"Custom" Kiln, Needs Better Elements.

[OVMI_Designs]

Hello,

I have an older kiln with 3" Brick, and 4 side wall elements. It is a Cone 8 kiln. It has always seemed under powered to me when firing to cone 6, even with new elements. It had a kiln sitter (which I used to fire with), but I did a custom upgrade with a Bartlett Genesis Mini kiln controller and all necessary relays and wiring. The current specs of the kiln are as follows:

-Wired into a 240v / 30 amp circuit

-5760 Watt Kiln with 4x 40 ohm (I think, totaling 10 ohms when wired together) elements @ 24 amps max. The 4 elements are wired in parallel. 

All the wiring in the kiln and custom kiln controller is rated for 30 amps. I am wondering if it would be possible to put in a higher powered element, while still maintaining the 30amp circuit. I was thinking something along the lines of:

-6240 Watts with 4x 37 ohm elements (9.25 when wired together) @ 26 amps max. This would still leave more than 10% head room on the 30 amp circuit. 

Do you think this is feasible and makes sense? Will an 8% increase in power make a difference on reaching cone 6? If so, who can I go to to get the elements?

 

[neilestrick]

1 minute ago, OVMI_Designs said:

Will an 8% increase in power make a difference on reaching cone 6? If so, who can I go to to get the elements?

Yes, it will make a difference. Not a ton, but it will definitely help.

 

1 minute ago, OVMI_Designs said:

This would still leave more than 10% head room on the 30 amp circuit. 

Code requires that kilns be on a circuit that is rated 25% greater than the draw of your kiln. So while all the internal kiln wiring will still be fine at 26 amps, you'll have to upgrade the service line and power cord to 35 or 40 amps in order to be up to code. If you're going to do that, I'd go ahead and bump up the  draw to 28 amps. Euclids.com can probably make what you need.

What sort of element life do you get- how many firings before they need to be changed? Does it struggle to keep up with a Medium speed firing profile?

I'm guessing your kiln is 18" wide and 22.5" tall (interior)? If it's only 18" tall interior, then it should be rated for cone 10 at those specs.

[OVMI_Designs]

Ah didn't realize you need 25%, which makes sense as the way the kiln is currently setup.

The kiln is indeed 18 wide by 22 tall interior. Also I double checked and it is 2.5" brick, not 3".

It is incapable of doing at Medium speed firing. I actual had to lower the top temp on my custom firing schedule from 2200 to 2150 with a longer hold and slower ramp. Ramp from 2100 to 2150 is 60/hr. I watch a cone through the peephole when firing. It takes like 13.5 hrs to reach cone 6. I think I am only getting about 40 to 50 firings before I start having issues. Part of the issue is a 5volt drop when under load in the circuit. 

The wiring from the breaker to the kiln is 8/3 copper, so I could potentially put a larger breaker in the box, and upgrade the kiln wiring. My other concern is that the house is a 100amp circuit. Do you think it could handle a larger draw?

[Mark C.]

#8 wire can handle a 40 amp curcuit breaker. 

Your house 100amp  service question depends on what other loads you have . The big ones are motors and heaters-like a well pump or a electric heater going down to electric dryer or washer motors-whats do you have needed the most power-forget about lighting loads

More info is needed to answer that question as to what your loads are in the house?

[OVMI_Designs]

Heating, Water Heater, and Oven is gas. Washer and Dry is electric. We have Central A/C. Fridge, Dish Washer, and Water Cooler are the other "larger" items in the house.

[neilestrick]

It'll probably be fine, but you'll have to add up the draw and see what can be running while the kiln is on. Might not be able to do laundry while firing.