Need advice on relay choice

Hey guys. In full disclosure, I've only had myArduino for about a week but boy do I like it. I'm no stranger to microcontrollers though. I've dabbled with the PIC chips over the years and learned a good bit of assembly language in doing so (although I used to do some fun stuff on the old 6510 chip back in the commodore 64 days!).

I'm working on a temperature controller for my reef aquarium. I've got my Uno to read water temperature using a ds18b20 and decide whether it needs to turn on a fan, a heater, or do nothing at all. I've tested it with LEDs as output as well as used the serial port to verify that the logic I'm using is working and all seems in order.

Now I'm ready to actually wire this up to start using it. I'm not sure what to look for in purchasing the relays needed. Both the fan and heater use 110V AC. The heater is 200W but I'm not sure about the fan. I know that I do not want to be able to hear when the relay is activated. I've got some X10 modules I use that make a very loud click when they are activated and I'd like to stay away from that as these could come on and off every 10-20 minutes depending on the season.

I'm guessing I'll need a solid state relay for this job? Does anyone know if they make a relay that has a standard three prong plug that I can just plug the fan or heater into and then hook up the logic and AC power? I'm really at a loss as to what my options are in picking the right/best relay for the job. Can someone offer any suggestions?


Thanks for the info. The powerswitchtail looks pretty cool but it is out of stock. Price was not even listed.

I think that I will go with the SSR . Can you tell me how to determine what I need to buy? I'm guessing that the signal voltage is 5v with the output voltage being 110V? I am concerned about safety as well as with cost.

It does look close to perfect but it will have the audible click I'm trying to avoid.

You might consider the SSR-10DA solid state relay. At 10A current rating it's overkill for your project, but it has screw terminals and is easy to connect. The lower current ones are generally designed for PCB mounting.

Thanks for the suggestion of the SSR-10DA. Will I need to add any circuitry to the DC input to get this to work with the Arduino, or do I just wire the signal pin and ground and it’s ready?