Energy Meter use or ornament?

[ericmark]

I have two energy meters one for the whole house, and one for plugging into sockets, the advantage compared with all other meters is it includes time, the whole house one to me is an ornament, however I have from time to time used the plug in one to test what is being used over a fixed time.

I went around plugging it into all sorts of items, but although one may find the Sky box uses a lot of power it makes little difference we still use it.

With items like the washing machine, again no real point knowing how much power it uses per wash, as it does not make a scrap of difference on which program my wife uses. I also used it on my fridge/freezer and freezer again to little point we did not unplug one as a result.

OK mothers freezer it actually highlighted it was not turning off, turned out the thermostat was faulty, but it did not read out "faulty" it needed some interpretation of the readings. Motor used 28 watt and 0.67 kWh per day so 28 x 24 = 672 so clearly it never turned off. I tried to find a thermometer to see what the temperature was, but could not find any in local shops, then my brewing thermostat arrived and it showed - 24°C so new thermostat ordered and fitted, but not really the sort of job a normal DIY guy could tattle.

I also used it to work out what size of heater I needed for my brew fridge. 18W heater used for 24 hours used 0.09 kWh so 3.7 to 4.2 watt, but since only 2 decimal points it is only an approx value.

It shows power factor, but really can’t see anyone using the information to correct the power factor? So in the main mine does very little that my clamp on multi-meter would not have also done. So though not completely useless, I really don’t use it much. I actually wrote a java script program to give average kWh and capacitor required to correct power factor, but never really used it.

Basic fact if we use something electric it costs, so only use what we need, does not need an energy meter. Or have I missed something, is there really some point testing out appliances to see how much they use?

 

[Iggifer]

I think whole house meters, or even smart meters, are more useful than single appliance meters.

I put a clamp meter round my tails a while ago, and was amazed at the difference between what I would normally have on, and then turning off what I could do without. It's more about attitude than actual readings though I think, if you want to save money.

If you want to be frugal with electricity, you can do it with or without a meter, you just need to remember to turn things off when you leave a room.

 

[JohnW2]

If you want to be frugal with electricity, you can do it with or without a meter, you just need to remember to turn things off when you leave a room.

... although, at least in the case of some loads, you may have to factor in the possible effect on life expectancy of appliances/equipment when they are frequently switched on and off.

Kind Regards, John

 

[Iggifer]

If you want to be frugal with electricity, you can do it with or without a meter, you just need to remember to turn things off when you leave a room.

... although, at least in the case of some loads, you may have to factor in the possible effect on life expectancy of appliances/equipment when they are frequently switched on and off.

Kind Regards, John

True. And for that very reason, I haven't really turned my Mac off on a daily basis for 10 years, and it's still going strong. Through no fault of it's own, it's really now been retired to use as a 15TB NAS, but still gets occasional use. I doubt I would have seen 10+ years life out of it if I'd turned it off and on every day. Just the thermal cycling alone wouldn't have been good for it.

 

[winston1]

The clamp on meters do NOT measure energy. They are not fit for the purpose for which they are sold (or given away). They measure current only and display watts assuming unity power factor and a fixed constant voltage (which on some you can specify). Voltage is never constant and power factor is rarely unity. I really don't know how the manufacturers of this rubbish have got away with hoodwinking the public for so long.

 

[JohnW2]

True. And for that very reason, I haven't really turned my Mac off on a daily basis for 10 years, and it's still going strong. Through no fault of it's own, it's really now been retired to use as a 15TB NAS, but still gets occasional use. I doubt I would have seen 10+ years life out of it if I'd turned it off and on every day. Just the thermal cycling alone wouldn't have been good for it.

Indeed - and as well as the long-term effects of thermal cycling there are the 'switch-on stresses'. I have only rarely experienced an item of electronic equipment or a lamp/bulb etc. suddenly dying whilst running, but such deaths are common at switch-on.

Kind Regards, John

 

[DaveHerns]

Ericmark, what does your Sky box use? The router is rated 40 odd watts and I think I posted in the Audio forum whether that could be used all the time and they said it wouldn't be. I'm not convinced.... Maybe I should turn it off at night

 

[endecotp]

You can get a good feel (literally) for how much power something is using by feeling how warm it gets.
Imagine an old 40W incandescent light bulb, in a box. How hot would that get? Pretty hot. If your box of electronics is not that hot, it's not using 40 Watts.

 

[JohnD]

I use an Owl. It is not accurate below about 500W when there are just fridges, PC, lights and a few things on standby, but the display goes up and down by the right amount when an electric heater, such as a washer or tumbledrier, starts, or a kettle is turned on, so it is adequate for cost tracking and wasteful use.

Modern energy-saving lighting and fridges use so little that the cost is not worth worrying about. You can light a room with a couple of 10W LEDs.

 

[winston1]

I use an Owl. It is not accurate below about 500W when there are just fridges, PC, lights and a few things on standby, but the display goes up and down by the right amount when an electric heater, such as a washer or tumbledrier, starts, or a kettle is turned on, so it is adequate for cost tracking and wasteful use.

Modern energy-saving lighting and fridges use so little that the cost is not worth worrying about. You can light a room with a couple of 10W LEDs.

