Electricity costs

After replacing nearly all light in the house with CFL's and replacing the old fridge with a class A one I was expecting to see a difference in the monthly cost of leccy, but no!!
I have used 1344 units in 76 days according to the latest bill, so a whopping 17.6kw a day !! now this seems a lot to me, house is heated by oil, cooking by electric, three meals a day cooked, one was through the washing machine and one tumble dry a day.
any one else done any studies on similar ?
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Staffbull wrote:

18kW hours per day means you have an average consumption of 18/24 750W. If you have a couple of PCs left on 24 hours a day, that will easily account for 200-300W. Add to that the fridge and a few lights, and you can easily have a background consumption of say 400W. The rest will come from your washing machine, dish washer, cooker and (especially) tumble drier. Quite believable.
--
Grunff

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Couple of laptops on for 10 - 12 hours a day so you werent far off the mark, but after about 11pm there's nothing on apart from the fridge and freezer till 7am so there should be a BIG dip in demand there, I still feel sommats not right ! complete long shot but have meters been known to be out of calibration to an extent ? I,ve ordered a plug in power meter to see whats drawing what, My mother and father live up the road similar house and she has the cooker on most of the day, with a monthly bill of £34 !! same company (scottish power)
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Pick a couple of days, and take hourly meter readings, just to see if you have a high background load, or if there's a large load which comes on at a certain time. This might help narrow down what's causing it. You could also try switching everything off (not at the main switch, but at each appliance), and see if the load drops to zero, or if there's something switched on which you don't know about (e.g. the immersion heater).
I have a 2kW convector heater which is switched via X10. At the end of the summer, I noticed it was on. I checked back through my computer logs and saw the last X10 command I sent it was an OFF, way back in February. Fortunately it was on a thermostat, but even so, it had been coming on, probably during the night, and eaten about £50 in electricity, comparing back with previous years. I guess the X10 switch picked up a bit of noise with caused it to come on (I've had this happen with X10 control of lighting during a power surge/dip). I have since changed the computer programming to send a gratuitous X10 ON or OFF command to it once a day to reinforce its intended state.
In another case, about 2 weeks after I moved in to a house, I happened to notice the immersion heater was switched on in the airing cupboard since the pervious people had moved out. Since I was heating the cylinder with the boiler, this wasn't needed. It didn't seem to burn up a noticable amount of energy though.
--
Andrew Gabriel

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On 03 Feb 2007 14:11:16 GMT, snipped-for-privacy@cucumber.demon.co.uk (Andrew Gabriel) wrote:

Can you provide a bit more info on your "X10 set-up" - sounds interesting?
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I have a Comfort alarm system, which includes Home Automation capability. I don't use much X10 as mostly it is all hardwired. I use X10 just for the ability to control portable appliances, and where I want HA control of dimmable lighting. The HA programming is split between the alarm system (for the parts which can usefully run on battery during a power cut) and a PC (for the parts which are useless without a mains supply, such as the heating).
The alarm system provides all the inputs and outputs for both alarm and HA functions (currently got 40 inputs and 40 outputs installed; nearly all the inputs are used, but lots of spare outputs). The alarm also sends and receives X10 commands. The PC is connected to the alarm, and via that, picks up all inputs, outputs, and X10 data received/transmitted. The PC interfaces to the room thermostats through a combination of a 1-wire bus around the house supporting several DS18S20 digital thermometers, and D/A inputs to read the position of the temperature set dials on the room stats (which are actually potentiometers). Software in the PC decides what temperature each heating zone should be (e.g. use temperature setting on room dial, or a preprogrammed temperature for unoccupied house, night time, or frost protection as appropriate). The PC also provides for remote access and off-site logging. I usually switch my heating on as I leave the office.
My boiler is a Keston C25. This has an electrical input to call for heat, and two outputs, burner on, and lockout. These are all connected to the alarm, and via that, to the PC. If the boiler does lockout, the PC will switch over to use the 2kW convector heater instead, which it does by telling the alarm to send the appropriate X10 command to the heater switch, which I was referring to in the article you followed up. When I originally installed the Keston 5 years ago, I was working for Sun Microsystems and spent periods working in the US. I was concerned that it might lockout and the house freeze in my absence. Actually, it never did lockout until a few months ago (due to drooping ignition electrode, a common failure in Kestons it seems). The alarm phoned me to tell me the boiler was locked out, which the lockout input on the alarm had been programmed to do. As it happened, I was at home at the time, but if I was out, it would have been useful to know this had happened. Looking back through the system logs, I could see that for a week before it locked-out, it had been having trouble lighting, often lighting and immediately going out, before staying alight on the second or third attempt. I could program the alarm to alert me if it starts doing this again, to forewarn of impending failure.
--
Andrew Gabriel
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Essentially no laptops will ever use 100W. 60W is about the most, when charging, or 30W when in use. Mine uses around 10W, but isn't very large.

