Kiln advice
- Thread starter Sputnik 184
- Start date
sorce
Nonsense Rascal
Slow and low that is the tempo.
Sorce
Sorce
Sputnik 184
Mame
We removed the thermocouple for inspection. Hoping for a definitive answer but as you can see it isn’t charred and crumbly. There may be a couple of fine cracks visible but I’m not quite sure what I’m looking at.
Any ideas?
penumbra
Imperial Masterpiece
Did you take a picture of the thermocouple?
Sputnik 184
Mame
Sorry. Failed to attach them.
Attachments
HorseloverFat
Squarepants with Conkers
Hehe... Your thermocouple is different than mine. 
Lo estas Bien, en MI ojos...
But I ALSO can't see the picture well enough to notice any fine crack, like you were describing.
Lo estas Bien, en MI ojos...
But I ALSO can't see the picture well enough to notice any fine crack, like you were describing.
Sputnik 184
Mame
The areas I’m seeing as cracks are where there is a slight change of direction and there is a very small bit of metallic showing on the tip. Presuming that’s not normal? This is a type S thermocouple.Hehe... Your thermocouple is different than mine.
Lo estas Bien, en MI ojos...
But I ALSO can't see the picture well enough to notice any fine crack, like you were describing.
penumbra
Imperial Masterpiece
I have replaced dozens of these type s thermocouples. Yours looks ok but only a continuity test will tell for sure.
Sputnik 184
Mame
Continuity looks okay. Guess we’re now waiting for a resistance figure from Cromartie to test the elements unless you have any other suggestions?
penumbra
Imperial Masterpiece
That is appropriate.
Sputnik 184
Mame
Really grateful for your help.
Just checked the resistance on the elements. There are 3 elements in series. Using the 200 on the ohm scale we get 6 for each individual element and 17.4 for the total 3 elements. I don’t know whether this gives you any clues without a manufacturers resistance but it seems low so guess that’s good? Kiln is 13 amp 230 volts approx 3kw and expected 1260C max temp.
penumbra
Imperial Masterpiece
Its been a few years since I rebuilt a kiln, but we looked up the resistance as we needed to per kiln. Many times, if not most, elements were replaced according to clients performance or log and verified visually.
Sputnik 184
Mame
We waited for a response from Cromartie and when no responses to our email came we phoned their technical department. They were pleasant and reasonably helpful but refused to divulge the optimal resistance so no joy there. After testing for possible power supply drop off between the house and the garage where the kiln is housed we decided to run a 16amp cable between them to ensure it wasn’t a power issue. 13 amp was a bit borderline. It has faulted again and I’m out of ideas.
penumbra
Imperial Masterpiece
I think it is odd that the manufacturer will not give you vital information on your kiln. I see three possible choices, although they are the most obvious choices, there could be others.
- I know you have kiln repair specialists. When I worked for the Kiln Doctor, we frequently had people drop off kilns for evaluations. We had to run down all the particulars and we would give an estimate on repair. The estimate was free unless it required a road call.
- You could replace all the parts suspected yourself. Often a visual inspection of the elements is enough, but not always. If elements are sagging badly, they need replacing. There are other visual clues as well.
- Get a new kiln.
II am curious, are you saying your kiln only draws 13 amps? That is less than a hair dryer. These are generally small table top hobbyist kilns. They are not very durable as a rule.
My smaller kiln draws 30 amps and uses a 40 amp wire (cable). My larger kiln draws 48 amps and uses a 60 amp wire. This seems like a lot but it is standard procedure. If all the elements come on at once, a kiln can exceed expected amperage under some circumstances.
I hope you can work it out my friend as I know professionally that it can be an effort with sometimes less than desirable results. Often kilns came into us that required so much repair investment that they were retired.
- I know you have kiln repair specialists. When I worked for the Kiln Doctor, we frequently had people drop off kilns for evaluations. We had to run down all the particulars and we would give an estimate on repair. The estimate was free unless it required a road call.
- You could replace all the parts suspected yourself. Often a visual inspection of the elements is enough, but not always. If elements are sagging badly, they need replacing. There are other visual clues as well.
- Get a new kiln.
II am curious, are you saying your kiln only draws 13 amps? That is less than a hair dryer. These are generally small table top hobbyist kilns. They are not very durable as a rule.
My smaller kiln draws 30 amps and uses a 40 amp wire (cable). My larger kiln draws 48 amps and uses a 60 amp wire. This seems like a lot but it is standard procedure. If all the elements come on at once, a kiln can exceed expected amperage under some circumstances.
