Hi all.
I've been playing with OEM for a few weeks now with an Arduino 2560 and an ethernet shield. Basically, I modified the "CT only" sketch to add code to send data through ethernet to my PC with emoncms on it. Great.
I'd like to take that one step further and try the whole thing real life in my house. The heating is mainly gas, so I'm interested in gas metering. An external temperature would be nice. And of course electricity. (This is mostly for the fun of it, so I don't mind having only one emonTX in a first step and not being able to monitor gas and electricity at the same time.)
Electricity
Concerning the electricity, my meter looks like this :
Everything is sealed, even the wooden frame. I don't see where I could fit the CT. I also wonder how anyone would operate on the electrical circuits without having to break into the drywall (plasterboard). It is a house we rent, by the way.
I have the feeling I'm screwed. Is this correct ?
Gas
The gas meter is an actaris g4 gallus 2000 (specs, installation guide) :
The spec says :
The meters are available with metric or cubic inch indexes. They come with a permanent magnet for pulse generation and can be retrofitted with a pulse transmitter.
Is this magnet of the kind that is referred to in the Gas meter monitoring page ? Do you thing I could try to implement such a feature ? I think some other people on the forum are interested as well.
Thank you for your feedback.
Re: Are my electricity and gas meters OEMable ?
The spec of the gas meter also says "Standard 0.01 m3 / pulse".
With a calorific power of about 10 kWh/m3, this would mean 0.1 kWh / pulse.
When using our gas stove at a power of 2 kW, we would then get a pulse every 3 minutes, which means the cooking could be differentiated from the heating on the measurements.
Re: Are my electricity and gas meters OEMable ?
"It is a house we rent, by the way. ... I have the feeling I'm screwed. Is this correct ?"
Depending on your relationship with your landlord, you could indeed be correct!
There is some hope for the electricity meter - shine a light (visible or infra-red) at the meter and watch the black segment on the disc go past. You know how much energy this represents (It should be written on the meter face - I can't see it for glare from the flash) so count pulses to give total energy and the time between them to give you rate (power).
I can't answer for the gas meter but it certainly seems worth a try.
Re: Are my electricity and gas meters OEMable ?
As Robert says above you may be able to count the numbers with a pulse count for electricity but a simple question to your landlord may allow you to get into the back of that board to fit a clamp. It would only be one small cable coming round from the back so no real mess or damage (which is probably what the landlord would care about).
the gas looks fairly simple as it has a magnetic pulse so you can capture that with the pulse input on the emontx and a Hall effect.
for temperature you can use the one wire system on the emontx but also have a look at Nathan's site http://nathan.chantrell.net/tinytx-wireless-sensor/ for some great little wireless sensors to monitor temp. Especially as you won't need to run any cables between them (landlord/wife friendly).
good luck.
Re: Are my electricity and gas meters OEMable ?
You're right, Robert, I forgot to mention that. There is that black triangle on the disc that could be used to count pulses.
Has this ever been done on OEM already ?
It's not obvious to me what kind of sensor would be used to "watch" the black segment. Assuming it delivers the same kind of output than the "light to voltage" sensors used for flashing LED's, perhaps could it be retrofitted on the pulse count port of the emonTX ?
Re: Are my electricity and gas meters OEMable ?
You would certainly use the pulse input. I have not done this, but it has been done (there are commercial units that use this principle). I think you will need either a light-dependent resistor (as used in the emonGLCD) or a photo-transistor or photo-diode. You will probably need a lens to focus the image so that you only look at a small area of the disk, then of course you need a LED (narrow-angle or again with a lens) to focus the light onto the spot you are looking at. I think a web search will throw up some information. (Sorry, I don't have time to research this for you).
Re: Are my electricity and gas meters OEMable ?
Robert : "(Sorry, I don't have time to research this for you)."
Unless you're really interested, don't.
I can test the electricity monitoring elsewhere.
Regarding my house, a gas metering would be more interesting anyway.
@Tailzer :
It is not only the landlord I'm concerned about. The wooden board itself is sealed (by the power provider), which means it is forbidden to unscrew the screws and have access behind it (which I find weird as one would certainly need to operate somewhere behind that board when doing electricity works).
Thanks for confirming the gas meter can be monitored. Perhaps can I can try to join the efforts adding such a feature to OEM. I remember reading messages on this board from people doing the same thing. The gas meter box is outside, accessible from the pavement. Not the ideal place for debugging... But I could fit in an emonTX with both pulse counting and temp sensor, to have the external temperature as well.
Re: Are my electricity and gas meters OEMable ?
Hello,
I also have the actaris g4 gallus 2000 Gas meter ;)
Did you find a reliable way of counting the pulses on this model?
Re: Are my electricity and gas meters OEMable ?
Hi.
Sorry, I didn't see your message.
As you can see on my profile, I have tested a few sensors, one of which seems to detect the wheel turn reliably.
There are still open questions regarding the processing, but maybe the answers are obvious and I just need to get myself around it a little more.