Water Temperature Controlling with Arduino

Hi, i have a couple of questions.
1-)I want to control temperature of water which has a constant volume with 220VAC current and a heating element precisely (error should be betweeen 0.1-0.3 degree celsius). But i can't decided what should i use for controlling AC power. There are many many options like solid state relay, mosfet, triac etc. As far as i understand these options provides on/off control. I want to use PID control too.
Are there any other options for regulating AC power continously (not on/off like regulating current)?

2-)In addition, temperature range will be between room temperature and 45 celsius. So the heating element and 220VAC maybe too powerfull for this project.
Do you have any other suggestions for heating? (Actually i prefer less power and DC current for portability and security)

NOTE: Heating time is important. I have not much knowledge about electronics so please explain simply.
Thank you for your answers.


A very important piece of information you have not provided is the volume.
Do you want to regulate the temperature of a cup of tea or a swimming pool? :wink:

You are right. Volume will be nearly 1 liter.

If you want to hold it within 0.1 C, you will probably need something in the container to circulate the water (or fluid) to keep from creating hot spots or layers. You will also need good insulation on the container for the same reason. As far as calculating how fast you can heat it (assuming water), look up the definition for calorie - it is the amount of energy to raise 1 gram of water 1 degree C then you can convert from calories required for your container size and how many degrees you need to heat it up to the number of watt hours for example (watts is voltage * current assuming a resistive load with no power factor etc). You can then figure from that how many "watt hours" of energy you need for whatever time you decide is appropriate. You talk about portable - you may want to look into the idea of using 12v for example with it configured for dual power - a battery to keep it at temperature, but an external supply to provide the higher power needed to actually heat it up to the desired temperature.

Thank you for your answer. Do you think a SSR and PID control is sufficient for these tolerances? (i will not use a PID temperature controller, i will use PID library in Arduino software)

Hi, i have a couple of questions.

So you asked the same one THREE TIMES in different parts of the forum?


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