Help on project relay on water heater/kettle

Hello everyone

I am going to use my arduino uno digital out pin and attach that to an Solid State Relay SSR-25DA 25A /250V 3-32VDC

And i will use that relay to switch an water kettle on and off. It will be a simple water heater.

I have a few questions.

-Will i need a transistor to make the pins work? Because the pin only gives 40 mA and i do not know if that will be enough. -If i remove the button that you have to press down in a water heater, can a relay replace that function? Or will it only work one time. I would like to know that before i buy a water heater.

Picture of water heater:

code (Doesnt really matter)

void setup()
  pinMode(13, OUTPUT); // LEDs - off = red, on = green
  digitalWrite(13, LOW);


    digitalWrite(13, HIGH);

Apologies if the topic looks messy. It is my first time.


-Will i need a transistor to make the pins work?

No just connect it up to a pin, it is in effect just an LED.

If i remove the button that you have to press down in a water heater, can a relay replace that function?

Yes, but make sure that the button is not also a safety cut out button in case the kettle boils dry.

It is my first time.

No it is not you have a duplicate post please remove it.

What is your project for ? Perhaps a sous-vide ?

You can switch the heating element on and off, but you have to know where is overheating safety is. Perhaps it is inside the heating element, or outside. Keep that overheating safety in the circuit, you don't want to start a fire after all the water is evaporated.

Water heaters must have such an overheating safety. Almost every water heater also turns off when the water is boiling, but that a mostly mechanical.

If your water kettle has a physical button/switch that must be operated to switch it on,and moves itself back to the 'off' position when the kettle reaches boiling point, then you can't simply replace that with a relay. You need to either provide a way to physically move the switch to turn the kettle on, or bypass that switch and provide some other way to detect when the kettle is boiling so that you can control the temperature. Note that there are a few kettles that are controlled electronically with a momentary switch which you could replace with a simple relay, but these tend to be much more expensive that the common simple domestic kettles.

Thanks for all the responds everyone.

Im happy that i do not have to get a transistor. The only problem that will be hard to find a solution for as PeterH says is that i will need to figure out a way to control the button, because it will have a timed off switch on it. Maybe if i use a relay and make an estimation of when the water is boiling, maybe then i could set a timer for when the relay needs to be switched off?

By the way the project is a project for school. and since i don't have a real broad knowledge about elektronics is why i would try my luck here. Does anyone have more experience on the button that will be on off after a delay? Imagine if i wanted to remove that switch and try to get it to work with a timer on the arduino with a relay.

It depends what you’re trying to achieve. Will the kettle actually be boiling? If not, you won’t be using the original thermal switch and can just leave it in the ‘on’ position, but that does raise the question of how you will know when you need the kettle turned on and off.

Alright solid state relay came in today and is working with the arduino. Going to try to open up the water heater this friday so i can get to the start/stop switch and add that to the relay. Will keep you guys posted

Alright we went a little in a different direction, the switch of the water heater is completely mechanic. So we attached the relay to the power cord instead of to the button. We made sure that the button on the water heater is always on. Now for security measures we will be using a temperature sensor and attach that to the arduino.