Isculpt Posted June 20, 2011 Report Share Posted June 20, 2011 I'm trying to figure firing costs on a large kiln, and the formula I've seen is: amps x volts x firing time in hours (hours are figured as actual hrs x.6, since it isn't on full power the whole time) x cost per kilowatt on my electric bill Using this formula, I have 48 amps x 220 volts x 5 hrs for glaze firing (actually 8 x .6) x 10 cents per hour kilowatt cost I get $5,280! Now, I don't mean to be overly optimistic, but I'm pretty sure that the big new kiln isn't going to cost me $5,280 to fire. Math is not my strongsuit, but what's going on with the decimal?? Should this be $5.28?? Link to comment Share on other sites More sharing options...
Lucille Oka Posted June 20, 2011 Report Share Posted June 20, 2011 I'm trying to figure firing costs on a large kiln, and the formula I've seen is: amps x volts x firing time in hours (hours are figured as actual hrs x.6, since it isn't on full power the whole time) x cost per kilowatt on my electric bill Using this formula, I have 48 amps x 220 volts x 5 hrs for glaze firing (actually 8 x .6) x 10 cents per hour kilowatt cost I get $5,280! Now, I don't mean to be overly optimistic, but I'm pretty sure that the big new kiln isn't going to cost me $5,280 to fire. Math is not my strongsuit, but what's going on with the decimal?? Should this be $5.28?? Where did you get that formula?? Your electric company charges by the Kilowatt hour. How many kilowatts is your kiln rated? If the specs tell you in watts lets say 11,985 watts to achieve maximum temperature, the easiest way to convert to kilowatts is to replace the comma with a decimal point so it becomes 11.985 kilowatts. Multiply that amount by the rate per kilowatt hour usage. For example, without breaking it down to fractions of usage per hour we’ll just use the maximum wattage amount. I will estimate the hours you fire and just use 8. Just to satisfy the example. H is hours firing-8 K is Kilowatts -11.985 C is Cost per kilowatt hour-.10 cents If you fire 8 hours using 11.985 kilowatts per hour and your cost is 10₵ per kilowatt – 8 x 11.985 x .10= $9.588 or $9.59 The formula is (HxKxC) and just plug in the numbers. I want you to know this post was hilarious thank-you for the belly laugh!! Link to comment Share on other sites More sharing options...
AmeriSwede Posted June 20, 2011 Report Share Posted June 20, 2011 Isculpt... The formula that I had learned in calculating the cost was similar, however it is not the amperage or the voltage that you need to figure out the cost, it is the wattage. If you do not know the wattage... then the amperage and voltage figures can be used to calculate the wattage. To calculate the wattage from these two known numbers it is just a matter of multiplying 'amps' times 'voltage'. The calculated answer, divided by 1000 will yield kW (kilowatts). So, using your example... you have calculated the total number of watts (48 x 220=10,560), times 5 hours of burning (=52,800 watts) but are then pricing that number at the kilowatt (unit price). If you divide that total number (52,800) by 1000, that should give you the kilowatt total; then multiplied by $0.10/ kilowatt will give you the total cost of the firing (close estimate anyway). 52,800watts/1000=52.80kW ; 52.8kW x $0.10 per kW = $5.28. So as you felt in your heart $5.28 was the correct answer. Link to comment Share on other sites More sharing options...
AmeriSwede Posted June 20, 2011 Report Share Posted June 20, 2011 ...I found the actual written formula that I had learned... at this link-- Estimating Electric Kiln Firing Costs (bottom of the page) on 'Selecting a kiln' @claymaker.com Link to comment Share on other sites More sharing options...
Isculpt Posted June 20, 2011 Author Report Share Posted June 20, 2011 Thanks to the mathematicians out there. (I'm so poor at math, I had to Google the spelling of "mathematician"!) Lucille, I got that formula at the Axner Kiln site, and I'm pleased that you enjoyed my slight bafflement!! Thanks to Ameriswede for showing me how to arrive at the numbers needed! Link to comment Share on other sites More sharing options...
Marcia Selsor Posted June 20, 2011 Report Share Posted June 20, 2011 $0.10 is a great price per KW hour. Where are you? I pay a low rate too in Brownsville, Tx. I thought Montana at $0.14/KWH was cheap 6 years ago. My oval 12 cu ft. kiln would costs 14.00 for a slow bisque for paperclay. Marcia Link to comment Share on other sites More sharing options...
