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Topic: Feasibility of a temperature controlled power outlet? (Read 2172 times) previous topic - next topic

So I think some backstory is needed to get why and what for I am asking this.

As a person who recently struck out and got his own apartment with an old air conditioner (it's very old, even has analog dials for controls) provided by the landlords who is trying to keep bills down in an usually hot and humid Maine summer I think I've come across a solution and a brilliant learning opportunity.

I've been interested in home automation for awhile now just never had my own place (and still don't) so I haven't attempted something like this before. I visited my local radio shack recently and was reminded of the arduino boards. I began to think about building one to control the A/C.

So, I'm wondering if its possible to have the arduino board control the power to the A/C with out having to modify the plug as it's not mine to change. Another thing I'd need is to control this based on the temperature so it doesn't just run or need human intervention. I also would need this function to have an override switch allowing "off" and "on" instead of "automated".

If this is possible places to go and learn so I can start this would be quite nice or even pointers so I can look myself.

Thanks for any help!

PeterH

That should be easy enough to build using a thermostatic switch of the sort used in fridges and electric ovens, there's no obvious need to involve a microcontroller. If you decide you want a more complex controller, perhaps one that adjusts the temperature set point based on the time of day or day of the week, you can buy digital thermostats designed to control domestic heating/cooling systems for not much more than the cost of an Arduino. If you want to make your own for the fun of it, it would be an interesting project. I suggest you'd probably need one or more temperature sensors (perhaps DS18B20), a powertail switch to handle the mains switching side for you, an RTC, and perhaps a display and some push button switches to configure it - and of course a project box.
I only provide help via the forum - please do not contact me for private consultancy.

A thermostatic switch would involve modifying the outlet in someway, yes? If so I can't do that, not my place to fiddle with such things. If not I'd like to look into that at least.

Back to arduino though, I'd prefer to have it be something that is programmable but the only thing I can change is the outlet it plugs into (as in which one not the actual outlet being modified) so i was looking around at RC outlets that plug into existing ones as a possibility. I'm sure there's more ways to go about that even so any suggestions there would be nice.

As for the parts you mentioned mind linking some of them? Lots of "new" terms used there. I've seen a few before but the majority of my experience is in computer hardware not electrical systems.

PaulS

Quote
A thermostatic switch would involve modifying the outlet in someway, yes? If so I can't do that, not my place to fiddle with such things. If not I'd like to look into that at least.

You could create an extension cord that goes between the outlet (unmodified) and the AC plug (also unmodified) that the Arduino can, using a relay for example, make the necessary connections in, as is done with the powertail device.

It seems my A/C uses a fun type of plug and it makes me doubt this is possible. I took a look and it seems it uses a NEMA 6-15 plug. Is this still a possibility?

rclymer

it is absolutely possible, if the flow of current is stopped along an extension cord by a relay then the unit will shut off. I have built many of these with an SSR relay http://www.amazon.com/gp/product/B004HZN628/ref=oh_details_o03_s00_i00?ie=UTF8&psc=1. Use a temperature sensor to determine the state of the relay. Sounds like a fun project. Here's a series of videos that your project reminds me of. https://www.youtube.com/watch?v=hWt_HESKjo8

I'll admit I'm a little confused as to how that relay would work if I'm unable to modify the actual outlet. Any tips?

PeterH

I'm a little confused how you think any of these options are going to work if you don't have the capability to intercept the power supply somewhere along the way. If you can intercept the power supply then all the options are equally possible.
I only provide help via the forum - please do not contact me for private consultancy.

So am I, that's why I'm asking if it's possible. Regardless thanks for the info so far, it has been more than enough to start looking on my own to see if its possible.

Runaway Pancake

Is it 220 or 120?
Either way,
See attached drawing
"Hello, I must be going..."
"You gotta fight -- for your right -- to party!"
Don't react - Read.
"Who is like unto the beast? who is able to make war with him?"

I'm sure I'm wrong given my lack of electrical knowledge but that seems to be a relay that sits between the wall outlet and the A/C's plug that can be switched based on input to control the flow. Not sure where I'd find one for this type of outlet (it looks like this.)

Also as of yet I am without a voltmeter and am unsure of the voltage this plug has. I do plan on getting the proper equipment before attempting this if it is possible as my paychecks come in.

PeterH


Not sure where I'd find one for this type of outlet (it looks like this.)


I think you're thinking about this wrong.

If the device you want to control is plugged into a power source then you need to get a similar plug and socket to make up something that looks similar to a very short extension lead which has your switch/controller in the middle. What you put in the middle is up to you, and as long as it is something that can be connected to wires, it should be feasible to use.

The the plug and socket are a standard type used for plugging appliances into the mains then you could probably find a powerswitch tail or equivalent that is plug compatible which would take care of the dangerous mains voltage part for you.

Depending how much current your device needs, you could probably find a standard digital thermostat capable of controlling it, in which case all you need to do is make the wiring connections to it and turn it on.
I only provide help via the forum - please do not contact me for private consultancy.

Runaway Pancake


... that seems to be a relay that sits between the wall outlet and the A/C's plug that can be switched based on input to control the flow. Not sure where I'd find one for this type of outlet (it looks like this.)

Yes, you're right.
Suitable plugs and jacks, and cable, can be bought at many hardware stores.
Depending on the current, a contactor may be in order
https://www.appliancezone.com/ShowProduct.aspx?ID=64162&gclid=CIaF2fH8jLgCFUThQgodlQEA-w
Repeated high-current surges through relay contacts could result in a "weld".


Also as of yet I am without a voltmeter and am unsure of the voltage this plug has. I do plan on getting the proper equipment before attempting this if it is possible as my paychecks come in.

It's 220.
Either do get the right equipment or don't proceed.
"Hello, I must be going..."
"You gotta fight -- for your right -- to party!"
Don't react - Read.
"Who is like unto the beast? who is able to make war with him?"

mauried

Need to be careful with air conditioners that you dont turn them on and off frequently as this can damage the compressor.
The thermostat in air conditioners has an inbuilt timer built in that makes sure that the compressor doesnt get turned on and off
at a rate thats too frequent, usually around 3 - 5 minutes.
This time is to allow the gas pressure on the high side of the compressor to slowly equalise with the pressure on the low side so that the compressor
isnt trying to start with a load.

arduinoPi

maybe you could just place a servo on the knobs.

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