I'm building a control board for a solar hot water heater that I built. I want to be able to turn on and off a pump depending on the temperature difference between the storage tank and the panel temperature. I also want to be able to open and close valves to drain the panel if it might freeze.
I've been looking for valves that I can control electronically.
I figure I need a relay to control the pump, but I know nothing about hooking these up. The pump most likely will run off of 120V, but I may want to change it to run off of a solar panel, which would be DC.
There are a number of threads on the forum that discuss interfacing with relays. The usual place to look is this schematic:
But you might prefer to look at this one, too:
Go with whichever makes more sense to you. You'll ned to choose a relay with a coil that you can control from the Arduino (5V or maybe 12V) and contacts that can take the voltage and current required by the pump.
For temperature sensing, there are again a number of threads on the forum that discuss various temperature sensors such as thermistors, semiconductor sensors and thermocouples.
I've been looking for valves that I can control electronically.
Washing machines use these. They need 120v AC to activate.
Another possibility is the valves used in auto watering setups for gardens. The ones we have in Australia need 24v AC to work; I suspect this is pretty common worldwide. Try your hardware store.
You will need anachrocomputer's relay circuit to drive either type.
Thanks for the replies. This is a big help. I never thought about using sprinkler system parts. I did a search and found exactly what I was looking for.
One thing I still need that I forgot to mention is an air vent with a motor and an air damper for a ventilation pipe with a motor. I can then open and close these as needed to heat the house.
