High Bridge Pottery Posted February 12, 2023 Report Share Posted February 12, 2023 I am surprised pottery crafts said they wouldn't do it, probably just being lazy as they don't have the specification on file. The few places I know who would probably wind them for you are https://www.kilncare.co.uk/elements https://www.kilns.co.uk/kilns/kiln-elements https://www.cromartiehobbycraft.co.uk/Catalogue/Ceramic-Kilns-Electric-Kilns-Pottery-Kilns/Kiln-Spares-Kiln-Elements/Kiln-Elements-Element-Wire-Connectors Ceramics.np.04, Callie Beller Diesel and Hulk 3 Quote Link to comment Share on other sites More sharing options...
Ceramics.np.04 Posted February 12, 2023 Author Report Share Posted February 12, 2023 10 hours ago, High Bridge Pottery said: I am surprised pottery crafts said they wouldn't do it, probably just being lazy as they don't have the specification on file. The few places I know who would probably wind them for you are https://www.kilncare.co.uk/elements https://www.kilns.co.uk/kilns/kiln-elements https://www.cromartiehobbycraft.co.uk/Catalogue/Ceramic-Kilns-Electric-Kilns-Pottery-Kilns/Kiln-Spares-Kiln-Elements/Kiln-Elements-Element-Wire-Connectors This is brilliant. THANK YOU! Could cracks in the fire bricks cause the firing to slow down significantly? They don't seem to be going all the way through but there is a pretty big one running across the top and I've just found one down the back when I took the cover off to take photos Photos of the back: ...and cracks: I have some high temp cement to fix these. Would it be worth trying before getting new elements or will it not make that much difference? High Bridge Pottery 1 Quote Link to comment Share on other sites More sharing options...
High Bridge Pottery Posted February 12, 2023 Report Share Posted February 12, 2023 (edited) Thank you for the photos. Looks like an interesting kiln, is that just bare copper going in between the elements? Not seen anything like that before. What is that black box they are connecting to? I don't think the cracks are letting out much heat to slow down your firings and would imagine the peep hole on the front lets out more. At least the wiring is simple as they are all in series. The only tricky part is working out if the floor elements are a lower resistance to the side wall. I will have a think if there is an easy way to test it but from the element photos you posted the floor element coils do seem to have bigger spaces in between each rotation of the wire than the side wall. Do they look like that in person as it's a little hard to tell from photos? Looking at it a bit more I am confused on how the neutral is getting back, the main wire just seems to have two live wires coming out. Is the power coming in through the thinner cable and the controller is the thicker cable? That makes a bit more sense. Edited February 12, 2023 by High Bridge Pottery Quote Link to comment Share on other sites More sharing options...
neilestrick Posted February 13, 2023 Report Share Posted February 13, 2023 The cracks shouldn't affect heat loss. When making elements, they'll need to know the diameter of the coils and the resistance of each element. Where this kiln gets more complicated is that you need the straight section in the middle of each element rather than one continuous coil. I would measure the resistance of a few of the individual wall elements (top, middle, bottom) and see if they're all the same. They may or may not be, just depends on how they did it. Also measure the resistance of the floor elements. They may have the same resistance as the wall elements but they're just spaced differently, or they may be a different resistance. Since they're all wired up in series, the elements have likely worn at about the same rate, so even if they're no longer reading like new, whoever makes the elements should be able to math it out to get accurate numbers on what they should be based on the ratios they're reading now. To get the straight sections made correctly, I would send a wall element and a floor element to the maker. Once you measure the resistance of all the elements you can math out the amperage draw and see how far off it is from the information on the serial plate. Quote Link to comment Share on other sites More sharing options...
High Bridge Pottery Posted February 13, 2023 Report Share Posted February 13, 2023 (edited) 6 hours ago, neilestrick said: Once you measure the resistance of all the elements you can math out the amperage draw and see how far off it is from the information on the serial plate. Will you get the right resistance readings without taking off the connecting wires? I was worried that you could read the wrong resistance but I have normally been working on parallel elements. The only way I could think of is to test the voltage drop across each element but that would mean testing while the kiln is on. After a bit more searching and testing on my own kiln it does seem like you only need to disconnect wires in parallel circuits as there's only one path in a series circuit. Means it should be fine to test the resistance of each element without taking off the wires Even if the floor elements are a different resistance they probably wont be too far off from each other. The total resistance should be 240volt / 15 amps = 16 ohms If all the elements were the same resistance then 16 ohms / 10 = 1.6 ohms for each element. At a guess maybe the floor elements are 1 ohms each and the side wall would all be 1.75 ohms each Edited February 13, 2023 by High Bridge Pottery Quote Link to comment Share on other sites More sharing options...
Ceramics.np.04 Posted February 13, 2023 Author Report Share Posted February 13, 2023 @neilestrick @High Bridge Pottery At the risk of being the cause of a few exasperated sighs and head shakes: most of this is going completely over my head. I am completely out of my depth...but also stubborn and ready to learn. 14 hours ago, High Bridge Pottery said: Looks like an interesting kiln, is that just bare copper going in between the elements? Not seen anything like that before. What is that black box they are connecting to? I was worried you were going to say that. Yes, it is just bare copper (which even I thought was a bit odd) and, once I'd taken the cage off the back and cleaned it all up a bit, everything about it looks pretty old and tatty. I've tried to take some photos in sequence so the wiring might make a bit more sense: and then some close ups of the two...er...connect-y thingies: High Bridge Pottery 1 Quote Link to comment Share on other sites More sharing options...
