ROT for oven wattage?

[Guest]

Hello.

Is there a rule of thumb for wattage (per cubic foot of oven space) for reasonable pre-heat and efficiency?

I'm considering building an oven just big enough to handle a motorcycle frame and I already have a ton of oven parts/high temp wire/etc.

Basically all I'm lacking is a PID/SSR and high-temp circulation fan. (I have access to nearly free galvanized sheet and other construction materials) But I want to make sure my elements will be up to the task.

-Deek

[tedsfab]

Re: ROT for oven wattage?

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


thats one will give you a good guideline . whats kind of heaters do you have ?

[FirstYearDeek]

Re: ROT for oven wattage?

Thanks for that link!

The elements are from a standard household oven... one is 1500 watts the other is 2000.

That calculator spit out 3,529 watts for 450 degrees so I should be right on the money!

The oven will only be 2' by 3' by 5'6" tall... small by most standards, I'm sure.

I'm not really interested in doing anything bigger; in fact, I'm planning on building it in such a way as to be able to insert a false top half way down and only use the bottom half for when I'm doing smaller bits.

The last thing I want to do is compete with the professional shops in town. I'm a hobby builder/coater so this is out of necessity, mainly!

-Deek

[edit] you know I was thinking; would a space heater fan be heat-resistant enough to work in an oven? Those elements get 700+ degrees...[/edit]

[Guest]

Re: ROT for oven wattage?

I have been checking out convection oven fans as a solution, but haven't found anything cheep yet. i may try and find a cheep/free convection oven on craigs list or something.

[FirstYearDeek]

Re: ROT for oven wattage?

There's a thought... The donor oven was conventional, but that doesn't mean I can't scavenge elsewhere... if I come up with anything, I'll let you know.

-Deek

[Guest]

Re: ROT for oven wattage?

My personal opinion is that the heater shop calculator is much more accurate if you use average insulation rather than good insulation. There is also a better(imo) excel based calculator that is posted on the caswell oven building site.

Your oven at 33 cu ft will be 22% larger than mine(27cf) and I use 5200 watts.

[FirstYearDeek]

Re: ROT for oven wattage?

My personal opinion is that the heater shop calculator is much more accurate if you use average insulation rather than good insulation. There is also a better(imo) excel based calculator that is posted on the caswell oven building site.

Your oven at 33 cu ft will be 22% larger than mine(27cf) and I use 5200 watts.

Hmm.... So maybe a couple of new elements are in order!

Oh well, those are the least expensive parts; I guess it's better to go overboard than sit around waiting for the oven to come up to temperature after opening the door!

-Deek

[Guest]

Re: ROT for oven wattage?

I have a 3x3x6 ft and have 8500 watts (3 elements) and it heats up pretty good. Would like to have about 10,000 but I can live with this, I guess. All the elements came from old ovens.