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pluggy
Geek


1164 Posts
Posted -  09/05/2009  :  22:32
I've always been fascinated with numbers, especially numbers relating to the real world.  I've mentioned part of this in other threads but I thought I's start a new one. This page is my home server, 

http://pluggy.is-a-geek.com/index.html

I've had it in one form or another for several years.  Initially it was for controllining my daughters internet usage, but having a computer (albeit a small one that doesn't use too much electric) running all the time just for one purpose grated a bit.  So I set to making the box earn its keep.  The graphs are pretty much in the order I implemeted them, the first one is over a year old, although its evolved a bit.  It shows our internet use.  It uses a bit of 'bash' (Linux command line) scripting to extract the amount of traffic running through the server and graphs it against time.  I always wanted to know how much bandwidth we used as an household, now I know.  The second one grew out of it, it shows which of our computers are turned on and gives clues as to who is using the bandwidth.  It scans the network to find which machines are turned on and allocates each one a different number (4, 2 and 1) so the graph shows not just how many are switched on, but which they are.Its Binary in effect, 3 computers gives eight diffent variations of which are turned on, translated in a number from 0 to 7 (all off to all on).  I made the server run a webcam which appears on this page: 

http://www.pluggy.me.uk/webcams.html

This has appeared in numerous threads on here in the past. I also have a security camera inside the house, although this isn't publicly viewable for obvious reasons,  

It was this that caused me to upgrade the eight year old server as it didn't have enough horsepower, the new motherboard 

http://www.dabs.com/products/intel-s775-intel-945gc-ddr2-matx-al-5DD3.html?refs=50520-51510000

also uses quite a lot less electricity as well as being much faster.   Being a new board it does clever things like being able to monitor its own temperatures, which is where the third graph comes in.    This gives me a bit of real world feedback beside the temperatures inside the computer, because they varied with the room temperature and whether I've left the server cupboard door open. I was also interested in electricy usage of appliances and bought a plug in monitor which wou tell you how much electric what you had plugged into was using.  

I wanted to apply this to the whole house, all the time which set me down the microcontroller path.  A microcontroller is a small computer with 'real world' connections that is frequently built into all kinds of gadgets including said electric monitor.  They have been around for a long time but getting hold of a system you could program yourself was often a costly business. I looked at numerous ones at the bottom end of the market (affordable) but they were restrictive and often wouldn't run with anything other than Windows. I eventualy came across the Arduino, which is all open source, including the hardware and is cheap and up to what I wanted to do.  

http://www.arduino.cc/

The one illustrated is the original version with RS232 interface, it needs an interface that often isn't fitted on new computers and a seperate power supply.  The new ones kill two birds with one stone and uses USB both for communicating and powering the board.  The software to control it will run on Windows, Linux and Mac. So I bought one and also bought a current transformer off ebay, which allows the current flowing through a wire to be measured without being physically connected to the circuit.  The first step was the red line on the electricity graph,  using the Arduino as a digital AC voltmeter to measure the current coming into the house.  Which is when I came across the weakness of such devices (at least the 'consumer' devices) and dragged me into the sordid world of apparent power vs real power and power factors.  I couldn't get any real correlation between the current and what the meter was saying I was using.  

This brought me onto the green line on the electric meter,  this one involves a 'reflective object detector' and measures how long it takes for the aluminium disk in the meter to spin (theres a black mark on one position of the disk which is what it tracks) This is convertable with a bit of maths to a direct wattage, I plot them on the same graph and there are often wide discrepancies between the two.

The next step was using the same technology on the Gas  meter.  Its an 'odometer' type meter but the last digit (1000ths of a cubic metre) has a silvered bit in the centre of the '0'.  It just times how long it takes to rotate and works out a figure for wattage. This can only be approximate as there are two unknowns when it comes to calculating your bill (which is in kwh, the same as electric), one is the 'conversion factor' which corrects for the temperature of the gas (cold gas is denser and thus has more energy than warm gas) and the actual energy content of the gas (Mj / m3) which varies on where it comes from and its impurities.  I use some figures I pulled off my last gas bill.  It works in fairly large steps as the meter only revolves fairly slowly and I don't get more than 3 or 4 revs in a minute.  It stops altogether on a frequent basis (unlike the electric meter which thanks to the stuff that runs all the time, never stops.)   It has no way of knowing whats happening between the pickup point on the meter, but it does accurately track gas usage over time.  If say its 15 minutes for a revolution of the meter, it could be say the hot water being turned on for a few seconds and the combi boiler firing for a short time or a gas ring on low for the whole quarter hour. 

