Iron v Copper for heating

I want to make a low temperature (<30C), low wattage (<30W) heater for keeping wine warm enough during fermentation in a cool room.

I thought about using common green plastic covered garden wire. Since it's the current through a resistance which generates the heat, would there be any disadvantage to using iron instead of copper? It would be temperature controlled and I can't see any problems but maybe you can.

You are looking for something called "a 30W light bulb".

Thanks. It could work but it's not ideal, being fragile and a fixed shape.
I think wire is convenient because I can make it flat.

Iron wire would be better than copper since it has a higher resistance. But you may still need a fairly long length to achieve a high enough total resistance to get only 30W from the mains voltage. 30W at 220V requires a resistance of 1600Ω.

Peltier junctions are flat and very efficient heaters as they heat from 2 sources, the wattage u put in and the heat pump action. You will need a finned heatsink & a fan to spread the heat around though.
You need a 12-16VDC supply to do it.

If u want to run off mains....use a series of higher wattage ceramic block resistors or wire wound resistors. For a 120V supply, which gives an rms of 120V * .7071 = 84.85 V. Power = VI.
I=P/V =30/84.85 = .354 A
V=IR, so, R= V/I, = 340 Ohms of resistance required.

For best radiant action get a number of 5W resistors....perhaps 11 , 30 - 33 Ohm units, string 'em in series, paint 'em black. Array them in a grid to radiate the heat from the bottom of the space. Job done.

Mosaic said:

If u want to run off mains....use a series of higher wattage ceramic block resistors or wire wound resistors. For a 120V supply, which gives an rms of 120V * .7071 = 84.85 V. Power = VI.
I=P/V =30/84.85 = .354 A
V=IR, so, R= V/I, = 340 Ohms of resistance required.

Click to expand...

Mains voltage is given in RMS volts not peak, thus you do not need the .7071 conversion. For 30W the desired resistance is V²/30 = 480Ω.

Corrected....

Get a reptile warmer from your pet store. Flat heat in many low wattages. Andy

Thanks all.
I wrote a better response but it was removed by the software.

[edit]
So it does let me post now but it lost my careful reply.

My mains here is 240V so V squared/R
gives R around 2 k Ohms.

I won't risk losing another a long answer.

Take a look here: Flexible Heaters flexible heaters. Remember, you can operate them with a Variac.

Thanks, but I'm not looking for purchasing recommendations on ready-made items, I was asking for advice about whether iron was inherently unsuitable for a heating element and no-one has brought up a problem, which is good. Analogy: going to a cookery class and instead of getting help about how to cook a meal, being advised to order a pizza.

I'll go ahead and experiment with the iron wire and use a microcontroller, temperature sensor, LCD display and solid state relay as I did before with a seed heater.

Thanks all.