My propane fired oven build

[Cronox]

Hi there I want to cure powder coating and ceramic that's the reason I ask If the oven makes temperatures over 650f with the 55,000 btu's propane heater.
the other question if the air come out of the heater if strong or not. Thank you very much Big Toy for your Time.

[bigtoy302]

Originally Posted by Cronox

Hi there I want to cure powder coating and ceramic that's the reason I ask If the oven makes temperatures over 650f with the 55,000 btu's propane heater.
the other question if the air come out of the heater if strong or not. Thank you very much Big Toy for your Time.

I see. I think most ceramics cure around 500f. Maybe this weekend I will see how hot I can get the oven. There really is not that much air that comes out the exhaust. Not all of the air from the blower on the heater enters the oven.

[bigtoy302]

So I finally got around to testing the upper temps for the oven. After I got done with a few parts I cranked the pid up to 600F.

400-500...10min
500-500...10min
550-600...10min

So, it went from 75 to 600F in about 45 minutes. out side oven temp on the wall was about 95F.

[CarWiz]

Hot diggity! That's a toasty oven!

How well does it HOLD the temps?

[bigtoy302]

Originally Posted by CarWiz

Hot diggity! That's a toasty oven!

How well does it HOLD the temps?

It has to work pretty hard to keep 600F. Maybe 80% duty cycle. At 400F it only about 25% duty cycle.

[planebuilder]

Bigtoy:
Nice job on the oven!!
I have one of those PID's on my electric oven (5'x5'x7'), works great as far as accuracy, probably overkill but I can also use the same oven with other programed temp curves to mold plexiglass.
Question..I am building a big propane oven (8'x8'x24'), the pid on the electric oven turns the power on and off very rapidly when near or at set point, like on 1 sec. off 1 sec. on 1 sec...... , SSR's can handle that. Does yours turn the gas on and off often? If so have you worried about lifespan of the valve?
Morgan

[ed_denu]

PID's normally have a 'cycle rate' parameter that allows you to control the frequency of the on/off cycling. My pid goes to 199 seconds.

Only issue would be maintaining the set temperature if the cycle rate were set to high.

[planebuilder]

Thanks Ed, I will look for the cycle rate setting, I guess I missed it last time.
Morgan

[bigtoy302]

It does cycle pretty fast. On for a few seconds off for a few seconds. When the oven heat soaks for a wile it does no cycle as much. I am not too worried about wearing out the valve. It is cheap.

[streak07]

Do you have a brand and part number or more specs on the valve? You say its cheap but when I google "gas valve" I get stuff $40-$400 on up. Any other words of wisdom for someone trying to wire one up? Thanks.