by Marc Ward
Q. The burners I have on my kiln are old ventura burners that I've had for over 20 years. Can you please recommend burners for my kiln that is more efficient? My kiln is starting to get harder to fire and is taking longer to get to temperature.
A. Well, not to be too picky right off the bat, but you have Venturi burners, not ventura. The Venturi principle was described by an Italian mathematician by the same name. That's why the term Venturi is capitalized. That little lesson out of the way, let me say that this is one of the most common types of questions I get. It's the old, "my kiln doesn't work right so something must be wrong with the burners" type of question. Hey, the burners are the only thing that's "doing something", so it must be something wrong with them, right? Usually not.
Let me give you an analogy; You live in an old uninsulated mining shack in the Rocky Mountains. Plenty of peace and quiet to make pots, but the bill for your oil burning furnace is equal to the gross national product of a developing country. An oil furnace? You hate the thing and want to get a more efficient heating system. So you call your heating contractor and say you want something more efficient...say a heat pump. "Great", they say. "We'll be out to install it and can guarantee you it's many times more efficient than your oil burning furnace." Next month, no fuel oil bill, but your electric bill has risen to levels that make you woozy. "How can this be?" you ask and at the same time realizing you'll have to sell 148 extra mugs this month to pay the light bill. Many folks simply equate efficiency with lower prices. And the truth of the matter is that BTU for BTU the heat pump is more efficient at producing the heat for your place, but guess what? YOU LIVE IN AN UNINSULATED MINING SHACK. So, yes your burners can build up some scale and become a little less efficient, but the problem is really in the kiln. It's gotten older and leakier. The soft brick has degraded and it's taking longer to fire. But, like your shack, a new heating system is unlikely to remedy your problems. The problem is the structure you're heating.
Many folks think that because I'm in the burner business, I'm copping-out on them when I tell them that their new burners aren't the reason the kiln doesn't work like they want. On the flip side, when a customer calls back raving about their new burners, I say thanks. Then I tell them that the kiln is working great because they designed and built a good kiln. As I mentioned above, your burners can become less efficient. This is usually not enough degradation to even be noticeable unless you compare yearly fuel bills. What happens is that rust builds up on the inside of the burner and causes more turbulence and a change in inspiration pressure (pulls in less air through the back). Again, this is subtle and is not a major factor unless you haven't used these burners for decades and they've been laying on the back porch of your beach house being bathed in salt laden ocean air. Then they'd really be rusted and wouldn't fire correctly. If you feel the need to tune-up your burners you can take a wire brush to them or have them sand blasted. The outside doesn't matter, it's the inside that counts. Burners that are under kilns and firing up can have rust or other debris fall down into or covering the orifice. But, one of the most common problem that happens to Venturi burners usually happens in the fall. I can circle a time frame on my 99 calendar when I'll start getting calls with a certain kind of problem. That problem; corpses. Yea, dead bodies.....just itty bitty ones. Spiders and mud daubers find orifice holes the perfect place to hide their kids and their kid's food. You blow out most of this from the gas pressure, but some always remains. So if one of your burners started acting up in late September or early October, you might want to check out that burner orifice. If your kiln has slowly started taking longer and not giving you the pots you want. It might be time for a new kiln or some refractory upgrades.