1

I'd like to empathise that I'm a SW developer with no experinnsce with raspi and have almost no experience with HW. Nevertheless I'd like to use raspi for one project:

I'd like to be able to control with it 1800W heating element. Like this one: enter image description here

I'll have a temperature sensor, which would provide me information and by them, I'll be changing the behavior of the heating element. Work with the temperature sensor shouldn't be any problem, since they're made for raspi.

But my question is - is it even possible to connect it to raspi, which would be used as a power source (220V?) and to control the height of the input power (to lower/increase the temperature) at the same time? I guess I'll need to have some component between. Is there "plug'n play" solution, safe to use for an inexperienced user, which would do the work, so I can just connect it to GPIO on one side and to the heating element on the other?

1
2

You'll need a relay. Since 1.8kW at 220V is around 8.2A, you should aim for a relay which can handle at least 220V 10A. Conveniently, this is what typical relay boards have. Note that most relays have separate ratings for AC and DC current and voltage (typically, 250V 10A AC and 100V 10A DC). Since you'll be using alternative current, you should pay attention to AC rating, usually denoted by AC or ~.

And you don't really need a relay to be opto-isolated. Now, I'm not saying mains voltage is not dangerous (keep in mind it can be lethal), or 1.8kW is not a big deal, but if something goes wrong, opto-couplers are unlikely to save you. That said, most relay boards (even cheapest ones) have them, and there's no harm. If you're looking for something plug&play, there's PiFace, but most relay boards will do.

And make sure you respect at least basic safety rules. Make sure your system works before you put 220V on, to avoid any surprises (you can connect a light and a toy battery to simulate your heater and mains power). Buy a case and only switch 220V on when the case is closed and no "hot" wires can be accidentally touched. And make sure you power your project via an extension cord with a switch, so you can power it down instantly if something goes wrong. Don't rely on "pulling the plug": electrical wires can get hot, and operating a plug can prove difficult under stress.

4
  • Oh....I got another idea - wouldn't the safest and maybe the easiest solution be, switching on/off a wireless power plug to which I would plug in the heating element? Nov 16 '16 at 17:06
  • Yep, if you have a wireless power plug which you can make work with your RPi, I'd say go for it. That will let you skip through most of the dangers related with 220V. Relay boards just tend to be cheaper and easier to program, so everyone uses those. Nov 16 '16 at 17:12
  • I don't have, nevertheless they're about the same price as the power switch tail I mentioned in other comments. And I found some tutorials how to control wireless power plugs with your raspi. So I'll probably go this way.. Nov 16 '16 at 17:28
  • I found this...maybe not the cheapest, but probably the most idiot-proof solution possible :) energenie4u.co.uk/catalogue/product/ENER002-2PI-EUR Nov 16 '16 at 17:33
0

No.

The Raspberry Pi is powered at 5 V. Using it as a power source for a heating element with 1.8 kW would require it to cope with a current of about 360 A - about the 110-fold of what is advisable and definitely in the range of the impossible.

The only way to do this would be to have a power source which is being controlled (but not powered) by the Raspberry Pi. However, I would strongly advise to start with something more simple. 1.8 kW is a lot of power - you could easily burn down your house or inflict serious (possibly lethal) damage on people. On top of that, no insurance would cover that..

5
  • That's why I was asking for some safe plug'n'play component I could use. I don't intend to solder my own solution. I'd bet that there has to be something available on the market. I just don't know, what to search for. Nov 16 '16 at 15:51
  • It's not (only) about soldering - it's about controlling high power appliances with self-written code, possibly no fuses and "no experience with HW". I really don't mean to offend you, but even the idea of routing the power through the Pi sounds like you should not start into the world of automatisation and hardware with this project.. Nov 16 '16 at 15:56
  • I get your point. Nevertheless with using something like this it shouldn't be a big deal, huh? sparkfun.com/products/10747? I mean from one sensor I'll keep getting information about temperature and depending on it, the power will be switched on or off.. moreover the heat source will be isolated in a non-flammable heat isolating shield... The only thing I was worried about was handling the high voltage transformation.. Nov 16 '16 at 16:09
  • Yes, something like that would reduce the risk of wiring mistakes (however, you'd need a bigger one - that one is not for 220V) and a non-flammable surrounding should greatly reduce the damage in case of a software malfunction. I just wanted to make sure, that you (and possibly others, who read this) are aware of the risks. Nov 16 '16 at 16:15
  • There is also a kit for 200-240V. powerswitchtail.com/Pages/PowerSwitchTail240vackit.aspx So if I'd ask ask somebody more experienced than me, to assemble it, and connect it all together, it might be a solution. I'm not suicidal to do it all alone :) I'm a software engineer ~~~> I know how to code, but I'm dangerous to myself and everybody close to me, when I decide to try something new... Nov 16 '16 at 16:54

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.