Inherited a kiln

[Joseph32]

I inherited a kiln with a place in renting but am a little concerned. The guy didn’t actually have burners, but instead had just drilled a gas line a few times and dropped small pipes on top to direct the flames (pictures in imgur link). He also has each “burner” on a totally separate shut off. Has anyone seen something like this? Any advice? Will it work?

Pictures

[neilestrick]

Umm, why are the burner pipes inside the kiln? There are a lot of things wrong with that kiln if it was used for ceramics. I'm wondering if it was used for something different. I definitely wouldn't try to use it.

[Joseph32]

It definitely was used for ceramics, I know that for sure (speaking with the neighbours and the guy who bought the house-they had to clear out the ceramics). But you’re right, the whole thing is a little concerning haha.

[Bill Kielb]

Cast iron burners generally well below 2000 degrees. I think they simply melt at 2200 degrees. Even Cone 04 seems too close. Not sure this home made contraption shouldn’t just receive some proper burners and a thorough check out before use,. The debris in the bottom is interesting as well.

[Joseph32]

5 minutes ago, Bill Kielb said:

Cast iron burners generally well below 2000 degrees. I think they simply melt at 2200 degrees. Even Cone 04 seems too close. Not sure this home made contraption shouldn’t just receive some proper burners and a thorough check out before use,. The debris in the bottom is interesting as well.

Thanks, that’s good to know. I have no idea what kind of pots were coming out of this thing. Do you have a recommendation for who to consult about burners or if it’s even worth it?

[liambesaw]

Looks more like the kind of kiln you fire evidence in, not pottery.

[Bill Kielb]

I really like ward burners and there are many here that have built their own kilns. Give them the typical construction and interior size and they likely will spit out about how many BTU and how many burners. My background is engineering so often a bit overkill for a kiln. If you can provide pictures inside and out that would be helpful. I am guessing a number of them are asking themselves how it’s made and how much heat will it take.

[Joseph32]

More pictures

Measurements are 5’Lx4.5’Hx3.5’W. the floor is bricks on top of a concrete pad.

Two of my other concerns are what the door is made of (some type of concrete) and the floor (some type of ceramic tile), though there are bricks making up the floor beneath it.

[neilestrick]

The floor appears to be only 1 brick thick, which is not thick enough. It will spall or at least calcine the concrete underneath. There are no burner ports for proper burners, or room for them. The outer layer appears to be common brick with cement mortar. That mortar will calcine and fall apart, as you can see in the upper right corner. I think whoever built it had an idea of what a kiln should be, but didn't do any actual research. I wouldn't put any effort into making this 'kiln' work. Tear it down and rebuild it properly.

[Joseph32]

2 hours ago, neilestrick said:

The floor appears to be only 1 brick thick, which is not thick enough. It will spall or at least calcine the concrete underneath. There are no burner ports for proper burners, or room for them. The outer layer appears to be common brick with cement mortar. That mortar will calcine and fall apart, as you can see in the upper right corner. I think whoever built it had an idea of what a kiln should be, but didn't do any actual research. I wouldn't put any effort into making this 'kiln' work. Tear it down and rebuild it properly.

The problem is that I’m a renter so I can’t really go around tearing down parts of the property and building large projects. The potters guild is full and even the wait list is full so I can’t fire there. This is really my only option if I want to do ceramics so I’d rather try make it work as much as possible. I know it’s a crappy setup, but right now it’s what I’ve got. I obviously need to look at a burner, does anyone have any other advice if I were to try work with this?

[Benzine]

42 minutes ago, Tehol123 said:

The problem is that I’m a renter so I can’t really go around tearing down parts of the property and building large projects. The potters guild is full and even the wait list is full so I can’t fire there. This is really my only option if I want to do ceramics so I’d rather try make it work as much as possible. I know it’s a crappy setup, but right now it’s what I’ve got. I obviously need to look at a burner, does anyone have any other advice if I were to try work with this?

Neil is a kiln expert, who builds and services all types of kilns.  Bill is also an expert.  

I would heed their warnings, and take their advice, even if it contrary to what you were hoping to do.  

