I have a home brew vegetable drier that uses the guts from a small ceramic (1000 watt electric) space heater from Walmart and a *Shimaden* digital temperature controller and a big wood box insulated with plain old pink insulation. It's been working in the temp range required here for years, so you might want to look into those as a possible heat source. I'm a big user of controllers like that for other things around the house too, having them on the sauna, hot tub, greenhouse, and wood drying kiln. COTS controllers like that are something to think about if reinventing the wheel isn't the top priority.
http://www.shimaden.co.jp/english/catalogues/index.html Jim Sealy On 7/1/2014 9:41 PM, James Fackert wrote:
well insulated box and you only need a few hundred watts to get to any reasonable temp. no need for many btus.jim fackertOn Jul 1, 2014 10:18 PM, "Nathan Asdourian" <rawliquid@xxxxxxxxx <mailto:rawliquid@xxxxxxxxx>> wrote:Not sure if 100c would work since they are mostly plastic, but I do have a similar sized metal one that is significantly stronger....uses 110v... Has anyone considered propane? My uncle out in Indiana makes his own roasters...typically trailer deals for a quarter hog or more...The last one he made I believe he used the burners from a couple old furnaces...he did manage to max out what the tank was able to put out...had to turn off one of the burners to get the pressure back up. Anyways, just a thought though for all I know the stuff is probably flammable On Jul 1, 2014 6:37 PM, "Lampe, Mattias SLC CT PEK" <mattias.lampe@xxxxxxxxxxx <mailto:mattias.lampe@xxxxxxxxxxx>> wrote: I had not seen that kind of convection cooker before, but it seems like a very good idea to me. 1200W seems to be a typical power value, and if that’s not enough you could just add a second one. I’d assume it would still make sense to put one or two additional fans inside the oven to move a bit more air. Is it safe to assume that 100 degrees (or maybe slightly higher) wouldn’t hurt a cheap (computer-type) fan? Mattias *From:*sugarshot-bounce@xxxxxxxxxxxxx <mailto:sugarshot-bounce@xxxxxxxxxxxxx> [mailto:sugarshot-bounce@xxxxxxxxxxxxx <mailto:sugarshot-bounce@xxxxxxxxxxxxx>] *On Behalf Of *James Fackert *Sent:* Tuesday, July 01, 2014 7:52 PM *To:* sUGAR sHOT TO SPACE LIST *Subject:* [SS2S-Main] Re: temperature controller with arduino g how about using the lid/heating element/heat stirrer fan from one of those convection cookers that looks like a big glass pot? it is all integrated, built to take high temps, has temp control to act as safety temp limit and I think harbor freight has one on sale for $25. just need,circular hole in top of oven box. jim fackert On Jul 1, 2014 7:23 AM, "Redacted sender monsieurboo@xxxxxxx <mailto:monsieurboo@xxxxxxx> for DMARC" <dmarc-noreply@xxxxxxxxxxxxx <mailto:dmarc-noreply@xxxxxxxxxxxxx>> wrote: Hair dryers / heat guns may be underengineered for the expected duty cycle and runtime. I've scratched my head about possible alternatives. A couple suggest themselves as starting points: 1) small resistance-element type room heater. 2) toaster oven elements. I think the latter may have already been mentioned in a previous post. (1) can certainly handle the runtime, and probably the duty cycle too. Could it get the oven hot enough? I suspect it wouldn't be a big problem, but it's a question. Probably best suited to an "outside the oven" type design. (2) is certainly robust enough to handle the oven environment and get it plenty hot, but might result in an oven with difficult "hot spots" -- and putting it outside the oven a la convection oven might make for an awkward build. Is there now some consideration of not recirculating or at least containing the heated air? The "heat budget" probably won't allow for just venting it when the fan is running. Cheers, Mark L. -----Original Message----- From: Lampe, Mattias SLC CT PEK <mattias.lampe@xxxxxxxxxxx <mailto:mattias.lampe@xxxxxxxxxxx>> To: sugarshot <sugarshot@xxxxxxxxxxxxx <mailto:sugarshot@xxxxxxxxxxxxx>> Sent: Mon, Jun 30, 2014 10:16 pm Subject: [SS2S-Main] Re: temperature controller with arduino Hi all, regarding SSRs, I have some spare ones I can send to Vicente, if needed. I don’t have much experience with thermal calculations and designs, but regarding the use of hair dryers/heat guns my idea would have been to NOT put the entire device into the oven – which indeed would cause some issues with the overheat protection and possibly melt some plastic parts of the devices – but to just use it to blow hot air through the chamber.
