My new oven begins...

[chromeitout]

Thought I'd say hello and thanks to everyone on this forum for inspiring me to add powder coating to my existing custom auto shop. I've been pc'ing for a couple of months (mostly on scrap parts) and have pretty much got the basics down. Now to the point... Time for a bigger oven!
My plans are to build an oven 8'wide x 8'tall x 4'deep so that I can cure chopper frames an sub-frames for old cars. I'm still searching this forum for info. on all of my parts, so no questions right now, but I'll post back here when I run into trouble. I bought my 22 metal studs for the frame and will start on it ASAP. It may be a slow go due to the fact I am super busy already, but I'll keep you posted of the progress. Again thanks to the users of this forum for the inspiration and wealth of information, and to Caswell for their great products.

[chromeitout]

Re: My new oven begins...

Ok, first question. I have a 200amp single phase service in my shop, so I wold like to run no more than 2 50amp circuits for the oven if possible. From what I can tell from my searching I can run 8 2500w 240v elements like http://www.buy.com/prod/CH776_456091.../90142979.html and be pulling around 90.1 amps @ 220v (have not checked exact voltage yet). I am also thinking that I can run two 50 amp contactors like http://www.famousparts.com/c25bnf240aco.html. Does this sound right? Also, will this be enough power to heat my 8x8x4 oven? I want to go ahead and decide on my elements so that I can order them and have them in-hand for the frame fabbing process.

[mikekozura]

Re: My new oven begins...

As far the elements and contactors go thats perfect.

It's sounds like enough heat to me but I don't know the formula for that. I'm sure someone will let you know that.

[chromeitout]

Re: My new oven begins...

Anyone know if this would be enough to heat it?

[FSTFBDY]

Re: My new oven begins...

http://www.heatershop.com/btu_calculator.htm

Says you need 13125 watts

[chromeitout]

Re: My new oven begins...

Thanks for the link, this is a good base for figuring, but I'm uncertain on this calculator because it doesn't give heat-up times or max temperatures. LOL formulas are good in most cases but I guess I am looking more for the "well I have an oven close to that size and I have...". We all know that experience is better than schooling sometimes (at least I do with a completely useless 2 year degree ).

[pickleboy]

Re: My new oven begins...

looking at the calculator and given the size of your oven and guessing on average insulation, i inserted 400 degrees rise in temp (this is over ambient), if the oven is 8 long x 8 wide x 4 high it will take 22500 watts. if it is 4 long x 8 wide x 8 high it increases to 26250watts. i am assuming on the insulation if it is good and tight and heavy insulated it will drop these #'s by almost half. this is just to get the rise needed. as for speed it should take around 25 minutes with average insulation and proper venting. with good and tight insulating it should drop this to about 15 minutes. my big oven is 3x5x6high and average insulation and glass doors. it takes about 15 minutes to get to 400. hope this helps.

[chromeitout]

Re: My new oven begins...

Thanks Pickleboy. That's what I wanted to hear. So, I feel pretty safe that with good insulation and 20,000 watts I should be fine. I'll be ordering the contactors and elements tomorrow.

Also, you mentioned glass doors. What kind of glass did you use?

[FSTFBDY]

Re: My new oven begins...

I have a 8x8x13 oven with (4) 75,000 BTU heaters.
Im in the middle of building a 6x6tx8deep with a single 100,000 BTU heater now.

The key is get a good seal and good insulation so your efficency is great.

[ctx97]

Re: My new oven begins...

I have a 8x8x13 oven with (4) 75,000 BTU heaters.
Im in the middle of building a 6x6tx8deep with a single 100,000 BTU heater now.

The key is get a good seal and good insulation so your efficency is great.

What type of heaters are you running? Building a 5x5x5 right now, Was planning on running two or three 28,000 btu propane heaters.

[FSTFBDY]

Re: My new oven begins...

Dayton tube heaters. 75,000 BTU each.

in the little one Im usin one 100,000 BTU one. natural gas.
This one here but 100k

http://secure.data-comm.com/RBIS/Detail.bok?no=205914

[ctx97]

Re: My new oven begins...

ouch, a little expensive for me, I'll be trying to use genric mr. heater propane lamps.

[chromeitout]

Re: My new oven begins...

Now, on to sheet metal. After reading several posts about galvanized I believe that venting the fumes outside and doing a long burn-off before curing any parts it should work fine. I checked with a local HVAC place about galvanized 22, 20, and 18 guage galvanized 4 x 8 sheets. The 22 (for the outside) is 27.50/each. The 20 and 18 were both about 44.00/each. I think this is because he keeps 18 in stock, so I'll use 18 for the inside. Do these prices sound about right? I need 7 sheets of 22 and 12 sheets of 18, ($763.73 incl. tax) so if this sounds high please let me know.

[ctx97]

Re: My new oven begins...

Not real sure on the price on the sheet metal, I got luck and got 6 sheets of 4x8 11gauge galvanized for FREE! , I know it's a little thicker then most people go with, but I couldn't pass it up

[chromeitout]

Re: My new oven begins...

Finally found an hour or so to work on the framing today. Hopefully I'll get to squeeze in a little more time this weekend. It is just tack welded together for now. When I put the sheet metal on I'll pop rivet it all. The oven is upside down in these pics, my floor will be alot thinner.

http://s53.photobucket.com/albums/g60/Chromeitout/?action=view&current=DSC00861.jpg

http://s53.photobucket.com/albums/g60/Chromeitout/?action=view&current=DSC00865.jpg

http://s53.photobucket.com/albums/g60/Chromeitout/?action=view&current=DSC00864.jpg