HT Oven Help

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buckaroo2219

Joined
Feb 13, 2013
Messages
47
Having some issues with my oven I built. It will ramp up to 1000 in about 30 minutes but really slows down and struggles after that. I am leaning towards the element size but really have no clue.
 
Does sound like element size which with its length controls its wattage which controls its ability to heat. Possible its insulation, does it get hot on the outside? Is it 220 or 110? what are the dimensions of the heat chamber? Do you know what size and length element you have? Somewhere in the stickies there is and explanation on elements.
 
I would re-calculate the element size you used first to be sure you put in the right size.
Is it running on the right current for the length/gauge you picked?
Are you reading in F or C?
What insulation did you use?
How big is the chamber?
 
Here are the numbers. K23 brick. Single layer all sides. I also use 2 to 4 inches of vermiculite in all sides. Outside dies get warm but only after a couple hours.
Chamber size is 14 deep 5 wide 4.5 high.

220volts 20amp circuit. Usind a programmable PID with 20 amp ssr.

Could are A1 kanthal. 240 vac 13amp 3120 watts. 17 awg. Outside dia is .280. They are designed to be stretched from 60 to 120 inches. I have them at the minimum of 60. They are wired in series.
 
Sounds like you are reading C instead of F. Did it with my homemade and it wouldn't go above 1350. Actually was 2350 F .
TJ
 
If I've understood correctly, it sounds like you have 2 elements, each designed for 240V, wired in series on 240V. Each element will therefore only see 120V.

Voltage per element will be half design. Current per element will also be half design. Power will be one-quarter design.

If they've not got seriously hot and gone brittle, can you rewire so you just have the one element at 240V? It will double the power input you currently have.
 
I do have two. One on each side of the oven. One leg of the 220 is connected to one end of coil one. Coil one is laid in channels on the wall. The other end of the coil one is connected to an end of coil number two that is placed in channels on the opposite wall. The other end of coil two is connected to the second leg of the 220 power coming in.

These are the specs for the elements. I am using 2 connected together.
•Material: Kanthal A1 Wire
•Maximum Temperature: 2300°F
•Power: 240 Vac, 13 Amps, 3120 Watts
•Wire Size: .046", (17 AWG)
•Unstretched Length: 41"
•Minimum Operational (Stretched) Length: 60"
•Maximum Stretched Length: 120"
•Coil Outer Diameter: .280"
•Pig Tail Length: 1-1/4"

So if I understand what you are saying is that I should only be using the one and it should be stretched so it covers both wall.
Thank you timgunn1962 for all the info.
 
buckaroo2219 said:
Here are the numbers. K23 brick. Single layer all sides. I also use 2 to 4 inches of vermiculite in all sides. Outside dies get warm but only after a couple hours.
Chamber size is 14 deep 5 wide 4.5 high.

220volts 20amp circuit. Usind a programmable PID with 20 amp ssr.

Could are A1 kanthal. 240 vac 13amp 3120 watts. 17 awg. Outside dia is .280. They are designed to be stretched from 60 to 120 inches. I have them at the minimum of 60. They are wired in series.[/QUOTE]



That could be it. At 240 volts and getting 3120 watts, the resistance should be 18.5 ohms. Disconnect the power wire at the SSR and read from there to the other end of the coils. If you wired two 18.5 ohm coils in series you will only get 1600 watts.
Click to expand...
 
You've got it.

Are you by any chance more-or-less following Andy Gascoigne's design from British Blades?

If so, I think that it is quite easy to make the mistake. I gather that he got his elements from BCS and used 2-off 110V 13A elements, which were all they listed at the time, so it was obvious what was needed. He connected them in series for 230V UK mains.

BCS then started selling 13A 220V elements and Andy's original write-up became ambiguous.

Regards

Tim
 
Thanks everyone for the help. I see now what is wrong. I did follow the plans on British Blades. BCS also has the plans available.
 
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