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Kiln Troubles - Ward / Skutt / Tetlow (All 15 Amp)


Indra

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Hello there,

 

As I live in a rural area I'm having trouble finding someone who is both qualified and available to look at doing repairs on my hobby kilns, so I've been very much thrown in the deep end.

 

I've been working in ceramics for about a year now, making mostly jewellery. I've experienced several challenges with my Ward HPF4 hobby kiln, the most recent of these is unresolved. My electrician (let's call him Richard) initially installed 15 amp power (for a 15 amp kiln) and I ran a dozen or so firings with no problems. After one firing I noticed a slight melted flare on the electrical power point plug holes and next time I fired up there was nothing happening. Richard then upgraded the power point and kiln cord to 20 amp, admitting that he should have thought to install 125% of the required amps to start with. He had to replace the contactor at that point, which looked like it really should have gone long ago. I did a successful bisque firing after that and I noticed that the kiln was much quieter. Then the next time I went to do a glaze firing I found that every time I'd turn the kiln on, the fuse switch in the fusebox would trip. Richard did look at the kiln again but didn't want to get too involved. I haven't been able to get anyone else to look at it so far. My frustration has driven me to research a little and, to my surprise, I'm starting to get a bit interested in the components and wiring. Yesterday I removed the wiring box from the main body of the kiln so I could have a look at the concealed side of the simmerstat - just looking generally for abnormalities in the wiring and connections. Well, I found that the connections are pretty rusty and the wires look scorched - hardly surprising since it was wedged right against the outer wall of the kiln. I am in the process of obtaining a replacement (a TYJ6333 to replace the existing TYJ02B) and am fairy confident that I can fix it myself. I imagine it's a simple case of replacing the wire connections from one unit to the other and I notice they are fully labelled, which helps. Should I solder the connections or is this not generally done? Also, I'm thinking of cutting a square of fibre cement to fit in between the simmerstat and the outer wall of the kiln (if it will fit). Does this seem reasonable? Or can anyone suggest a superior material for this?

 

In the meantime... out of desperation I bought (cough) a couple of other second hand kilns. One (a Skutt test kiln) was damaged in transit and I am repairing it (waiting for parts). It seems to be just a bent sensing rod in the kiln sitter and possibly a replacement plunger & button. I think I can do that.

 

Finally - the other one is a Tetlow K4A - just like the one pictured. post-80483-0-65062300-1479186849_thumb.jpg It has an energy regulator dial, an on/off switch and a thermostat dial and temperature reading display. I have fired this kiln three times now.

 

1st firing - The on/off switch switched itself off after about half an hour. I angled a stick at it to keep it 'on' and the firing progressed. The kiln gained heat rather quickly. For instance, it was already at 560'C (1040'F) when I turned it up to 400'C (752'F), up to 720'C (1328'F) when I turned it up to 600'C (1112'F), up to 840'C (1544'F) when I turned it up to 800'C (1472'F). Once about 850'C (1562'F) was reached, it shut itself down, as in... the 'on' button was still on, the green light was shining on the thermostat but temperature had dropped and the kiln wasn't making any noise. The 'on' switch no longer seemed to work.

 

2nd firing - After replacing the on/off switch using only pliers and very little expertise I got the kiln firing up again. It steadily approached 800'C in a similar fashion and once again did not fire much beyond that.

 

3rd firing - I re-did the on/off switch connections with proper crimpers and then soldered them. I fired the kiln up again (empty this time, just for something different) - this time all the way up to high. At around 850'C (1562'F) was reached, it shut down again. Dials and green thermostat light still on but no noise and no heating going on (It's the same when I turn it back on). I'm pretty sure that after this final firing the red light display connected to the simmerstat/energy regulator dial no longer illuminates as it did before. Also, the on/off switch is kind of stuck on. 

 

Is it possible that the on/off switch is not as generic as I think it is and just needs to be properly replaced with a Tetlow brand switch? I had a good look inside and the electrics overall look fantastic. Today I had another look and did notice something irregular. I just added a picture of some of the wiring in this actual kiln. post-80483-0-93131100-1479191932_thumb.jpg Can you see a bit of darkness at the connection of the top red wire? Also a slight burned look to the casing in the middle of the front vertical edge of the simmerstat? I'm thinking that if I replace the simmerstat it might all just work again. It currently has a TYJ 6336 simmerstat but I'm thinking that any of the TYJ type simmerstats will work as long as it's 15 amps. Will I have to replace that one wire as well? Or more than one? If so, how do I find out what type of wire I'd use? I'm thinking that if this doesn't work I'd be looking at replacing the thermocouple. I would welcome any feedback or musings on my situation.

 

Best regards,
Indra

 

 

post-80483-0-65062300-1479186849_thumb.jpg

post-80483-0-93131100-1479191932_thumb.jpg

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First, all kilns must be on a breaker/fuse that is 125% of the draw of the kiln. So your 15 amp kilns should be on 20 amp breakers/fuses. That won't affect the ability of the kiln to get to temperature, but it is a safety issue. Fix that before firing again. I need to re-read your post before I offer any suggestions. Lots of info to digest here....

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Neil,

I am about to call an Electrician in Montana about wiring for my kiln shed. My largest oval is 90 amps. So should it have 120 breaker? It has a 100 amp right now.

My other kilns are smaller. I 'll have to check their amperage. I want to get separate service for the shed. Fortunately is sits directly below the electrical source in the alley.

 

Marcia

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Neil,

I am about to call an Electrician in Montana about wiring for my kiln shed. My largest oval is 90 amps. So should it have 120 breaker? It has a 100 amp right now.

My other kilns are smaller. I 'll have to check their amperage. I want to get separate service for the shed. Fortunately is sits directly below the electrical source in the alley.

 

Marcia

Yes as the 90 amps at 125% is 112.50 amps so 120 is plenty.

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First, all kilns must be on a breaker/fuse that is 125% of the draw of the kiln. So your 15 amp kilns should be on 20 amp breakers/fuses. That won't affect the ability of the kiln to get to temperature, but it is a safety issue. Fix that before firing again. I need to re-read your post before I offer any suggestions. Lots of info to digest here....

Thanks Neil,

 

My electrician assures me that 20 amp breakers were installed at the same time the cord/plug were upgraded to 20 amp.

 

Indra

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 (Should I solder the connections or is this not generally done? Also, I'm thinking of cutting a square of fibre cement to fit in between the simmerstat and the outer wall of the kiln (if it will fit). Does this seem reasonable? Or can anyone suggest a superior material for this?)

soldering is not generally done crimp connectors are more common

​Use ceramic fiber to insulate(its flexible and soft-and cut with scissors)-You may be calling this fiber cement as english is a bit different down under

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