Hi,
I'm a total beginner and I want to control a water heater with a Leonardo board.
I want to use an LM35, suitably housed and a relay or two. Where am I most likely
to find a circuit to follow?
Many thanks John.
Welcome,
I would advise to spend a few days going through the examples on the tutorial & reference section to learn the language of Arduino.
There are many examples including relays and temp sensors.
Hi mycrotrol, I would like to add that you should also do some research on optical isolation or similar as you will be needing to switch high voltage along with high amperage. Here in Australia it is not uncommon to have 240v AC at 25 amps supplying the heaters. Another thing is as you design the system, you should look at making it fail-safe. That is, if anything goes wrong anywhere, the main power is left OFF. Hot water heaters are potentially deadly items if not controlled properly. That is also why they have a water relief valve to release pressure (or release under high temp as well) to prevent explosion. I personally have seen a 250L heater level a brick wall as the owner " plugged the leak" on the TPR relief valve. Another thing to keep in mind is if you are planing to wash with or drink this water, you must keep the temp above 65 Celsius to prevent legionares disease among other things.