If you do want to fire ceramics, you are better off looking for a used electric kiln.  If you want to fire with gas, you can modify an electric kiln to do so.

Alternately, just look for a community studio, where you can get experience, without committing to equipment.

[neilestrick]

35 minutes ago, Tehol123 said:

The problem is that I’m a renter so I can’t really go around tearing down parts of the property and building large projects. The potters guild is full and even the wait list is full so I can’t fire there. This is really my only option if I want to do ceramics so I’d rather try make it work as much as possible. I know it’s a crappy setup, but right now it’s what I’ve got. I obviously need to look at a burner, does anyone have any other advice if I were to try work with this?

To use real burners, you'll have to make holes in the walls for burner ports. You'll also need to have space inside the kiln on either side of the stacking area as fireboxes where the flame comes in. You don't want the flame shooting directly onto your pots. That means the actual useable space inside the kiln will be much smaller than what you see, probably only one shelf wide. The kiln wasn't built with that in mind. I also think the flue opening is probably too small.

Is there a damper in the chimney? With a chimney that short, and having to cut burner ports, you'll want to use power burners because you can just use 2. But you'll need to figure out how much gas you'll need, and if the current gas lines can even supply the BTU's needed for an all-hard-brick kiln.

If the floor of the kiln is truly just one brick thick, then it's really a safety issue because the concrete below could spall (explode). The mortar in the outer layer of the walls could do the same thing.

I would talk with the landlord and see if you can rebuild it properly.

For what you might spend on burners, you could buy an electric kiln that you know is safe, or even an old used electric that you convert to gas.

[Babs]

Don't ignore advice given here.

Dont know why owner allowed that on his property.

A second hand electric kiln may cost you less in the long run.

Safety first.

[Joseph32]

Thanks for all the help and the information/input from everyone. Just to calm everyone's hearts (or maybe I'm reading a couple of the posts wrong, text is hard that way sometimes), I'm not going to ignore advice, that's why I came here to ask. That said, as I mentioned earlier, I can't join the guild around here; it is so full they won't even take any more names on the waitlist so I'm stuck with as much as the landlord allows or it seems, if that isn't much, nothing. 

8 hours ago, neilestrick said:

To use real burners, you'll have to make holes in the walls for burner ports. You'll also need to have space inside the kiln on either side of the stacking area as fireboxes where the flame comes in. You don't want the flame shooting directly onto your pots. That means the actual useable space inside the kiln will be much smaller than what you see, probably only one shelf wide. The kiln wasn't built with that in mind. I also think the flue opening is probably too small.

Is there a damper in the chimney? With a chimney that short, and having to cut burner ports, you'll want to use power burners because you can just use 2. But you'll need to figure out how much gas you'll need, and if the current gas lines can even supply the BTU's needed for an all-hard-brick kiln.

If the floor of the kiln is truly just one brick thick, then it's really a safety issue because the concrete below could spall (explode). The mortar in the outer layer of the walls could do the same thing.

I would talk with the landlord and see if you can rebuild it properly.

For what you might spend on burners, you could buy an electric kiln that you know is safe, or even an old used electric that you convert to gas.

Thanks again for all this information-it's really helpful. To answer your questions, there is no damper unfortunately, and the floor is only one brick thick with, as I said, some type of ceramic tile on the floor. Looking closer at the side walls, they have insulation between the bricks and the other brick, though it doesn't seem like much and I have no idea the type of insulation. As you suggested earlier, there is significant damage to the upper part of the  outer wall of red brick. I've glanced through the Olsen kiln book before in university so I'll probably make a point of getting that again and going through it so I have a better idea of what I want to build and how before I speak to the landlord. I would love the challenge of building my own kiln though and seeing as I have a bunch of the resources here, I think I'll at least try that before I get an old electric.  

A couple quick questions if someone can answer:

1. What is the best way to estimate the BTU's available currently?

2. Is there any other resources you would recommend if I was going to build something like this or where I should look for parts, etc? I saw someone already recommended Ward Burners. I am up in central Canada if that makes a difference.

Just so you know my background, I fired gas kiln  cone 10 in reduction for about a year in university, though that was obviously a much better situation than I'm in right now.

