110VAC Heat Treat Oven

Big Smitty

Big Smitty

Joined
Aug 30, 2007
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I need some help from some of the resident experts on heat treat ovens. I have read some of the posts on building HT ovens and most of them indicate 220VAC. Is there any way to build a reasonably fast HT oven the runs off 110VAC. I am trying to not have to run a 220VAC amp service to my workshop. I am looking to build a 6" X 4" X 15" oven. I understand the need to have a HT oven that heats quickly and just need to know if it can be done at the lower voltage. If anyone has any good directions/information please post. Thanks for your help!
 
I had a 120V heat treat oven with a chamber about 3" x 5" x 10". It would get to 1950 degrees in a little under 4 hours.

Re-wire your shop.;)

Rob!
 
I suppose an unconventional approach would be to to get a DPST SSR and some big heavy extension cords, split your coils and drive them off of two seperate breakers. I have done stuff like that before running stage shows, pulling power from all over the place. Caveat, Don't do it if you don't know what you're doing. ANY electrical crossover could be a problem, full electrical isolation between channels is a must.

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rob how many amps does your oven pull. the math does not add up. evenheats small 220v 13.5" oven has 7 watts per square inch of fire brick surface and there 18" has 5.25 w/in^2 and thay heat fast. yours if getting 1200 watts would be 7.5 w/in^2. i have been thinking about making a small one 3"x3"x12" at 115v 1300w. thats 9 w/in^2, that will heat very fast.
 
The only way to have a fast electric at 110v is to have high amps.
Watts are power to make heat

P (watts)= I x E (Amps x voltage) so if you want a small fast 110 you need 30 amps to get any real wattage 110v x 30amps = 3300 watts. Problem is replacing the breaker won't work because you need a heavy wire to carry the amps around 8 gauge. This is a must. Wire size is a function of amps not voltage. A very thin wire will carry thousands of volts as long as the insulation is thick enough. Wire size must match amperage or it will heat up and melt the insulation (no matter how thick) and then fire. Insulation is to keep voltage from arcing. with a standard 110 line and 20 amps you can have 2200 watts max. If you had a very small chamber that was very well insulated you might get there fast. But, here is another problem there. The kanthal heating elements. You need room to install them and then you need to have room to put your piece without having it hit the elements and cause a electrical short.
 
There are 2 reasons for going 220V on HT ovens. As noted above the standard 110 outlet is 20 (modern, some older homes may still have 15) amps. It is quite uncommon to see larger amperage 110 only outlets in a home without custom wiring. If you are adding custom wiring, you might as well go 220 as the cost will be nearly identical.

In comparison, 30 and 50 amp outlets for 220V are common, as they are used for dryers, stoves, hot tubs, etc. So, not only does the wattage double by doubling the voltage, higher amperage is easy as well, further boosting the watts you can get into your oven.

Note that all of this applies to our US standard wiring, international wiring will vary as many places (Europe, Asia, some middle East, some Africa) use a 230V single hot line (typically 16 amp) as their standard for household wall outlets.
 
The Paragon HT that runs on 110V only takes 2.5 to heat up to soak at 1950 F. No problems at all.
 
if you have a smaller chamber you dont need tons of watts. you need a minumin of 4 watts per surface area of oven lineing.
 
JTknives said:
rob how many amps does your oven pull.
Click to expand...

No idea. I sold it a couple years ago in favor of the evenheat. I'm not sure it's all about watts per cubic inch. My old one - actually a dental burnout kiln - would get to 1500 or so fairly quickly but took forever to get to 1950. It was capable of a bit more because I once had it to 2000.

There have been threads here in the past about 120V kilns and I don't recall any really positive experiences for those doing SS blades.... but hey - maybe someone can figure out some extra efficiency.

Rob!
 
My 110v Paragon goes up to 1500 in about 40 mins. I don't know why yours takes so long. I have the 14" model with digital controls. I've taken it up to 1900 and I don't think it took much more than an hour to get there but it was a couple of years ago so I don't remember.
 
The size and wattage are all that matters in these cases. The larger 110V ovens take longer to get up to temperature and some kilns may never reach 2k+ because they lose the heat faster. It takes us about 90 min to get to 1950 with a sugar creek, the paragon should be even faster since it's a smaller chamber and similar wattage.

Get a smaller oven if you want to run it on 110V. I wholy oppose trying to run a 220V oven off of two 110V lines. If you'll go to that trouble, just wire in a legit 220V line.
 
As stated above my km 14 paragon will get to 1950 in just under an hour. I have no problems doing stainless in it. I run it on a standard 20 amp 110 volt outlet
 
all else being equal that would point to voltage drop in the slow one. When you are dealing with heating elements the difference in heat output between 107 volts, and 120 volts can be on the order of around 20%
There is a difference between household voltage in a house that is close to the pole transformer in a suburban neighborhood with clean wire connections and a good clean neutral to earth connection and, for instance a mall or urban apartment complex. My shop in Ithaca is 30 feet from the pole transformer and has nice new wires, and my wall voltage there is typically right around 118-120/ 236-240 year round. On the other hand the photolab I used to manage in a shopping mall had wall voltage of typically 107-109 with occaisional spikes and drops. The electric company typically considers 105-125 volts within normal range for a "110" outlet, they will however REALLY pay attention if you're suddenly not getting a 60hz sine wave!


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If you have to go 110 go narrow and under 16 inches and insulate the crap out of it.
My unit is 22o and has a layer of soft brick the an inch of kaowool on the outside that. It hits 1500 in 11 minutes and you can touch it anywhere on the outside for a long time even at 2000. It hits that in less than 20 minutes. It is 4.5" x 4.5" x 22" and uses 17.5 amps of 220. . It is not that hard to get 220 in your shop and it is great for so many things. I am running it to my grinder area this weekend.
 
Check your voltage coming in through the outlet. A few volts makes a difference in heat output. Most of the time I am getting 118 volts on my 110 outlets. During summer when everyone and their dog is running their airconditioners my voltage can drop to 108-109V. I notice that my kitchen stove, vaccums and everything else slows down. During these times it seems that my paragon takes another half hour or so to reach temperature.
 
Thanks for the response. I am not much of an electrician and really dont know what is required to run a 220 service for a HT oven. I have a 200 amp panel. I do have a buddy that is an electrician that can help me out. I was just wondering if there was a HT oven that would that would heat realitively quick and run on 110VAC. I guess that it doesn't sound like I can get the 110VAC to work based on your comments. Thanks for the feedback, I'll look up an electrician.
 
Hope i Didn't say that wrong. It will work... It just will not work well.

It's just not good to leave blades in the heat for many hours. You can preheat the oven and save some of that problem - but it will lead to other problems for you - such as blowing up envelopes from sudden heat exposure - or long re-heat times after opening the door.

To be honest, mine could probably reach 1950 in a little over 3 hours - workable - but not desireable.

Your electrician friend should be helpful. Maybe you can run the wire and save him some time so all he's charging you for is good advice. I think you'll be happy you upgraded to 220.

Rob!
 
Here's how I built my oven...


I took 11 of these:

100_dollar_bill.jpg


Stacked them together neatly....

...and oila! I had an oven!

:D

:foot:




I have heat-treated hundreds of blades in my 14" Paragon running 110v.

Works great!
 
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