Well as I said they don't take account of power factor other than unity and don't take account of the instantaneous voltage. Electric heaters have a power factor around unity. Energy saving lighting and fridges have a low power factor hence the error.

 

[JohnD]

Or, as I see it, it is accurate enough for anything that matters.

 

[ericmark]

The clamp on meters do NOT measure energy. They are not fit for the purpose for which they are sold (or given away). They measure current only and display watts assuming unity power factor and a fixed constant voltage (which on some you can specify). Voltage is never constant and power factor is rarely unity. I really don't know how the manufacturers of this rubbish have got away with hoodwinking the public for so long.

My plug in meter can be set to VA or Watts and also displays power factor it is a WorkZone as to if it works out taking into account all things measured I don't know volts range 190 ~ 276 and Hz range 40 ~ 70 but what makes it an energy meter is the fact it measures time. My clamp on will measure amps and volts but not time. So for example I can plug in the bread maker and work out what it costs to make a loaf of bread and compare it with a pre baked loaf. However my point is once you have bought a bread maker you will use it, you can't really go around shops and ask them to make a sample loaf with the meter plugged in.

Ericmark, what does your Sky box use? The router is rated 40 odd watts and I think I posted in the Audio forum whether that could be used all the time and they said it wouldn't be. I'm not convinced.... Maybe I should turn it off at night

The TV stuff should follow the 1W voluntary limit on stand by power usage, but the sky box has a problem, it monitors program changes and to do that it has to power up the LNB as to if both inputs from LNB not sure, from measurements it seems it has two levels at least of stand by and every so often I hear the hard drive fire up. Since I now record programs with the PC it does not go into stand by very often and it was the old box I measured, It draws 22 watt run and 17 watt stand by to start with dropping to 12 watt it is so long ago can't remember the average. The free to air box even when programmed to auto start up to record a program took less than the energy meter could record. It was the power used by the sky box in stand by which resulted in us leaving it on as so little saved and if not in stand by when you switch on TV and see an interesting program you can go back to it's start then miss the adds slowly catching up.

When I first got it I was interested in testing things specially the fridge and freezer, but in real terms it caused me to switch things off less rather than more as I realised how little (except for sky) stand by mode costs.

 

[ericmark]

Just found my records sky box idle 0.05 amp and run 0.07 amp I made note "Under test when left for a while on standby the currect dropped to 0.04A but raised to 0.07 as record started flitted between 0.06 and 0.07A both on run and standby." Computer power factor 0.95 one small freezer showing a power factor of 0.33 with the freezers the max watts showed 2708 run at 115 and idle at 30 until we swapped for a inverter type where then max watts was clearly the power used on the defrost cycle around 110 watts the run watts not steady seemed to vary between 40 and 60 watt it would seem there are valves which direct to fridge and/or freezer so motor power varies according to what is being cooled. So with the inverter fridge/freezer the energy meter is the only way average at 48 watts or 424 kWh/annum.

However my point is knowing what it uses in the main does not change how it is used. So why bother to measure?

 

[ericmark]

I use an Owl. It is not accurate below about 500W when there are just fridges, PC, lights and a few things on standby, but the display goes up and down by the right amount when an electric heater, such as a washer or tumbledrier, starts, or a kettle is turned on, so it is adequate for cost tracking and wasteful use.

Modern energy-saving lighting and fridges use so little that the cost is not worth worrying about. You can light a room with a couple of 10W LEDs.

Well as I said they don't take account of power factor other than unity and don't take account of the instantaneous voltage. Electric heaters have a power factor around unity. Energy saving lighting and fridges have a low power factor hence the error.

Ups seems I got it wrong, yes the meter which measures all power used in house does not have any method to measure volts so it can not do power factor or watts it can only measure amps and if it does display watts then it assumes 230 volt it is not real watts. The plug in type is however very different it does measure power factor, hertz, volts, watts, VA, and the important bit time.

 

[big-all]

i have have had a plug in meter for around 20 years
has it payed for its self probably not as it cost £20
is it useful yes very useful do i need it to work out that a 20w fluro bulb uses 80% less energy than a 100w then no
but where it does help i have 2 identical size tvs one uses 44w the other uses 100w so swapped the most used to the main room also if i use a second monitor to watch catchup tv off the laptop because its a few inches away the picture is a similar size to the 44w tv but at a 20w consumption but at the compromise off poor sound quality
also handy with led bulbs where the consumption can vary wildly i have some 4w off one sort and 4w off another with identical light output one sort uses 2.2-2.4w the other uses 4.2-4.4w
i also worked out a washing machine left on standby for a whole week about 8w or 1.34kw uses more power than the 1.1kw for a 60min 40degree wash

in short will buying one save you money i doubt it will it tell you what actions are worth the effort then yes
i unplug the printer as its seldom used but uses 7w on standby
same with the washing machine
i also unplug all tvs and connected boxes in rooms not in daily use
but on the same level i leave all lights on in the main part off the house in use
i also experiment
which is quickest which is cheapest
a 900w microwave and a mug off water
or the same mug off water in a 2750 kettle
answers please