Raku kiln from an old electric kiln

[Cyndy Littleton]

After several attempts to keep them going, I have two kilns that I have been told have too much age and need too much work. (Some of you know that I teach at a non-profit art school and rely on donated equipment to keep things going.) Have any of you converted an old electric kiln into a gas-fired raku kiln?

[Norm Stuart]

This conversion using parts from Harbor Freight is the least expensive I've seen - with a good explanation of different configurations.  Never done it myself.

https://www.youtube.com/watch?v=nKcxmT4xZHg

Compare the price with pre-made conversion kits.  http://www.axner.com/burners-and-accessories.aspx

[Cyndy Littleton]

You are a genius! I completely forgot about Harbor Freight and we have one less than an hour's drive. I looked at the video you sent. It looks do-able. I will probably construct a frame and lift system. This is going to be another interesting adventure.

[Nadine Mercader]

I have a plan to do that very thing with one of my electric kilns that is no longer being used nor worth repairing. I have my first Venturi raku burner and all the other paraphernalia so all I need is $ for the propane bottles. I had a raku kiln in Georgia which I had built from firebrick and super high heat insulation panels. I love raku.

[Ersatz Soubriquet]

I have a 10 cubic ft cress that I bought in a school auction, and I was thinking of chopping a hole in and sticking a burner in.

Weed-burners and roofing (asphalt) burners work well and are easy to acquire. The manufacturers will give you an output figure in Btu/h or kilowatts, at a given gas pressure.

What I have doubts about in the set-up in the video is the size/number of propane bottles. To produce the gas to burn, liquid propane has to change to vapour. It requires energy to do so. This energy comes from the heat in the air. The faster you take gas, i.e., the more you turn up your burner, the colder the liquid gets, and this can lead to a drop in pressure, and result in your burner flame reducing. Bigger bottles, or bulk tanks, or bottles manifolded together can alleviate this.

Go for the biggest propane tank you can get. Keep it as far from the kiln as you can. Buy gas leak detector spray, and USE IT ON EVERY FITTING.

I have seen the results of leaking joints. Take care.

[Nadine Mercader]

The gas grill size are fine for raku only. For reduction I would say a minimum 125 gallon tank should work. Many of the propane gas companies down here rent the tank for a nominal fee but the propane itself is fairly expensive now. Have it placed as far as possible from the kiln and in a shaded place.

[Cyndy Littleton]

Thank you everyone for your recommendations!

[Cyndy Littleton]

Have any of you heard about the conversion systems by Summit Kilns? I was comparing different burner systems and stumbled on them.

[Ersatz Soubriquet]

I just went there, it looks like a good system with a reasonable price.

(Not quite as good a price as doing it yourself with a weed-burner though).

The stand looks solid, the burners seem securely mounted. I'd like to see how they arrange shelves in a way that does not obstruct the burners. Shelves over 4" firebricks would be my choice, the pilot burner system looks good, no information as to how it's flued, so can't guess at flame paths.

My only real criticism is the lever ball valve. That type will work great as an on/off, but they're poor at proportioning gas flow for firing rate control. That said, it's all standard bspt pipework, and other types of valve can be easily added.

BASO shut off valves are a good idea if you won't always be present, (if the flame fails they automatically shut off the main gas, and avert risk of an uncontrolled re-lighting, and subsequent loud boom.) Otherwise, common-sense works fine.