Lucille Oka Posted June 21, 2011 Report Share Posted June 21, 2011 Thanks to the mathematicians out there. (I'm so poor at math, I had to Google the spelling of "mathematician"!) Lucille, I got that formula at the Axner Kiln site, and I'm pleased that you enjoyed my slight bafflement!! Thanks to Ameriswede for showing me how to arrive at the numbers needed! Not your bafflement but the that fact you said $5,280! That is what I thought hilarious. If that were the price for firing all of the potters would be running for their lives into the woods! I'm happy you got the information you needed. Link to comment Share on other sites More sharing options...
Guest HerbNorris Posted June 21, 2011 Report Share Posted June 21, 2011 I use just about the same formula, but I use a correction factor of 0.75, for the "off time," just to be a little conservative. I would recommend that you check with your power company and see if they have a rate plan which offers cheaper electric rates either all the time, or overnight. My company has what they call the "Real time rate plan" where I pay what it costs the company to buy electricity from various suppliers. They came and installed a special meter, which I pay something like $5/month for; it samples electricity use every five minutes to determine my bill. Using this plan has resulted in substantial savings, particularly since I have the kiln, which I fire overnight, usually. Marcia, I hate to burst your bubble as far as cheap rates go, but tonight, from midnight to one p.m. tomorrow, electricity will cost me an average of $0.02/kwh. Yes, two cents per kwh. Last year I fired a glaze run overnight, and the demand for electricity was so low that the nine hour kiln run cost me $0.56 in raw electricity cost. Of course, by the time you add in taxes, fees, special assesments for the enviroment, etc, it cost more than that, but a special rate plan can save you tons of money if it is available. Oh, the power company also told me I use 138% more electricity than my neighbors, that's how much a kiln can use. I don't mind though, my kiln is atomic powered! Link to comment Share on other sites More sharing options...
Marcia Selsor Posted June 21, 2011 Report Share Posted June 21, 2011 That is great! I had a program for cheaper rates overnight. Where are you that you are getting such good rates? Marcia Link to comment Share on other sites More sharing options...
ceramicfundamentalist Posted June 21, 2011 Report Share Posted June 21, 2011 as opposed to special over night rates i have the complication of a "demand charge" on my electrical bill. i can't remember exactly how it works, but i know that i get charged extra if my peak usage exceeds a certain amount. this often happens when firing a large kiln while using other appliances during the day. i think it always makes sense to fire kilns overnight, or whenever your energy usage is the lowest, just to take advantage of the cheaper rates. i worked it out once, and found that firing during the day was twice as expensive as firing at night. if you want to know the exact cost of firing your kilns i would suggest you talk to your energy company directly and get the exact formula(s) they use. Link to comment Share on other sites More sharing options...
ceramicfundamentalist Posted June 21, 2011 Report Share Posted June 21, 2011 and as a side note, wouldn't it be great if our fancy electronic kiln computers could compute the kiln's total energy usage per firing and display it in kilowatt*hours or joules? Link to comment Share on other sites More sharing options...
AmeriSwede Posted June 21, 2011 Report Share Posted June 21, 2011 and as a side note, wouldn't it be great if our fancy electronic kiln computers could compute the kiln's total energy usage per firing and display it in kilowatt*hours or joules? Actually some can and do! I just bought a SKUTT 1027 from CEBEX, one of our scandinavian ceramic suppliers (Malmö, Sweden) that is supplied with their own electronic controller, the CERAMA G9000, which has exactly that function included on it (displayed in kW hours). As I just got the kiln hooked up last friday, I've yet to use it outside of a couple of test burns. But I am certainly excited about having a kiln again! HOOOWAHHHHH! Link to comment Share on other sites More sharing options...
Guest HerbNorris Posted June 21, 2011 Report Share Posted June 21, 2011 "That is great! I had a program for cheaper rates overnight. Where are you that you are getting such good rates? Marcia " Just outside Chicago. On re-reading some of my post, it seemed a little like I was saying "nyah nyah nyah nyah nyah!" which wasn't my intention at all. Actually, low electriity rates are probably one of the few advantages I have; I bet everything else is more expensive than where a lot of people live; like our property and sales taxes, gas, food, etc. So you probably make out better overall; I just wanted to point out that substantial savings might be had by checking rates with your company. Thanks Marcia, you're always great on this forum! Link to comment Share on other sites More sharing options...
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