Expected Kiln Longevity

[Dick White]

This is a question for the hive mind here, in anticipation of needing to negotiate with TPTB up the hill. The direct question - what is the typical life expectancy of a kiln? The TL;DR  back story - I am the more-or-less manager of a pottery program in a community recreation center operated by the county government. We have 4 well-loved (not particularly) manual kilns, two 20-year old L&L J230s that are used exclusively for bisque and two 15-year old Skutt 1227s that are used exclusively for glaze. The Skutts are rated to cone 8, but are only fired to cone 6. The throughput of the student body results in each of the kilns being fired approximately 75-80 times per year. The hard element holders in the L&Ls have proven their worth, while the unprotected sides of the Skutts are, well, a hot mess given the loading and unloading is a) heavy clumsy shelves, and b) done by volunteers. The elements in the bisque kilns have not been changed in at least 5 years, maybe longer, I can't remember when I did them and don't feel like looking through the records. But, bisque being no big deal, the L&L elements are like the Timex watch ad, takes a beating and keeps on ticking. The Skutt glaze kilns are another story. We get around one year per set of elements, i.e. 70-80 cone 6 firings with cone 8 elements before a firing takes longer than the 20 hours available on the kiln sitter. Doing the math with the above facts, that is 15 element changes (after which the bricks now are so holy that the pins don't stay in) and at least 1,000 firings.  There is a rumor around the building that for first time in decades HQ has some funding available for the most needy projects in the county park system, and I have proposed new kilns (L&L e23Ts for bisque and L&L e28Ts (208/3ph @ 14kw vs. 11kw in the current Skutts)). The question I am expecting from on high and don't have a ready answer - why are my brick kilns wearing out so soon, colonial brick houses (we are in Virginia, so there are a few of those around) last hundreds of years. What is a reasonable life expectancy for a non-production kiln used in a production environment as described above?

Thanks,

dw

[Bill Kielb]

I think I would address it for the context that is presupposed. It is a machine, and as such machines have useable life spans. 10 years is typical. A car is made of steel, steel can last 50 years, yet a cars real lifespan? Bricks last hundreds / thousands. Ancient pottery lots more. The thing is a kiln and like a roof, it has exceeded it’s expected lifespan in an accounting sense (capitalization), in an insurable sense (replacement value), in a warrantee sense, in a safety sense, and in currency of operation. Time for new kilns with digital control and also suggest they not build their next house out of insulating fire brick or fire the house beyond 2000 degrees twice per week or order their next car with a hand crank. Sorry, that brick argument trips my trigger. You can always maintain things and keep them working.

It’s a capital improvement they should address regularly as part of their budget. Time for new kilns, especially if they have the funds. Volunteers often contribute time and energy to benefit everyone and keep costs down. Administrators should figure out how to administrate appropriately and run the best program practical rather than tap into the free labor of volunteers to fill gaps in their budget.

Edited February 4, 2023 by Bill Kielb

[neilestrick]

I've seen kilns that were destroyed in 3 years and less than 200 firings, and I've seen kilns (like one of mine) that have gone more than 2,000 firings without changing a single brick. It all depends on how they're cared for and how they're constructed.

Personally, I don't like using kilns specifically for bisque or glaze because every time you change the elements you do damage to the bricks (in non-L&L kilns), and the glaze kiln bricks don't last as long because they're always firing really hot (in any brand). So the glaze kilns get really beat up and the bisque kilns last forever. I think if you're doing both bisque and glaze in all the kilns you'll get a better lifespan from all the kilns as a whole, and won't have to live with half your kilns being crappy for years and years. I get being able to fit the smaller bisque kiln load into the bigger glaze kiln, but I would consider having two or three e28T-3 and one or two e23T-3 and using them all for both types of firings. If you load the big kilns with bisque you can reduce the total number of loads needed.

The L&L e28T-3 kilns will need a 50 amp breaker, whereas your current Skutt 1227 kilns only need a 40 amp breaker, so take a look at your electrical panel and see if that's doable. In the long run it'll be well worth the cost to upgrade the wiring for the cone 10 kilns, but make sure your center is willing to do that.

Get the quad element upgrade for any kilns you're using for glaze. It'll pay for itself.

The Genesis 2.0 controller is now standard on all L&L kilns!

[Dick White]

Thanks Bill and Neil, part of our context is physical space and part is electrical and part is political. The 4 kilns are crammed into a modest closet room with barely enough space to walk between them. The room is well vented, so that's not a problem. The electrical setup is odd. There are 2 circuits to the room - one side of the room has a 208v single phase 60 amp circuit (for the e23 kilns), the other side has a 208v 3phase 50 amp circuit for the (e28 kilns, though the Skutts only needed 40). Each side has a transfer switch to shift the single circuit to either plug. Thus, we can only run one of each type of kiln at a time, one firing while the other cools and is reloaded. Yes, it's odd and cumbersome, but that's what is there and they've made a point of saying that will not change. I considered the quad elements, but those would exceed the available electric. Interestingly, the eq28 is 14,950 watts while the straight e28 is 14,340 watts; a mere 600 watts difference, but the quad would require 60 amps, a nonstarter, while the straight fits in the existing 50 amps. The only thing the electrician will need to do is remove the inline 3 phase contactors needed for the manual Skutts. And yes, Genesis controllers! Do you know if L&L now installs the current sensor standard as Skutt does?

