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Thread: Thermostat to control a plugin electric socket

  1. #1
    Automated Home Jr Member
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    Default Thermostat to control a plugin electric socket

    Does anyone know if it is possible to have a thermostat with either PID or fuzzy logic control to send a RF or wifi signal to an electric plug to switch on a 1KW heater?

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  3. #3
    Automated Home Jr Member
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    Unfortunately it is just on and off control.

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  5. #5
    Automated Home Legend Karam's Avatar
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    Just happened to see this in passing by. In principle we can do it but its not a one device neat solution. Out of interest though, here is how (for insight into what might be involved):

    Ok so in our Cortex software we have PID, Fuzzy logic and other more complex control algorithms which, in a nutshell, will take in measurements from one or more temperature sensors in the area of temperature control. These together with the setpoint profile (24hrs x 7 days in our case) go into the algorithm. The algorithm then spits out a control signal value which is an analogue value e.g 0-100%. All well and fine if you have an analogue heat output device e.g proportional valve. However more often than not you only have on/off devices so in this case our software converts the analogue value to a PWM signal (variable mark to space ratio on/off) which for something like a heating system can be on a duty period of 10 minutes or even longer (becaiuse the slow dynamics will smooth out the on's and off's). The on/off signal can then be connected to the physical device - in our case a wireless route could be via a Byron (HomeEasy) wall socket since we have an RF gateway to such, or it could be to a WiFi based socket who's web API is accessible (via our web API client). The socket would then do the heater switching. The human interface part to all of this such as changing set point, providing remote access, etc, (preferably more automation than user fiddling in our case :-) ) is all taken care of elsewhere in the software.

    To show you what I mean I'm attaching a screen grab of a graph from an actual example (although this used one of our wired switching modules). You might want to note the date on this (2002!).

    One complication is of course how to choose the parameters for such control algorithms. There are ways to automate this and adapt these over changing conditions, but its a subject in its own right ....
    Attached Images Attached Images

  6. #6
    Automated Home Ninja Mavis's Avatar
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    Samsung SmartThings have a multi sensor which has a temperature sensor inbuilt and could be combined with their power outlet. Not sure if they can only be used with the SmartThings Hub or if the technology enables them to be used in conjunction with other things. Can also be used with IFTTT.
    http://www.smartthings.com/uk/

  7. #7
    Automated Home Legend top brake's Avatar
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    Honeywell evohome can do this if you use the HC60NG wireless relay
    I work for Resideo, posts are personal and my own views.

  8. #8
    Automated Home Jr Member
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    HC60NG does not appear as supported evohome device on the official documentation though

  9. #9
    Automated Home Legend top brake's Avatar
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    Quote Originally Posted by Caudera View Post
    HC60NG does not appear as supported evohome device on the official documentation though
    It used to appear and is still supported
    I work for Resideo, posts are personal and my own views.

  10. #10
    Automated Home Jr Member
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    Is this the biggest RF relay available? I'd like to switch on and off a 1.5kW boiler and I'm not sure it can withstand the start-up current

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