I need to use Nichrome wire for heating purposes. My heating temperature could be among 200 Celsius, voltage should be 220V, wattage should be approximately 1000 Watts, and length should be 52 inches for this. How can I identify the nichrome wire gauges, and since I am going to use coiled wire in what diameter should the coil be?
In case that you want to rate your device as 220V/1000W.
The maximum available current is 1000/220=4.54amp. For this applications It is recommended to use a 80% of the maximum current so finally you have 3.63A. In case of coiled wire half the current.
So you need a wire with total resistance R=I^2*R or 60,6 Ω. The final resistance due to temperature increase @200oC it is only 2% so we can ignore here.
For this level of power and voltage an AWG 19 to 23 it is recommended, because thinner wires is more sensitive to breakage or burning out to this powers. On the other hand wires with longer diameter it takes longer time to reach the equilibrium temperature, and needs off course more current.
Looking at the table http://hotwirefoamcutterinfo.com/_NiChromeData_files/1_Amperage.jpg For 205oC temperature and current around 3.63 amp, the AWG 20 it is good choice Now from table http://hotwirefoamcutterinfo.com/_NiChromeData_files/2_Resistance.jpg the total length of the wire should be L=R/r or 60,6Ω/0.6348Ω per foot = 29meters. But your available space is just 130cm. So you have to coil your nichrome wire.
However coiled wires does not emits temperature to the surround well as strait wires. From practice, and for such diameter of wires an around 5mm diameter of coil is recommended. But again you need 6,8 meters (assuming you leave 3 times the wire space between each turn!). So you have to re-coil your coil on a proper cement form. You can calculate using simple geometry.
Since you can not control the environment changes as well as to eliminate the risk because of the assumptions and approximations, it is highly recommended to use thermostat. Another recommendation is to drive your heating element using PWM current. It is easy since your load is ohmic.
If your supply is 220 volts and the power needed is 1000 watts then the current drawn is 4.545 amps. The resistance of the wire is also, by ohms law, 48.4 ohms. This needs to be the resistance when warmed up.
Regards the diameter, this needs to suit your application.
Hopefully, this link will allow you to choose the wire gauge you need.