I want to build a thermostat and I'm not sure what power resistor to choose. The thermostat will be build inside a broken microwave oven. The resistors will be connected to 230V AC and they will be controlled by an arduino pro mini for AC PWM using a triac + other components.

I'm thinking to go for 2 or 3, 50W 1.5k ohms power resistors connected in paralel.This is how they look: https://www.tme.eu/en/details/ax50wr-1k5/50w-resistors/te-connectivity/1-1625984-9/

According to my calculations, I will have:

I = 230/1500 = 0.153A

P = I x V = 35.19W

So 35.19W is ok, given that the resistor maximum power is 50w. But in the data sheet is mentioned that without a heatsink the maximum power drops to 20W. So I don't know how the metal plate of the microwave oven would compare to a heatsink. It would be safe to use these resistors?

I want to build a thermostat and I'm not sure what power resistor to choose. The thermostat will be build inside a broken microwave oven. The resistors will be connected to 230V AC and they will be controlled by an arduino pro mini for AC PWM using a triac + other components.

I'm thinking to go for 2 or 3, 50W 1.5k ohms power resistors connected in paralel.This is how they look: https://www.tme.eu/en/details/ax50wr-1k5/50w-resistors/te-connectivity/1-1625984-9/

According to my calculations, I will have:

I = 230/1500 = 0.153A

P = I x V = 35.19W

So 35.19W is ok, given that the resistor maximum power is 50w. But in the data sheet is mentioned that without a heatsink the maximum power drops to 20W. So I don't know how the metal plate of the microwave oven would compare to a heatsink. It would be safe to use these resistors?

I want to make fermented yogurt from bacteria. So I need a temperature between 40-45C so that the bacteria wont die. Also, in the instructions, it says that in order to make ticker yogurt, it would help to keep the milk at 70C for 30 mins. That's why I'm doing it. But in the future, I might use it for other things as well.