I hope you can work it out my friend as I know professionally that it can be an effort with sometimes less than desirable results. Often kilns came into us that required so much repair investment that they were retired.
Sputnik 184
Mame
We couldn’t believe they were so unwilling to disclose the resistance figure. A couple of other possible problems were suggested in addition to elements and thermocouple. One was the vague possibility of a controller problem and the other was failure of the mercury switches which operate when the lid is closed.There doesn’t seem to be any way of testing the switches but we are going to bridge them out to see if this makes a difference. Will also open the controller to see if there are any obvious signs of damage. I can’t easily get the kiln to a specialist and a call-out will be pretty expensive.
As to the power supply it is a hobbyist kiln and the manufacturer says at 230v and 13amps it is capable of reaching 1260C. The new 16amp cable definitely seemed to make a difference to the speed of firing until it faulted again.
Going back to the element problem is the following too simplistic? The kiln is rated 230v 13amp (nominally 3kw). We know power= volts x amps so 230x13=2990W.
We also know resistance= voltage squared divided by power. So resistance = 52900 divided by 2990 = 17.69 ohms.
My kiln has 3 elements in series. Measured resistance was 17.5 ohms which would seem pretty close.
One day I’ll getter a bigger and better kiln but this is the best I can do with the circuitry available at the moment.
Thank you again for your time and input on this problem.
As to the power supply it is a hobbyist kiln and the manufacturer says at 230v and 13amps it is capable of reaching 1260C. The new 16amp cable definitely seemed to make a difference to the speed of firing until it faulted again.
Going back to the element problem is the following too simplistic? The kiln is rated 230v 13amp (nominally 3kw). We know power= volts x amps so 230x13=2990W.
We also know resistance= voltage squared divided by power. So resistance = 52900 divided by 2990 = 17.69 ohms.
My kiln has 3 elements in series. Measured resistance was 17.5 ohms which would seem pretty close.
One day I’ll getter a bigger and better kiln but this is the best I can do with the circuitry available at the moment.
Thank you again for your time and input on this problem.
penumbra
Imperial Masterpiece
I overlooked your 230 v. A 13 amp kiln in the states would be 115-120v. Also only high end kilns use mercury switches here. It is a completely unnecessary "safety" protocol.
I wish I could be of more help, but even on this side of the pond, kilns are almost never repaired by correspondence or over the phone.
I wish I could be of more help, but even on this side of the pond, kilns are almost never repaired by correspondence or over the phone.
JeffS73
Shohin
Sputnik, how long is the 16a cable? 13a sockets are on 2.5mm cable and a 32a breaker. A long 16a cable still might not be adequate.
Besides this, you were getting to temp and now you aren't, so something has changed.
Have you got access to the relay in the controller? Apparently if these get hot there may be a drop in the current it can pass. Secondhand info from a ceramic arts query of a similar nature. See https://hotkilns.com/support/pottery-kiln-trouble-shooting-actions/check-power-relay
Has your kiln got bigger gaps or newly cracked bricks?
I would in turn change thermocouple, relay, elements and then maybe try for an aftermarket WiFi PID controller from ebay. I know you don't want to change parts unnecessarily tho.
Also, what cone were you aiming for? It looks like the kiln did the necessary heartwork (all cones down), so perhaps by eyeballing temp & time with that orton info you can get the desired result. Best of luck!
Sputnik 184
Mame
I know this is a tricky one especially at a distance and I’m really grateful for your efforts to help. I will continue to post my progress and if you have any further thoughts I would love to hear them.
Sputnik 184
Mame
Thanks for all your suggestions.
The updated power supply is4mm from a 32amp breaker. The cable is about 30m which I believe should be adequate for more than 16 amps. All connections are now 16 amp plugs and sockets including the kiln.
One of the next jobs is to open the controller and have a good look at it. Thanks for the links concerning relay.
No problems with the bricks and the lid is a good seal.
Very reluctant to start a chain of component replacement without some further clues as it could cost more than it’s worth.
You may be right about cones v time to achieve the heat work but if the fault is getting worse this wouldn’t be reliable.
Sputnik 184
Mame
Just had to post to tell you I finally had a successful firing last night. After weeks of puzzling and testing we decided to replace the 13amp elements with 16amp ones. The kiln reached the desired temperature and faster than it has before. Still waiting for it to finish cooling to inspect the pots within but so far it would seem to be a success.
