First project - controlling 110v water pump and 220v fan

Projects General Guidance
1

Here is what I want to do - this is my first arduino project and really my first experience jumping into electronics so while I've read a bunch of books all this stuff that I've read is foggy now that I'm trying to put it into practical use.

Some questions.

For the water pump - mosfet or relay? What I need to happen with this pump is that it shut off when water goes down to a certain temperature so there is a temp sensor in there too reading the water temp coming out of the pump. And I want the pump to turn on when another sensor reads a certain temp.

For the fan - same question. Mosfet or relay? I'm not sure what amperage I'm looking at for the fan yet - less than 20 most likely. The fan I want to be run from just a single temp sensor - on at a certain temp, off at a certain temp.

I'm probably forgetting a bunch of questions that I should be asking so please feel free to ask more questions if I've left out details you need or make suggestions for things that I haven't mentioned here that you think are relevant.

2

AC or DC? Voltage?

3

AC Voltage

4

sardonicus:
my first experience jumping into electronics

Do you have experiencie with electricity? Because working with these voltage levels can harm or kill you If you don't have proper precautions and knowledge.

5

sardonicus:
my first experience jumping into electronics

sardonicus:
For the water pump - mosfet or relay?

sardonicus:
AC Voltage

For someone working with Mains voltage this is the type of question that raises a red flag.

I reckon this is way beyond the scope of arduino and requires some electronics knowledge and research. Don't just go for the word of someone here, understand how it works. Don't get pushed down, we all have to start somewhere, but I believe if you don't know the basics you may get seriously hurt.

Get familiar with small things first and from there start moving until you are familiar enough with power electronics to start working with mains.

6

Provided the fan and pump are commercial devices with a plug on them.

For safety i would suggest using one of those led controlled power outlets and use the arduino to send the ir signal.

This avoids the need to mess with mains electricity of which you seem not to have experience with.

7

Boardburner2 that is an excellent suggestion. Another alternative for 120VAC devices is http://www.powerswitchtail.com/

Another alternative is just using a standard switch and flipping it with a servo. Seems like a hack but it's a far safer hack.

EDIT: Assuming the OP is in the US, both legs of the 240V fan must be switched (70E Arc Flash Gloves | Mike Holt's Forum). This complicates things, you may have a hard time finding a commercial off-the-shelf power device that will switch both legs and that the Arduino can interface with. Another argument for the servo-and-switch method.

8

Im pretty sure that us 240 devices exist, i think aircon uses this voltage and im pretty sure home automation caters for this.

9

Much easier to get a contactor and control the coil!?

10

Yes if you know what you are doing, this guy is a beginner.
Circuit is easy but safe construction needs experience.