Water meter

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ame
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Joined: Wed Aug 30, 2006 12:49 pm
Location: New Zealand

Water meter

Post by ame »

Hello,

Just to inspire people with my infectious enthusiasm I wanted to say I am nearly done with a water meter logger.

I happened to be talking to a chap in the Water department of the local Council. I had recently had my water meter replaced and I asked if it had any instrument capability (since it was new, and this is the new thing). He said no, which was disappointing as I had looked carefully at the new meter to see if it had a reflective dot, or other means to retrofit my own sensor, but I couldn't find one. Obviously the man from the Water Dept. didn't think I was too weird as he called me later and said "There is a switch that can be fitted to the meter. If I get you one can we see your data?". Well, what was I to do?

The meter I have is a Kent V100 (made by Elster in the UK). Inside the meter is a magnet that makes one rotation per litre of water used. The sensor is fitted by removing a rubber plug and inserting a plastic moulded module containing a reed switch. The switch gives two pulses per revolution (one pulse for each pole of the magnet).

I have made a small circuit based on the Dallas DS2423 counter chip with battery backup and built it on a piece of Veroboard (stripboard). You can solder SMD chips to stripboard if you cut the tracks in half lengthways, but it's a bit fiddly. The board is in a waterproof box in the garden. 5m of cable connects the DS2423 to the meter switch. 20m of Cat 5e cable connects the DS2423 to the comms room in the house, where it will be connected to the one-wire bus that reads the indoor and outdoor temperatures. Only one of the four pairs is used for this.

So far I have installed the switch, and buried the switch cable and data cable in the garden. I still have to run the data cable under the house, but I did hook it up through the window for testing purposes and I can read it fine (and the sensor works!).

The next step is to run the wire under the house and into the comms room (which is actually the hot water cupboard) then write the software to poll the sensor and store the data.

This is an exciting project, and is progressing much better than my electric meter sensor (mainly because I didn't have to design and build the sensor itself).

I will put an update here when the project is done, but for now I hope that this is enough to inspire people to start/finish any similar projects. Perhaps your local Council, if you speak to the right person, can help you like they helped me?

Best wishes,

A
ame
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Posts: 10
Joined: Wed Aug 30, 2006 12:49 pm
Location: New Zealand

Water meter

Post by ame »

Hi,

Just a quick update. I pulled the wire under the house (yuk!) and reconnected my internal and external temperature sensors. I was able to attach the external temperature sensor to the box with the DS2423 counter in it, so the wiring is tidier now (the external sensor used to go into the house through a window frame).

I have configured Brian Lane's Digitemp software and cron to poll the temperature sensors every 5 minutes, and the water meter every minute. I am now logging the water meter counter reading to a file (1 count = 0.5 litre). The next step is to log only when the counter changes, otherwise the log will fill with identical readings every minute when nothing is happening. Then I'll log to a database and produce nice chartsengrafs.

Did you know that a load of washing consumes 50 litres? Our washing machine manual says 54 litres, and the measurement was 50.

Happy non-denominational festival greetings,

A
ame
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Joined: Wed Aug 30, 2006 12:49 pm
Location: New Zealand

Water meter

Post by ame »

So, it's pretty much done. I have written a quick Python script that calls digitemp to sample all sensors. I use cron to execute this script every minute. In the Python script, if the time is a multiple of 5 minutes I log the temperature data to a file (otherwise I discard it). I then convert the counter reading from the DS2423 to an actual meter reading then if it differs from the previous reading I log the reading to a file. The meter itself has an 8 digit counter, four are cubic meters (coloured white), and the other four are decimals (coloured red), so the meter has a resolution of 1/10th litre (the last digit on the dial), but my counter only counts 0.5 litres so my log contains meter readings ending in 5 and 0. I had some problems with switch bounce on the DS2423. My circuit is based on this one from Maxim:

http://www.maxim-ic.com/appnotes.cfm/an_pk/677

The differences are that I did not include a DS2407, and I connected the water meter reed switch to input A and did not connect A and B together. B has its own 1M resistor to ground, but nothing connected to it. I suspect that the power supply cap (0.01uF) is not big enough, so I added a 0.1uF in parallel and that seems to have fixed the contact bounce problem. I will watch my readings and compare them regularly with the actual meter readings to make sure I am not getting extra counts.

Just a couple more notes- the switch cable is about 5m long and is buried underground. The moulded part that fits into the meter also has a 100 ohm resistor in series with the switch. The wire back to the house is about 20m of cat 5e ethernet cable, of which only one pair is in use. None of the cables are in conduit- they are buried directly in the ground about 20cm below the top surface.

