Current Cost gas meter monitoring?

As revealed at the second homecamp, Current Cost have a very nice addition to their array of energy monitoring tricks: basically a little circuit board sporting a microchip (a PIC16F689 if my squiniting is accurate) and a wireless transmitter, so the gas monitoring item on my to do list is looking a little more interesting all of a sudden.

Richard has already hooked up his gas meter to Pachube but for a few reasons I have slightly different plans. Firstly, my gas meter is not the same. Possibly better and worse for this kind of exercise at the same time: it has an RJ11 socket for counting pulses… but it is covered and declares that only approved equipment should be used. Maybe not a huge deal, but it is gas and we did have three van loads of people looking for a gas leek in the meter cupboard recently, so kind of keen to avoid any… mistakes! Though I suspect that an optical solution, leaving the meter untampered, would not be any safer but would be easier to overlook next time the meter is read. Not that it has any reflective spot on the dials as far as I’ve seen so far. (Any recommendations from someone with experience counting pulses on a Schlumberger R5 meter, or similar, would be great.)

Second difference is that I’d like to go wireless, and if possible avoid needing an arduino. The gas meter is pretty much outside the other side of the house to my home server, with no power supply. So a wireless transmitter, like the one attached to the electricity cable, would be great. It just so happens I have one of those as well now- handy!

Thirdly, having a single display with all the meter readings on has to be the smart thing to do. The display I already have, and the one which will pick up signals from that transmitter, is the Current Cost. Perfect if I didn’t want a server running to connect up to Pachube/the internet, and also perfect if it’s already connected.

So all I need to do is:

  • decide how to read pulses on the gas meter (peel off that cover, or come up with some Heath Robinson alternative)
  • count the pulses and produce a pulse for the Current Cost transmitter development kit at the appropriate increments
  • find out how to pair the transmitter as a gas channel, instead of an appliance channel (if that’s possible)
  • use some gas

Update: after a bit more investigating I think I’ll be using the socket on the gas meter; I’m hopeful a repurposed spare cable from one of the many modems TalkTalk sent will do the trick. I was also wondering about simplifying the gas meter monitor to just register when I’m using gas, rather than worry about the rate. Some sort of 555 timer based circuit to keep the Current Cost dev board input 2 on between pulses maybe? The only thing that runs on gas is the boiler, so a simple on/off signal should be good enough to work out what I’m using. Dale’s recent roundup of HomeCamp 2 has some tantalizing hints of gas monitoring as well. (22 May 2009)

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9 thoughts on “Current Cost gas meter monitoring?

  1. If the only thing using the gas is the boiler why don’t you just trigger off the boiler rather than the gas meter? Dollars to Doughnuts it has a constant rate of gas usage so after a month or two of monitoring and a detailed bill you will have that rate.
    Plus the boiler is inside and likely more amenable to a had wire connection, AND you won’t have to deal with the gas company should they object to the direct connection.

    • Disassociating the gas consumption from the actual volume of gas consumption is a level of abstraction too far.

      If you have a modern modulating condensing boiler they will turn down their power by a factor of about 4. My 24kW regularly runs at a little over 6kW.

      If you have an old boiler with a pilot light – that could be consuming 400W just on the pilot.

      That rather blows the constant gas rate aspirations out of the water.

      If it were the case – you could just use the output of your thermostat to tell you when the boiler was fired up.

      Best to make an opto-reflective sensor and read it with an ADC input on an Arduino – that way you will see individual litres of gas go by.

      Ken_B

  2. That was a well timed comment- spotted it just after pealing off the sticker and testing the RJ11 socket! Spare braodband modem cable worked perfectly.

    I’m still going to rely on a constant rate of gas use, but decided wires trailing out of boiler was unlikely to get spousal approval- I’d rather argue with the gas company!!

  3. Pingback: GasCost « Notes from a small field

  4. Pingback: My first CurrentCost development board circuit « Notes from a small field

  5. Hello, very impressed with your progress on the gas usage monitor and I am looking at doing exact same.
    I also have the schlumberger r5 gas meter, my one is dated 1996 & states 1 pulse every cubic ft. My meter appears to have no mirror digits and I thinking instead of using the rj11 socket directly (low current 3v circuit).
    I just wondered if you ever managed to detect any pulses from the rj11 and what pinout was used. My early background was electronics and I still use 555 timer circuits. I am looking at feeding the pulses from the 555 into the CC dev board and then into my Viglen MPC that is currently recording my elect usage.
    cheers,
    jamie.

  6. I did manage to detect pulses from the rj11 socket. To make things really simple, the two wires in an ADSL modem cable matched the gas meter pinout, so I just pinched one off an old TalkTalk modem and chopped the end off.

    All working nicely, although that graph makes me think the battery finally ran out.

    I was thinking of switching to plan B at some point though, to measure the temperature of the pipe from the boiler instead. Would save having to explain the wire if my gas meter is ever read! Let me know how you get on.

    • jt,

      I have written an Arduino sketch to output the data from my opto-reflective gas sensor in the same XML format as the CC128.

      I can then use Dale’s CC GUI to see the live data from the gas pulse counter.

      A little coding and timing the period between pulses allows me to calculate the mean power of the boiler (or gas cooker/oven).

      With a little more work I should be able to create XML output to show the historical power/pulse count data too – but need to wire some EEPROM on to the Arduino.

      Arduinos are cool and easy to work with but they should have some on board E2 or SD for mass storage and a RTC to make them really useful.

      I hope to have this demonstrable at Homecamp 03.

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