MikeAlmogy Posted March 17, 2019 Share Posted March 17, 2019 Hi all. If this topic have already been covered then i will be most thankful for a link. I want to build an electric furnace, Both for heat treatments and for pottery. I have a given dimensions and i need to figure out what size and resistance coil i need. There are lots of calculators out there but they all "attack" the problem on a different angle then the one i want. Basically my problem is this: I have a space that i need to heat (the inner space of the furnace) but i have no idea how long of a coil i need. More then that, i do not know how many watts i need to heat the space in a reasonable time. When i'm building a gas forge i know that in order to get good results i need X number of burners (of a certain type and characteristic) in order to heat a Y area. I have no idea how many watts i need to heat a certain area in a reasonable amount of time. I saw a youtube video of a guy called VegOilGuy who build a melting furnace of 1200 degree but it takes him 3 hours to achieve that. Thanks, Mike Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted March 17, 2019 Share Posted March 17, 2019 Without knowing anything about how it's going to be lined you are basically asking: "I have a bucket with a hole in it; how long will it take me to fill it?" Quote Link to comment Share on other sites More sharing options...
MikeAlmogy Posted March 17, 2019 Author Share Posted March 17, 2019 19 minutes ago, ThomasPowers said: Without knowing anything about how it's going to be lined you are basically asking: "I have a bucket with a hole in it; how long will it take me to fill it?" Ok, i get that. After some calculations, it appears that i have a 210 liter furnace. or about 7.5 cubic feet. I will be using Kathal A1 wire. My power is 220V but i can go 3 phases if needed, i really prefer not to. What other info do you need? Quote Link to comment Share on other sites More sharing options...
Latticino Posted March 17, 2019 Share Posted March 17, 2019 As noted on this site http://www.joppaglass.com/elements/mainelpg.html you need additional information regarding temperature and insulation. I use his book which has a great calculator for power requirements as well as coil design. You can sometimes get away with single phase, but a kiln that size will need a large circuit breaker and feed wire to push the power required out to the elements. I don't know how things work in Israel, but demand charges may come into play as well as usage charges. In any event I urge you to hookup with an electrician for the wiring, at least, and see if you can find an electrical engineer to help you with the design and controls. Quote Link to comment Share on other sites More sharing options...
MikeAlmogy Posted March 18, 2019 Author Share Posted March 18, 2019 Thank you. I know all the additional info, i just did not think it was necessary. An electrician will look at it after i finish, especially if i will need to use 3 phase. However, i do have this furnace electric circuitry, it is just that the entire furnace got totaled on the move and i need to rebuild it. I can just copy but i want to understand and improve whenever i can. BTW, 200+ liters are calculated from the internal dimensions of the clear space. Now thinking of it, when i heat the furnace to X degree i also heat the isolation material. Meaning that the dimensions are way way bigger. No? It appears that 3 phase furnace is a must. xxxxxxxx Quote Link to comment Share on other sites More sharing options...
DRoberts Posted June 27, 2019 Share Posted June 27, 2019 i hit 2300F without any problems using 18G kanthal a1 in my 220V furnace. I calculate on the short side for coil length and fine tune input voltage with a 10,000w voltage regulator. Voltage regulator makes the resistance calculation very forgiving and greatly improved pid controller temp variance. my build https://davidproberts.com/diy/2300f-heat-treat-oven/ Quote Link to comment Share on other sites More sharing options...
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