Heat controller that provide 150F to 250F

Hello everyone, I just started learning how to use Arduino and I'm not very familiar with a lot of electrical components. For this project, I needed to build a Heating Controller.

(1) Using at least 2 Heat bands as heating element. (110V 380W Injected Mould Heating Element Band Heater 35x35mm, on amazon)
(2) Heating from 150F to 250F, (depends on the material). I can use 'If' statement to turn on and off the relay at specific temperature.
(3) Power by Home voltage source (~120V)

My concern is, I don't know if a simple relay circuit will be safe. If not what else do I need to add to my system?

One more thing, What relay should I use in this case? Since it will be turning on and off frequently, do i need solid state relay?

Search and look for relays that handles 110 and the current, almost 4 amps for 380W. Most likely the Arduino will need f ex a MOSFET transistor to handle the current of the relay coil.

My concern is, I don't know if a simple relay circuit will be safe. If not what else do I need to add to my system?

For basic electrical safety, a relay (regular electro-mechanical or solid state) will provide electrical isolation between the Arduino and the AC powered heater.

[u]Industrial-type solid state relays[/u] are super-easy to hook-up (with screw-terminals), easy to mount, and they are available in versions that can be directly-driven by the Arduino's 5V low-current output.

As Railroader says, electro-mechanical relays will require a driver circuit, although you can buy relay boards with built-in drivers.

Do you have a way of measuring the temperature? With these temps you'll probably need a thermocouple. Thermocouples put-out a very-low voltage so they need an amplifier and high-gain amplifiers can be finicky, so I recommend you buy the special amplifier board. (Don't try to build it yourself).

Since it will be turning on and off frequently, do i need solid state relay?

I "like" the solid state relay but "technically" a regular relay is probably fine. They last a long time and they are often used in heating/cooling systems. I had a horn relay fail in a car once (there are lots of relays in cars) and that's the only time I remember seeing a relay failure. Regular relays are more "electrically rugged" than solid state relays... They are mechanical and they do eventually wear out but they can usually withstand occasional over-voltage or over current whereas a solid state relay might fry instantly with an over-voltage/over-current glitch. On the other hand, a solid state relay can "last forever" if not abused.

Also, it's standard practice to add some hysteresis (AKA "swing") in a heating/cooling system. For example, if your heater is set to 100 degrees, it comes-on at 99 degrees and then doesn't shut-off 'till it gets to 101, and then doesn't turn-on again 'till the temp drops back to 99. That prevents the relay from "chattering" or the system from turning on/off several times a minute or several times per second. The heat can't change instantly anyway and it makes a more stable-predictable system so you should include some hysteresis even with a solid state relay. (Of course the amount of "swing" is up to you.)