A
ame
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Water meter

Post by ame »

I still have problems with contact bounce. My counter was increasing faster than the meter itself. I have moved the waterproof box containing the DS2423 circuit closer to the meter and shortened the meter switch cable by about 3m. I am suspecting that the long switch cable was also a contributing factor (increasing the parasitic power capacitor on the DS2423 did make an improvement).

Oh, and in case you were wondering, it's summer here in New Zealand, which is why I can bury wires in the garden and crawl under the house. Wouldn't want to do that in winter!

A
Bwired
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Water meter

Post by Bwired »

Hi Ame.
Thanks for the project report! I have my water counter almost running the same. I also use always extra shielded cable for the sensors and as short as possible connected to the 1-wire counter.
When can we expect your water meter online?
Regards Pieter
ame
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Joined: Wed Aug 30, 2006 12:49 pm
Location: New Zealand

Water meter

Post by ame »

Hi,

Thanks for your comments. I was wondering if anyone was actually reading this. I know it is Christmas in Europe, so everyone is visiting or away on vacation. I am on vacation, but I am playing with wires and sensors!

I will know in a couple of days if I am still getting contact bounce. I may be able to shorten the switch cable by another metre, but the cable is not shielded and is moulded on to the switch so I can't replace it.

I am not ready to put the results on-line yet, although I do plan to. This project has motivated me to have another go at my electric meter sensor too.

Best wishes,

A
Bwired
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Water meter

Post by Bwired »

Look at the header of the topic then you can see how many people have red it!
I'm planning to make a topic or something where I put all people who have there home automation, Domotica online. So it's easy for us all to check and see once in a while and learn from each other.
Regards and keep us posted!
Pieter
Macca
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Water meter

Post by Macca »

Gidday Andrew,

I am also from New Zealand and have a 1-wire weather station (http://home.clear.net.nz/pages/andrew.c ... e/SVWX.htm) and home automation network already installed at my house in Upper Hutt. I am keen to discuss your two sensor projects further, so hopefully you read this or the offline email I have snet you and we can discuss them further!

Best regards
Andrew M

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by ame</i>
<br />Hello,

Just to inspire people with my infectious enthusiasm I wanted to say I am nearly done with a water meter logger.

I happened to be talking to a chap in the Water department of the local Council. I had recently had my water meter replaced and I asked if it had any instrument capability (since it was new, and this is the new thing). He said no, which was disappointing as I had looked carefully at the new meter to see if it had a reflective dot, or other means to retrofit my own sensor, but I couldn't find one. Obviously the man from the Water Dept. didn't think I was too weird as he called me later and said "There is a switch that can be fitted to the meter. If I get you one can we see your data?". Well, what was I to do?

The meter I have is a Kent V100 (made by Elster in the UK). Inside the meter is a magnet that makes one rotation per litre of water used. The sensor is fitted by removing a rubber plug and inserting a plastic moulded module containing a reed switch. The switch gives two pulses per revolution (one pulse for each pole of the magnet).

I have made a small circuit based on the Dallas DS2423 counter chip with battery backup and built it on a piece of Veroboard (stripboard). You can solder SMD chips to stripboard if you cut the tracks in half lengthways, but it's a bit fiddly. The board is in a waterproof box in the garden. 5m of cable connects the DS2423 to the meter switch. 20m of Cat 5e cable connects the DS2423 to the comms room in the house, where it will be connected to the one-wire bus that reads the indoor and outdoor temperatures. Only one of the four pairs is used for this.

So far I have installed the switch, and buried the switch cable and data cable in the garden. I still have to run the data cable under the house, but I did hook it up through the window for testing purposes and I can read it fine (and the sensor works!).

The next step is to run the wire under the house and into the comms room (which is actually the hot water cupboard) then write the software to poll the sensor and store the data.

This is an exciting project, and is progressing much better than my electric meter sensor (mainly because I didn't have to design and build the sensor itself).

I will put an update here when the project is done, but for now I hope that this is enough to inspire people to start/finish any similar projects. Perhaps your local Council, if you speak to the right person, can help you like they helped me?

Best wishes,

A
<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">
michaelumangelum
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Joined: Sat Sep 06, 2008 5:17 pm
Location: Ireland
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Water meter

Post by michaelumangelum »

Hi I also would like to get help to install a water meter in my house.
I try to download your documente to get started. But it was not possible.
Could you please help me and send me any information usefull that you may have.

By the way you still measuring your water intake???

Thank you for your attention.

Regards
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