What BTU does a candling burner need to produce?

[jrgpots]

My two burners in my kiln can go from 80 to 590 degrees fahrenheit in about 20 minutes when the kiln is empty.  So, I think they will be able power through the firing.  however, I need to build two  candling pilot burners.  My question is how many BTUs should these burner produce per hour???  The kiln is 12.5 cubic feet with 9" IFB side walls.

Jed

[Bill Kielb]

1 hour ago, jrgpots said:

I need to build two  candling pilot burners.  My question is how many BTUs should these burner produce per hour??? 

For natural gas- 
large pilots for thermopile (not thermocouple) use are in the range of 1 cubic foot per hour to 1-1/2 cubic foot per hour. That would be Approximately 1000  - 1500 btu per hour. If you have two of these, that would be 2000 - 3000 btu per hour. Most folks struggle to keep their temp from running beyond a few hundred degrees And complain this is too much. (Not sure why actually, they are likely missing that rate thing)  Opening a damper and dialing back the pilot pressure would solve this issue. 3000 btu is just short of 900 watts per hour just in case you get the urge to use light bulbs BTW.

Regular pilots (for thermo couples) are half to two thirds of this but I think  two average pilots likely would be fine to get the kiln slowly over 300 in eight hours or more. Definitely depends on your damper setting and leakage or draft through your kiln as well as what temp are you looking for in the morning? 

Cost in Illinois have been recently down into the .26 - 36 per therm. A therm is 100000 btu, which is basically 100 cubic feet which at your highest rate of 3 cubic feet per hour, gives a bunch of hours before you use Up you 30 or 40 or maybe even 50 cents worth.
 

Propane is double the BTU, BTW or about 2000 btu per cubic foot.

[neilestrick]

The primary purpose of a pilot burner is to keep the main burner lit until the kiln is hot enough that it will stay lit on its own. The secondary benefit is that it can also be used to slowly heat the kiln for drying out work if you want to bisque fire in it, or to give a slower initial climb than the main burners can do. My gas kiln had 24 cubic feet of stacking space, and my pilots would get it up to 200F overnight. I would also run the blowers on slow speed to move the air around. I would regularly bisque and glaze fire large 45 pound planters in it without any problems, even though once the main burners turned on it would climb very quickly to 500F. If everything is good and dry, that's not an issue. If you're using power burners, putting a rheostat on the blower so you can throttle it down will allow you to run them at lower power than just closing the flaps.

I used simple old-school water heater standing pilots like THIS, which is all we ever used on the gas kilns we built in grad school, too You can probably find them cheaper than this link, it was just the first one I saw. The thermocouples for them are inexpensive, and thread right into the burner for perfect alignment, and the other end screws into a Baso valve. It's a simple, inexpensive system that works very well.