Ceramics.np.04 Posted February 13, 2023 Author Report Share Posted February 13, 2023 (edited) @High Bridge Pottery As for the coils and the spaces in between the rotations, they don't seem to be very uniform. I just tried to measure the space between and they were all different and then seem to get more bunched up towards the back I took some (really poor quality) photos to try and show the side vs. the floor: Floor: Walls: Edited February 13, 2023 by Ceramics.np.04 Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted February 13, 2023 Report Share Posted February 13, 2023 Suggest: Just count the number of complete coils in the entire length, measure the length. This can be done on several just to confirm they are the same or not. Euclid can then distribute evenly once a wire size and resistance value is picked. Ceramics.np.04 1 Quote Link to comment Share on other sites More sharing options...
neilestrick Posted February 13, 2023 Report Share Posted February 13, 2023 The bare copper jumpers are an odd way to do it, and not necessary. Instead, just leave the element pigtails long, bend them to meet up and overlap about an inch, and put a connector on them. Ceramics.np.04 1 Quote Link to comment Share on other sites More sharing options...
High Bridge Pottery Posted February 13, 2023 Report Share Posted February 13, 2023 (edited) They look about the same to me even though some are not very even. Lets hope they are all the same resistance and the floor just have a bigger hairpin. Do you have a multimeter to test the resistance of each element? You would need to turn the dial to select a low resistance setting. Depending on the type it could be 200 Ω or lower like 20 Ω but the lower the better as they will only be measuring around 1-2 ohms. I have drawn a basic picture to give you an idea You will have a black and red probe and put one on each leg/tail of the elemet to get the value. Make sure you turn off the kiln isolator switch first. Still not sure what that black box is doing, I thought maybe it is the relay but then the controller has the relay inside so I guess it is another kind of safety switch? I don't think the bare copper is a problem but as Neil says you can just connect the element tails together with a connector if they are long enough. Edit: maybe an actual picture could help Edited February 13, 2023 by High Bridge Pottery Ceramics.np.04 1 Quote Link to comment Share on other sites More sharing options...
Ceramics.np.04 Posted February 19, 2023 Author Report Share Posted February 19, 2023 @High Bridge Pottery I've measured the resistance and they're all the same (sides and bottom), around the 2/2.5 mark... the number kept fluctuating quite a bit but 2.2 seems to be a thing(!?) High Bridge Pottery 1 Quote Link to comment Share on other sites More sharing options...
High Bridge Pottery Posted February 19, 2023 Report Share Posted February 19, 2023 (edited) Good to know they are all the same besides the hairpin length. It can be tricky to get an exact read on these things. Having them all at 2.2 ohms means the kiln is drawing just over 10 amps on 240v supply so I am not surprised it wont reach top temperature/get there slowly. I would maybe confirm it with whichever company but the basics should be voltage/amps = resistance so 240/15 = 16 ohms for 10 elements in series and 1.6 ohms for each element. Edited February 19, 2023 by High Bridge Pottery Ceramics.np.04 1 Quote Link to comment Share on other sites More sharing options...
Ceramics.np.04 Posted March 6, 2023 Author Report Share Posted March 6, 2023 @High Bridge Pottery So, bearing in mind that I have no idea what I'm talking about, does that mean that the elements need more power than I can give them from the mains? It's not that they're worn out, it's that they're industrial strength (?) elements? I need to get new ones made up with a lower resistance? I hope I'm understanding at least some of this right...! Thank you SO much for all your help so far. Quote Link to comment Share on other sites More sharing options...
High Bridge Pottery Posted March 6, 2023 Report Share Posted March 6, 2023 They are definitely worn out, you need to get new ones made up with a resistance of 1.6 ohms per element. They will have been that resistance to start with but over time they wear out and increase their resistance. It's not that you can't supply enough power to the kiln it is just that as they wear the resistance increases and the amps will decrease meaning you are getting less power to the kiln. Amps are just a function of voltage divided by resistance, we can't change how much voltage comes in the wires so by changing the resistance you can increase how many amps the kiln will draw. It's one of the reasons we have breakers and fuses because things can go wrong and many more amps can be supplied through wires not rated to handle that power if the resistance drops for some reason like a short circuit. Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted March 6, 2023 Report Share Posted March 6, 2023 (edited) 16 minutes ago, High Bridge Pottery said: They are definitely worn out, you need to get new ones made up with a resistance of 1.6 ohms per element. You might want to pick an original wattage to match and establish the new resistance to the original design using his current operating voltage. This way he will have the amount of designed heating energy available. When electric kilns wear by about 10% they usually have trouble making top temperature. In this case since this is a very small kiln electrical and load, bumping this to 4000 watts likely has no effect on his current wire and breaker and could provide additional room for future wear. Just a thought. Edited March 6, 2023 by Bill Kielb High Bridge Pottery 1 Quote Link to comment Share on other sites More sharing options...
High Bridge Pottery Posted March 6, 2023 Report Share Posted March 6, 2023 That's true you could make them all 1.44 ohms instead on 240v and get 16.6amps and a 4kw kiln instead of 15 amps and 3.6kw. Looks like the controller has a 30amp relay so that shouldn't be a problem on the relay either and give you additional room for wear. What size is the breaker on the kiln? 16.6amps +25% does just take you over 20 amps but it might be bigger anyway. Bill Kielb 1 Quote Link to comment Share on other sites More sharing options...
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