And yes, Bill, I am with you on all of that. But HQ doesn't think that way. They can't see the kilns (and the students can barely see them) and don't have to use them. They can see the swimming pool, the weight machines in the fitness room, and the tennis courts and baseball fields. Those things are obvious when they are in disrepair and get fixed (or in the case of the weight machines, replaced as soon as they are seen as at a competitive disadvantage to those at Gold's Gym or LA Fitness, lest we lose customers). The kilns - as long as I can keep them propped up, there is no capital budget or plan for timely replacement. The only paid employees are those in direct paying customer contact, i.e., the teachers (of which I am one). All indirect operations are done by volunteers who are "paid" in kind with free access to the facility (but limited, lest it become taxable income as a fringe benefit - yes, the IRS took issue with letting the volunteer golf course attendants play for free) .

Thanks again for your wise insights.

dw

[GEP]

12 hours ago, Dick White said:

The question I am expecting from on high and don't have a ready answer - why are my brick kilns wearing out so soon, colonial brick houses (we are in Virginia, so there are a few of those around) last hundreds of years.

Make sure to explain that the official name for kiln brick is “ceramic refractory brick” or “fire brick” and often called “soft brick” and is nothing similar to the masonry bricks that houses are built with. I would refer to it as “soft brick” as much as possible (hehe) and explain that it can be cut with a hand saw. 

In fact, I think this is a winning argument for why the Skutts should be replaced with L&Ls, by explaining and showing that the hard ceramic element holders have protected the soft brick in your existing L&Ls, and thus the L&L kilns are a much longer term investment that will not need to be replaced for another generation. If this means you can get the Skutts replaced but not the older L&Ls, that’s still a win for your program!

(Edit to add: one of my L&L E23Ts is also 20 years old, and gets fired about 70 times/year. I have zero interest in replacing it, because “Dr. Evil” is still in impeccable shape. The outside is a bit corroded, but the inside is pristine.)

Edited February 4, 2023 by GEP

[Bill Kielb]

1 hour ago, Dick White said:

They can't see the kilns (and the students can barely see them) and don't have to use them. They can see the swimming pool, the weight machines in the fitness room, and the tennis courts and baseball fields. Those things are obvious when they are in disrepair and get fixed (or in the case of the weight machines, replaced as soon as they are seen as at a competitive disadvantage to those at Gold's Gym or LA Fitness, lest we lose customers). The kilns - as long as I can keep them propped up, there is no capital budget or plan for timely replacement.

Sorry to hear that, hope you do find some success and get a replacement or two.

[neilestrick]

On 2/4/2023 at 8:42 AM, Dick White said:

e. I considered the quad elements, but those would exceed the available electric. Interestingly, the eq28 is 14,950 watts while the straight e28 is 14,340 watts; a mere 600 watts difference, but the quad would require 60 amps, a nonstarter, while the straight fits in the existing 50 amps

All models are available with Quad elements without any change to the power requirements, so you can get the e28T-3 with Quads- you don't have to get the eQuad model that has higher power.

[oldlady]

dick,  if you do not have a brick available to you, i will get one to you.  it would be a great demonstration if it can be handled by whoever makes the decision.    it can be sent to  wherever the meeting of the  group  takes place.   tell them to press a fingernail into the brick and see how "soft" a softbrick is.   that demo should do a great deal of good for your side if they pass it around to everyone who is involved in the decision.

[Callie Beller Diesel]

If the powers that be need to see the repair state of the kilns, get them images, and show the side by side comparison to a new kiln. Emphasize that you will not be able to keep them propped up for a lot longer under current usage. Another question to consider is do the sub-par operations or conditions of these kilns contribute in any way to potential liability regarding the volunteers? 

[neilestrick]

In addition to broken element grooves, the color of the bricks is a pretty good indicator of age and condition. New bricks are a light cream color, old bricks turn yellow and become soft and brittle. The darker the yellow, the worse they are. I had this very conversation with a customer a couple of weeks ago. The bricks in their kiln were in halfway decent condition in terms of breakage, but they all had little chips in them and a few of them needed replacing due to large chips. Plus it needed elements, relays, feeder wires, and  a wiring harness. It was going to be a $800 repair, which would have been fine if the bricks better, but they were all very yellowed and super soft and brittle, and weren't likely to make it through the repair without further damage, or last as long as the new elements. We had talked about replacing it the last time I worked on it, so they were prepared for the bad news and ordered a new kiln.

[Dick White]

Update, and thanks for all the suggestions and insights. We won. Sorta, we hope. They have agreed to consider approving purchase orders for the 4 kilns. Some minor grit in the gears is recent price increases since I first submitted the proposal, but hopefully they will continue forward. One other "change" is instead of asking for the upgrade to the quad elements in the two e28s, I am going to shoot the moon and ask for Advancer shelves instead of the standard furniture kits. Wish me luck, and thanks again.

dw

[oldlady]

congrats, dick.     where do you buy the equipment you are allowed to buy?   i ask because jim bailey gives discounts on shipping and is very happy to help a large purchase.   call him and ask before the figures are set in stone.    or bricks.

[Dick White]

Alice, definitely going to get Bailey's clone of the Advancer shelves. Several hundred less list price, and we have a set of them for one of the gas kilns at school, they are just as good as the real Advancers we have for the other gas kiln. I will call them tomorrow to see what kind of price he can quote for the 4 kilns. It would be awesome to do one PO for the whole lot.