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Xbee, RaspberryPi, line voltage electric heaters
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Xbee, RaspberryPi, line voltage electric heaters

by petek157 on Tue Sep 23, 2014 10:20 pm

Hello Everyone,

I've read a number of posts on thermostats and gathered a bit of info from them. There are just a couple questions.

I have a home with electric baseboard heaters. Each room has it's own line voltage thermostat. I would like to replace the main living room thermostat with a "controller" thermostat, thinking a pi, that would be connected to the other rooms via xbee that has a temp sensor. The main controller would receive temp data from the remote rooms and both log it and decide if the heat needs to be turned on. If so I want the controller to send that command to that room and have the xbee turn the heater on.

So, the questions (I know just enough about all of this stuff to be dangerous):

1.) Is it feasible to use the power that is in the box (typical 220 for inline 2 line thermo) to power the remotes and controller via a transformer of some sort?

2.) Using a relay to turn the heaters on and off. I've been doing a little research on these and can't really wrap my head around all the different ones in the different styles, could someone start me in the right direction for a relay that an xbee and pi can operate for this type of project?

Assuming that #1 is even a viable option I would love some input on this project. Questions, comments or suggestion, fire away.

Thanks in advance

petek157
 
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Re: Xbee, RaspberryPi, line voltage electric heaters

by franklin97355 on Tue Sep 23, 2014 11:56 pm

(I know just enough about all of this stuff to be dangerous)
You are planning to work with lethal voltages so I would recommend a licensed electrician actually do the work. If you have the correct transformer powering the xbee from that is not a problem. For relays I'd suggest SSR's http://www.opto22.com/lp/ssr.aspx?cd=SolidStateRelays&ag=SSR&ad=guaranteed&gclid=CJ-JwJX6-MACFRSEfgodzjAAXQ like these (but you can get them from other sources too.

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Re: Xbee, RaspberryPi, line voltage electric heaters

by petek157 on Thu Sep 25, 2014 5:21 pm

Thank you for your reply. Actually the line voltage I know the most about (I was an apprentice electrician for a couple years) its the electronics part that Im just starting to work with.

One thing that I was thinking of was the flow of electricity and its effect on the transformer/xbee etc. With 220 heaters, Im guessing you know, that the 110 of one line uses the opposite phase 110 line for return and visversa. Would that cause any problems more or less plugging the transformer into that cycle?

Here is a crude drawing of what I am thinking. Again, now having a quick drawing, does this look feasible?

Thanks again
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Re: Xbee, RaspberryPi, line voltage electric heaters

by franklin97355 on Thu Sep 25, 2014 5:30 pm

If you have enough filtering on the transformer that should work. I don't know anything about the existing thermostats but it might be easier to interface with them than eliminate them all together.

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Re: Xbee, RaspberryPi, line voltage electric heaters

by petek157 on Thu Sep 25, 2014 10:16 pm

The old thermostats are just old mechanical spring coil contacts. No way to connect to them that I know of. I've been reading up on supplying power. I will add filtering to my research as well, not familiar with that either. Thanks for your input. If any other little trinkets of info come to mind feel free to share.

petek157
 
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Re: Xbee, RaspberryPi, line voltage electric heaters

by petek157 on Sat Dec 19, 2015 4:29 pm

I finally have freed so time to start looking at this project again. Truthfully haven't done much work with it since the last post. Have been dissecting some other store bought line voltage thermostats and have unfortunately picked up a new question rather than getting any answers. The chips and controls of these store bought inline thermostats only connect to the two 110 power lines no neutral or ground. What type of circuitry is needed for this in order not to be putting 220 volts into the control side of the thermostat?

I envision it like check valve of some sort. It allows the 110 from say the left to flow through to the right using the the other line as a neutral, but doesn't let the opposite phase 110 on the right flow to the left. I maybe completely of base here, but if not, how is this accomplished?

Thanks for any input,
Peter

petek157
 
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Re: Xbee, RaspberryPi, line voltage electric heaters

by franklin97355 on Sat Dec 19, 2015 11:05 pm

I'm not going to make any recommendations for the HV side of the circuit. I don't think you should be working on that without an electrician involved.

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Re: Xbee, RaspberryPi, line voltage electric heaters

by petek157 on Mon Dec 21, 2015 1:11 pm

Sooo.... you posted to tell me that you weren't going to help? I appreciate your concern on the high voltage. I am very comfortable working with electricity in particular 110 & 220. Im not an electrician however I have been wiring homes and working with electricity since I was about 12 years old (my dad owns a construction company and my grandpa owned it before him). If anyone IS interested in helping, I won't hold anyone responsible if I get bit.

Thanks again for your concern (seriously),
Peter

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Re: Xbee, RaspberryPi, line voltage electric heaters

by cdkeith on Fri Sep 23, 2016 8:44 am

hello Pete, I am also new to the micro controller world and it the very same project your asking about that has gotten me interested in it. making a central smart thermostat to control my base board heaters. So far I have not quite figured out what to do but i was planning on using a double relay set up so the controller will shut the first relay on the xbee and use 110v through that to shut a second relay that can handle 220v to operate the heaters. that much i have figured out but I just cant figure out how to run multiple temp. sensors, and outputs, mainly because when it comes to coding i'm illiterate i guess.

Hope this helps, and if you have already figured it out please tell me how so i can follow your lead.
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Re: Xbee, RaspberryPi, line voltage electric heaters

by petek157 on Fri Sep 23, 2016 12:08 pm

Hey,

Truthfully I havent had a ton of time to tinker with this project that much. How ever it is still sitting right there on top of my project desk.

Looking at your diagram, I would say the way that you have it drawn, the AC/AC (High Voltage Controlled) relay is unnecessary. Technically speaking you only need to break one of the 110 legs to turn off the heater. Which looking at your diagram is all your doing anyways. Ive purchased a Opto DC/AC low voltage relay that is rated for 240v. I have my thermo controlling that open and closed which turns the heater on and off by controlling that one leg.

That all being said, remember that when you only break one leg that you still have 110 getting to the heater. So if you ground out to it your going to get bit.

As for the brains of the system, tough to help with out knowing too much about what your attempting. My plan was to have Xbee's with temp sensors in each location that I wanted to track. Those would report to the main controller which is where it would decide what needs to be done (heat on heat off Danial Son). Im not 100% sure what you are doing with multiple outputs? Trying to control more than one heating circuit from one thermo?

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Please be positive and constructive with your questions and comments.