[Bill Kielb]

Can you tell me fuel type (probably natural gas), pressure (11” max if residential) and distance from the gas source (approximate) these can be in any units you are comfortable with  (Imperial or metric) if those are interior dimensions this is on the order of 78 cu ft! Mostly high not wide so we have height to work with and depth.  No matter what, you probably will want to add a layer to the floor, maybe ifb since nothing will sit in it but your first shelf.  Cone ten at that size without much thought is probably  a million Btu or more (Just a quick guess though),  Existing gas lines cast up through the concrete in iron pipe not so great, what is the flue lined with? Will need a damper and to engineer a chimney height but likely can just extend the existing with square to round transition. It will be a challenge for sure. I am not certain I wouldn’t cut a new opening in the side of this thing and brick up the existing so I have some room for conventional burners.

lots and lots of thought here, sure you don’t want to convert an old electric to gas first?

[Joseph32]

Sorry for the delay in replying, on vacation now. I think it is a 5(?) PSI 50 ft line of natural gas, 3/4”. The flue is not made of fire brick, I’m not sure what type of brick/concrete it is. It is red and 1” thick. It’s probably 6.5 ft right now, how high do you think it should be?

My thought at this point is to cut the outer brick wall off about 8-12” off the ground and build the kiln from there, probably 3.5Hx3.5Wx3.5 or4L. I already own the tools to cut the brick with. I’m not sure what I would use to mount the kiln crosswise but I would maybe find some type of stainless cross beam and bolt into the bricks. I’d probably want to end up with a kiln This would allow me to put atmospheric burners below the kiln. My issue would be with the roof. It appears the bricks are attached to some type of concrete in an arch and I don’t really know how to remove this. I could try keep the roof as well as there is no damage to the current concrete so perhaps it is more heat resistant than the red brick is. I can’t really do any of this for a couple weeks though and have to get permission as well. 

[neilestrick]

Any concrete or red brick will not hold up to high temps. I'm guessing that you plan to fire to cone 10, or at least cone 6? It could be that it was built with refractory castable, but who knows... It could all be concrete. I have a hard time believing the kiln was fired very hot before, based on what I'm seeing in the photos.

I would not save any of the existing structure as it is currently built. The floor is not safe. Salvage the firebrick from the inner layer and use it, but everything else is trash unless you can confirm what the materials are and if they'll handle high temps. I get that you're trying to make this work, but I don't see how it can be done properly and safely without  getting more bricks, or building something considerably smaller with the bricks you have.

I don't understand what you mea by 'mount the kiln crosswise' with a stainless beam.

 

[Bill Kielb]

I am going to guess it’s low pressure residential gas which tops out at 11”  - or less than 1/2 PSI. Medium pressure gas is 2 PSI just to give you an idea. So just working from memory my last design was 800000 btu,  downstream of a 600,000 btu load  all fed at medium pressure (2PSI) and about 50 ft.  Of 1” pipe was needed at 2PSI to support the 800,000 btu load.

you likely have 1/4 that pressure available (Residential) so maybe a 2” — 3” diameter pipe. So these are wild guesses and I don’t want to discourage you but want to stress that if you are really committed then lots of thought needs to go into this.  If what I speculate is true above then we need to think in terms of minimizing the load, so less gas which means more insulation which means being creative on the disassembly and reassembly of the kiln.. removing the bottom rows of bricks is a pretty big commitment but who knows if there are brick ties  and reinforcement in the existing  exterior brick and what condition they are in.

but let’s assume you can punch a jack through, retain a section of the brick above and cut out what you need while installing block and IFB or whatever you like to raise the floor. Then on the interior you create a flame trench for two power burners each side and refabricate the flue to accommodate the new height.

I will stop now as my point is doing this is very possible and there are better and worse ways, but to do this we are really getting into a whole bunch of quality leg work and design so you don’t waste money, effort and risk creating a kiln that just don’t work too good .........of which you do not own actually.

I love a challenge, but ...... are you sure you don’t want to just convert an electric to gas initially? This could be great fun if it’s your thing but we have not even discussed the operating characteristics of these kilns in which experience is  extremely important to a workable design.