Yes.
The plug in power meters of the electronic sort can be significantly out on modern power supplies of over 30W or so. As in 100% out.
This may or may not be the case whith the one you have - the three I bought from seperate vendors all suffered this. The reason is that they are built to a price, and were designed without regard to 'power factor correction' - which now has to be built into power supplies of over 30W in the EU.
Turn off _all_ loads you know about. Now, see if the meter still turns.
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Ian Stirling wrote:

Some of these "kill-a-watt" type meters claim to *measure* power PF, is this type still affected by PFC equipment? Any comments on the accuracy of e.g. http://www.maplin.co.uk/module.aspx?ModuleNo8343
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They measure power factor - this is fine and accurate for loads like motors, fans, compressors.
The problem is that power supplies with power factor correction can draw current in wierd spikes.
In one case I measured a very sharp rise-time pulse, like a sharks-fin. The computer inside the meters is not fast enough to accurately read this pulse, and makes bad assumptions.
I cannot comment on the maplin one - it might or might not work. In any case, it'll likely be fine and accurate for most loads.
Just not some computers, and maybe large amps/hifi/electronics stuff.
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Ian Stirling wrote:

Do they work by somehow measuring the phase angle and just assuming it is a sine wave with lead/lag, rather than taking and multiplying instantaneous samples of A and V?
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No, they seem to sample the waveform, but not fast enough for some loads. The power supply I had would need a sample rate of around 1Khz for accurate measurement. It _seems_ to be more complex than simply assuming phase angle and a sine wave, as it accurately gets 'simple' SMPSs and loads on dimmers right.
(as measured on oscilloscope)
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The current Maplin one appears to get the measurement of PF correct. I also have a Brennenstuhl one which Maplin used to sell, and this appears to estimate the the phase shift (Ψ) and apply cos Ψ to the VA to get the power, which goes badly wrong with SMPSU's. Someone did say it works better with a battery inside it, which mine doesn't have (it died).
I made a true power meter about 25 years ago which uses an analogue multiplier, and doesn't suffer problems due to digital sampling. It only gives the true power, and has no provision for calculating VA or Ψ.
--
Andrew Gabriel
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I have the brenn* one too - it gets 'simple' power supplies - with a bridge feeding a cap, or transformer + bridge + cap right.

Yeah - but these days you can get a micro with 2 A/Ds for under a pound, and it's probably cheaper to do it that way. One blob to drive the LCD and compute the power, and track the peak power, ...
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Staffbull wrote:

The laptops will be much lower than my estimate, less than 50W a piece.
--
Grunff
http://www.greendoug.com/ - a forum for all things environmental
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I have used average of 17.9 units per day over the last year - and that includes washing machine, dryer, dish washer all on Economy 7. I have PC on most of time, TV, usual domestic appliances, fridge, etc . Most lights CFL.
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Not as formally as you. I've seriously reduced the number and length of time the computers are on, fitted CFLs everywhere we can and tried to reduce overall consumption by more concerted switching off.
Our bill for the quarter immediately passed fell about 2.5% compared to the previous year. But ... electricity rose in price signficantly over the same period.
--
Ignorance more frequently begets confidence than does knowledge: it is those
who know little, not those who know much, who so positively assert that this
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Staffbull wrote:

I've been through the same exercise. You just have to get your power metre plugged in and start measuring. In my case, the biggest unexpected use was the two amplifiers that usually got left on and used by 100W when not doing anything. I also had a couple of inefficient pond pumps which have now been replaced. Other than that, the usage was down to lots of fairly small things all adding up to a fair bit.
Interestingly, despite the government hype, the large CRT TV on standby was using < 1W
--
Matt Helliwell
www.helliwell.me.uk
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. Slightly different situation here; this is a 36 year old (two by four wood framed) all electric house in eastern Canada. Any 'wasted' heat therefore contributes, however slightly, to reducing electric heating cost. This being a cool climate there is some heating most months of the year; air conditioning of any type is rare (not needed) here. Have not replaced light bulbs with CFLs due to high initial CFL cost (e.g. around $2.50 Can, or approx one pound or more each) compared to buying four regular incandescent cheapos for around 88 cents plus tax = 25 cents (about 10-15 pence each). We replace about two packs (8 bulbs) besides any we break in the garage 'inspection light'. Over the years we have installed four foot fluorescents (new fixture about $25 = approx 12 to 15 quid?) in the kitchen and one other room which tend to be on for long periods. In the basement workshop have installed a long line of used fluorescent which turned out to have 'electronic ballasts'. They are on only while workshop is in use. With also occasionally use of a bench saw, vertical drill press and and random use of an electronics repair bench. On the main floor, residentially, while each room has it's own thermostat and individual heaters it is apparent that they come on less in those rooms where there is otherwise 'wasted heat'. For example: In the bathroom a row of six 40 watt bulbs above the vanity mirror competes with the 500 watt baseboard heater; in the kitchen the somewhat old (approx 20 years) and inefficient fridge if it wastes heat, reduces the on time of baseboard electric there. In this room two computers, printers modems etc, running continuously means that baseboard heat rarely comes on even now with minus 4 Celsius outside. One real cause of waste is however the tumble drier which shoves damp warm air outside. Being an old (i.e. much used) fairly capacious North American model it only runs for about 45 mins twice week. Clothes are washed in cold or 'mixed' water. Just a few washes per week in a 20+ year old 'automatic washer'. Electric hot water is also wasteful especially if it goes directly down the drain; although shower and bath water can be allowed to cool to room temp. before pulling the drain plug. A single 'long life' 50 watt incandescent bulb which is on, (at this time of year) for some 15 hours per night resides over the front door/ step to meet insurance/liability requirements. the nearest street lamp being across the street and down the road a bit. Total consumption, billed and paid monthly, averaged over a year is around 2000 kilowatt hours per month. Including sales tax and a monthly account charge the cost is presently $214 Can per month (approx 110 quid?). That's three to four times M.Helliwell's 18 kwatt.hrs per day; for an all electric house in a colder, longer winter and more windy climate. Ultimately this house will require more insulation, dependent on good ventilation but avoiding rot etc. Anyway just for comparison chaps (and the ladies)!
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Well what a surprise!! Not.

Yes, and came to the conclusion that it's a waste of time to fit CFLs from the energy saving perspective.
The only worthwhile application I can see for them is in outside lights which may be difficult to take apart to replace them and where the poor colour rendition doesn't matter too much.
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Andy Hall wrote:

I thought they didn't lead very long lives when out in the cold?
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