heat treat oven elements

T

tnkid

Joined
Nov 30, 2015
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Hey guys first post here and I need some help. I'm building a heat treat oven, that will be 220v and I understand everything about building it. But I've read you need two elements, and I cant figure out if I need two 120v elements or two 220v. Thanks
 
Well, it depends - either will work. Parallel the 220vac elements and series the 120vac elements.
 
Unless you have a massive oven, you should be fine with ONE element. Measure you channel using some string/rope, and then order an element in that size range. When I built mine, I bought a "pre-wound" element that needed to be stretched, and as I recall had a pretty good range of lengths that it could work for.

220VAC will be better and heat faster.
 
Assuming you have 220VAC available, you want to build for 220VAC.

You can use either a single 220VAC element, two 220VAC elements in parallel, or two 110V elements in series.

If you are following the Andy Gascoigne plans that have been in various places on the web for many years, Andy used two of the 110V elements in series to run on 220V. BCS, the supplier of his elements, subsequently started selling 220V elements as well and this has caused some builders some confusion. The 220V element is twice as long as the 110V.

Personally, I always use two 110V elements connected in series: one element in each of the side walls. Using two 220V elements connected in parallel could work, but would need twice as much groove length to accommodate the longer elements. If I have the wall area available for longer elements, I use it to go for thicker element wire to give longer element life.
 
Thanks for the replies. I am following Andy plans, and mine in going to be a bit longer. So I'm going to with two 120v since that's what budget casting supply carries.
 
Just for info, I have built HT ovens to more-or-less that design with both 18" and 22 1/2" chambers, using Thermal Ceramics JM23 IFBs.

Both sizes of oven were tested to 1205 degC (2200 degF), though the longer one took 90 minutes to get there from cold.

My elements were nominally 13A and I measured the maximum current drawn at 12.8A with a 234VAC mains supply, measured at the control box supply terminals (UK domestic mains is nominally 230V and we use 13A fused plugs), for 2995 Watts.

I have been told the K23 bricks are slightly lighter than the JM23s and therefore provide slightly better insulation and slightly faster heat-up.
 
either works , power is what you should be focused on for element ratings. I normally go for 240 volts ... 230 , 220 what ever you guys rather ... because of lower current draw for the same rated element.

cheers

grumpy_grinder , you're grumpy industrial electrician friend
 
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