my schedules in all my kilns. I also added an extra element to one of my kilns that was a bit sluggish at 240v and was almost unusable at 208v. Adding some fiber will make a difference but I doubt it will be significant. I'd have gone with a fiber kiln from glassglow before a brick one, you wouldn't have this issue if it was fiber.

Good Luck,

[Rick Wilton]

You say they told you to add fiber PAPER, fiber paper isn't going to have any real insulating properties. You would need to add some fiber blanket or board to make any real difference in my opinion. This is not an ideal solution at all, I'd return it for a fiber kiln or try and sell it.

[Bert Weiss]

208v has 86.66% of the power compared to 240v. The key thing to know is how many watts per cubic foot are available at 208. Watts = volts x amps. If you have no amp meter, the manufacturer should tell you how many amps the kiln draws. In general, I look for 900 - 1000 watts per cubic foot. Smaller kilns need higher wattage than large kilns (when I say large, I am thinking 4' x 8' or larger.) If you don't have enough power, more insulation is not likely to help.

I have no clue about the error message, because I don't use that kind of controller.

[charlie]

they're pulling your leg.

fth is failure to heat fast enough. this means there either isn't enough power, or enough elements. adding more insulation to the sides will prevent heat escaping, which may help it heat up faster, but paper won't do anything because once the binder is burned off, there's nothing to support it.

you need a 208v designed kiln. it has different element sizes than one designed for 220v. kevin is right. i'd not buy from them again; they don't know of what they speak.

[AJK25]

thanks for all of the replies. Regarding electrical issues (Bert), the kiln is pulling 29 amps, and is 24" x 24" x 12" (interior).

[Kevin Midgley]

one more reason to dump the sucker.
4 cubic feet drawing 29 amps..... OUCH

My kiln formula told to me by my element maker was 6 cubic feet and drawing 23 amps at 240v.
It doesn't fire fast fast but it is what all my kilns fire perfectly with.

dump it on someone doing slow ceramics. They admitted using different bricks. It is a joke..... on you if you keep it.
I've made kilns that didn't heat properly and I started over after learning 'that wasn't the way to a better light bulb'.

Look for a kiln with my power formula. It won't be a race horse but it will work..... if it has been made correctly.
No, I am not giving out my home built kiln design, but I sure save on my power bill.

[Rick Wilton]

Kevin your formula has even LESS power. That's not going to help

[Rick Wilton]

If you look at comparable sized kiln from Skutt, http://skutt.com/products-page/glassmas ... s/gm-22cs/

Their 24" brick kiln running at 208v draws 35 amps. If you want to keep the kiln you could consider re wiring the kiln with bigger elements that will draw more power.

If you look at the spec's I posted both the 240v and 208v kilns have 7440 watts. It just takes more amps to get there, volts x amps = watts.

If you put new elements in the kiln you may have to use different wiring and breaker to the kiln.

If the brick they've used is very dense then all this may not help at all anyway.

[AJK25]

it has a more powerful element and is still acting this way.

[Rick Wilton]

It's obviously not powerful enough. The skutt is drawing 20% more than your kiln, there are ways to put bigger more powerful elements into it. It becomes a matter of how much do you want to mess around with a new kiln.

If they told you it would work at 208v and it obviously doesn't they should do something to rectify that. Replace, repair or return.

Good luck,

[Rick Wilton]

Have you actually checked to see what it is actually drawing with an amp meter? Do all the elements work? Are they glowing red?

[AJK25]

yes, the elements are glaring red. My kiln repairman is coming by tomorrow. He has already checked to make sure it's pulling the correct amps, and it is. He is checking the volts tomorrow. Is there anything else to check while he's here? I chatted with Bert Weiss, and he feels that if it is pulling the correct amperage and 208 volts, that is is an issue with the kiln. But if it's not pulling 208v, then it;s an electrical issue.

[charlie]

you're confusing volts and amps.if you talk to your electrician like that, he's either going to be confused, or will have to teach you.

it pulls amps (consumes electricity). that is what the kiln maker can control (by the element size). it is powered with volts, and the kiln maker doesn't have any control over that. it's what comes out of your local transformer.

watts = volts x amps

if the volts goes down, the amp usage must go up to keep the same wattage usage. if the amp usage doesn't go up, the wattage goes down when the volts go down, and thus you get slower rising, or lower max temps, or both.

[Pipwren]

Wow I love that the glass community has so many talented people that share. It helps when people explain stuff like the amps/volts and watts like that! thanks

[Pipwren]

Based on the following information do you think this kiln would have difficulty getting up to the highest temp it is made for (1000 c)
Single phase
25 amp
6kw (internal dimensions 1250 x 650 x 250) Apparently it runs off a regular household plug and in Australia we have 240v.
see http://www.kilnfrog.com/osb/itemdetails.cfm/ID/356

[Babette (Shawn)]

Did you purchase the kiln directly from the manufacturer, or a shop selling Glass
Glow kilns?