The last thing I added was the temperature graphs.  These use thermistors and as yet are un graduated, they just plot the voltage measured from the analogue-digital convertor.  The thermistors and the resistors in the circuit are wide variation and/or unknown specification so I can't derive accurate figures by calculation.   I'm currently reading thermometers against their readings.  

They've given me some ideas for controlling the C/H boiler from the microcontroller, to improve its behaviour and/or running costs. It frequently cycles under certain conditions continually firing and stopping which is both distracting and probably isn't doing the boiler any favours.  It would be straight forward to stop that using the microcontroller, it also opens up possiblites like adjusting the boiler behaviour depending on the outside air temperature(and thus how quickly it cools down when the heating switches off). Watching it this morning, the room temperature continued to rise for 35 minutes after the boiler shut off due to the heat in the radiators, there has to be room to allow for that with a microcontroller.  Laughing  

Another option is to be able to switch the heating on or off remotely using a web browser on a mobile phone for example.  And timing the boiler to come on at different times depending on how cold it is.  It can take several hours to get  a really cold house warmed up, and not very long if its mild. Has to be room for savings in there...........

 

The temperature selection at the bottom of the page doesn't do anything, its a proof of concept - when its live it will be hidden behind a password.  Wink

 

Edited by - pluggy on 01/07/2009 17:29:58


Need computer work ?
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Pluggy's Household Monitor
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Stanley
Local Historian & Old Fart


36804 Posts
Posted - 10/05/2009 : 07:33
Brilliant Steve! I applaud the effort you've put into getting control of the house. One of these days all houses will have something similar to what you are doing so you are well ahead of the curve. When I was running engines and boilers I could never understand why more energy wasn't put into monitoring what was actually going on. Perhaps they thought the firebeaters were too thick to understand the data! Loved the new-to-me concept of cold gas being denser. Of course I knew this but hadn't picked up on it. Why does my mind fly to fitting a refrigeration coil to the incoming pipe?  Alright, the unit would take more power than it saved but even so, it's an advance on the old fashioned ways to fiddle a meter. (Before the Gas Police come, no, I have never done it but being an old fitter I recognise the possiblilities. I used to know a garage on a site in Barlick that had permanent gas heating because I was told they found a redundant gas pipe when excavating for the site. Long gone now and my lips are sealed but it wouldn't surprise me if there weren't other examples of this.)


Stanley Challenger Graham




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frankwilk
Senior Member


3975 Posts
Posted - 10/05/2009 : 08:15
I like it to Stephen, not had time to digest it all just yet but will print it out and study it.
cheers



Frank Wilkinson       Once Navy Always Navy Go to Top of Page
wendyf
Senior Member


1439 Posts
Posted - 10/05/2009 : 09:33
We have a rather complicated heating system for which Colin has built a control system using programmable logic. We have three inputs, the oil fired boiler, woodburner with back boiler and solar panel. The heat goes to 2 hot water tanks (its a long thin house!) and central heating. The controller monitors water temperature in the tanks and operates various valves etc. making sure that heat from the solar panel and wood burner are maximised. Its all beyond me.

Wendy


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Tizer
VIP Member


5150 Posts
Posted - 10/05/2009 : 11:36
Brilliant stuff! If only all plumbers were trained to this same level we might move into the 21st century!

"cold gas being denser" - Stanley, that reminds me that the best time for breaking the land speed record in your racing car is first thing in the morning, when the air is coldest and most dense and you get the maximum mass of oxygen into your engine.


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frankwilk
Senior Member


3975 Posts
Posted - 10/05/2009 : 14:33
For CCGT plants  the temperature for performance tests is always taken back to 15c or 60f  to have a level playing field  for the GTs performance. The colder the air the better performance.



Frank Wilkinson       Once Navy Always Navy Go to Top of Page
Julie in Norfolk
Senior Member


1632 Posts
Posted - 11/05/2009 : 06:42
This has got my thought buds thinking....


Measure with a micrometer.
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Stanley
Local Historian & Old Fart


36804 Posts
Posted - 11/05/2009 : 09:20
It's got the government thinking as well, someone is reading the words of Pluggy. Announcement this morning that all meters are to be changed for smart meters. The spokesman went a bit coy when asked who was going to pay for them...


Stanley Challenger Graham




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WolfSG
Regular Member


89 Posts
Posted - 11/05/2009 : 10:26
In South Australia all new land sub-divisions of lots greater than 20 lots will now have to provide for fibre optic cable to homes. This will enable homes to have high speed internet, cable TV and the like without aerials or satelite dishes.
Coupled with solar HWS, solar volatic?? cells to put electricity back into the grid, smart meters and the ability of Power companies to turn off airconditionersin homes for a short period of time in times of great energy use it looks like the Government is forcing us into the 22nd century!



