Can I run DC current through a toaster oven heat element?

[veloman]

I have this junk toaster oven (door opens type) that I want to use the heating elements for a heater powered by my 25-45 volt 4 amp solar panel. I want to make a direct connection with just a diode, fuse, and on/off, and maybe a small fan to give it some air flow. Will this work? obviously I will not be running anywhere near the rating of the elements (8amps or higher at 120vac). I just want to convert my solar panel power into heat inside the house in the lowest cost (free) manner. Yes I know PV for heat is stupid inefficient, but at the time I am not willing to invest more money into inverters and grid tying to use the PV as electric power.
So for now, in the winter, I can at least get some heat from it.

I know I can just use 100w incadescent light bulbs, but I would need a lot in parallel, as each one might draw only .3a at 40v

Will this work, or short the panel? Or something else bad?

 

[dnmun]

some heater elements have a fusible link and the the DC current can be so high that it burns the fuse open. i bet yours has that too but you can just solder a wire across the fuse and use it anyway.

 

[gogo]

Here's pictures of a 12" 800W air heater I salvaged from a dishwasher. Its got a thermostat and an AC squirrel cage fan. I haven't tested its resistance yet.

 

[doctorGONZO]

A conductor is a conductor is a conductor. If a thing lets AC pass thru it will let DC pass thru.

Will it behave like you want it to? Test it. You have a multimeter?

Resistance is proportional to the current raised to the second power, current squared. Twice the current, 4 x the resistance and its heat. Three times the current, 9 x the resistance and its heat. But...12V DC compared to 110V AC has much less PUSH to force current through.

So you need to start off with a low voltage DC and carefully work your way up to a high enough voltage to get the heat you want without burning up your wiring or fuse or something. It is very possible that enough current to make enough heat in the element will require new bigger supply wires to avoid frying them.

Good project idea! Good luck!


GONZ

 

[veloman]

Cool, thanks.

I'm sure this is probably a stupid question for most people here, but I was cautious.

I hook up my 22 VOC PV panel to one of the elements and voltage drops to 10v. The element is too hot too touch and steams water instantly. My infrared thermometer does not show the heat at all though.

Oh yeah, it's overcast. Just wait till the sun comes out. :lol:

I'm excited that I have built a free heater and have put the PV to use.

So the heating element is just one big resistor, I get it now.