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pluggy
Geek


1164 Posts
Posted - 11/05/2009 : 13:11
One or two glitches, I'll need to move the outside temperature sensor (or ignore it at certain times of the day) the temperature goes daft when its in the sun.  I suspected when I put it in, but its a lot more work to get it on a north facing wall.  My electric meter sensor has stopped reading overnight. I suspect the phototransistor has come unstuck from the meter glass, I'll have a look when I get home.   My mains switching relays have arrived so I can turn the boiler on and off with the microcontroller. 


Need computer work ?
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Pluggy's Household Monitor Go to Top of Page
Stanley
Local Historian & Old Fart


36804 Posts
Posted - 12/05/2009 : 07:42
The answer is a lovered wooden box Pluggy which is what the Met Office use to combat the same problem with their instruments. There is a name for it..... go find a specification. No point re-inventing the wheel. I seem to remember in the days of oil-fired CH you could opt for automatic delivery based on the oil company's temerature readings. I think they called it the 'degree day' system.


Stanley Challenger Graham




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Stanley
Local Historian & Old Fart


36804 Posts
Posted - 12/05/2009 : 07:45
Found this on Wykepedia...

The degree day system is based on the amount of fuel a customer has consumed between two or more deliveries and the high and low outdoor temperatures during the same period. A degree day is defined as one degree of temperature below 65°F in the average temperature of one day. In other words, to arrive at the number of degree days in one day, the official high and low temperatures for that day must be obtained. The two figures are then averaged, and the number of units this average is below 65°F is the number of degree days for that day. For example, if for Tuesday, November 3, the high temperature is 70°F and the low is 54°F, the average is found by adding 70 and 54, which equals 124, and then dividing by 2. The resultant figure is 62, and by subtracting 62 from 65, it is determined that there were three (3) degree days that day. To determine usage or "K" factor, first compute the number of gallons of fuel oil used in a given period. Then, using the cumulative total of degree days for the same period of time, you can figure the "K" factor, or the number of degree days that one gallon of fuel will last at the current rate of consumption. This factor is arrived at by dividing the number of degree days in any given period by the total number of gallons of fuel consumed during the same period. For example, if during the month of November your furnace burns 200 gallons of fuel oil and assuming that we had 300 degree days, your "K" factor would be 300 divided by 200, which equals 1.5. In other words, each gallon of fuel oil provides you with 11/2 degree days of heat. The next step is to determine how many days' supply remain in the tank once it has been filled. From the total tank capacity, you can subtract a number of reserve gallons which depends, of course, upon the size of the tank. Then multiply the number of gallons of usable fuel by the "K" factor, and you have what is known as the Degree Days of Usable Fuel. Using this figure, oil companies can arrive at the degree day of your next scheduled delivery.

 


Stanley Challenger Graham




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pluggy
Geek


1164 Posts
Posted - 12/05/2009 : 14:43
The delightful thing about where the sensor is is that its invisible and didn't need any work to put it where it is.  I have an old cast iron pipe which brings the mains into the house, it was very easy to slide the sensor on its wire down the pipe from the inside to the outside.  A slatted wooden box is a bit of an overkill for a single thermistor (about 4mm dia and 2 mm thick and cost around 50p ). It would get abused where it is on a public pavement.  The outside air temperature is most use early in the morning and last thing at night.  It only gets sun between about 8AM and noon in summer and hardly at all in winter .  I'll just ignore it at those times. 

The phototransistor had fallen off the meter, I've stuck it back and suspended its hanging wires which probably contributed to its demise. 


Need computer work ?
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Stanley
Local Historian & Old Fart


36804 Posts
Posted - 13/05/2009 : 07:01
Ah, hanging wires!  We recognise that problem!!


Stanley Challenger Graham




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bcopley
Regular Member


69 Posts
Posted - 15/05/2009 : 20:39
Oh how I wish I were a man then I could understand all this stuff.


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Stanley
Local Historian & Old Fart


36804 Posts
Posted - 16/05/2009 : 06:20
BC. That last one was a reference to a computer problem I had which persisted for almost 12 months and in the end was tracked down to a bad connection to a hard disk caused by the weight of the connecting wires displacing the plug. Nothing to do with gender simply areas of knowledge. My daughter Janet is the best software engineer I know but she's useless at fixing PCs. Horses for courses. (and age and experience as well of course)


Stanley Challenger Graham




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