energy monitors

[Fred]

Hi,

Does anyone use one of those energy monitors that measures how much electricity you use? If you've seen my other thread about heating hot water on economy seven, you'll know I'm wondering whether to switch from economy seven.

I thought an energy monitor might be useful to let me see how much we use in the day vs. at night. Am I right to think they are just an AC clamp meter that fits on the meter tail and transmits to an LCD?

I had a read of the owl web site, the make I had found (please feel free to recommend others). Although this has a USB module, as far as I can see, it only sends real-time information, so to monitor my usage

24/7, I would need to leave my computer on 24/7. That kind of defeats the purpose of saving energy if I have to turn something on to measure what I am using!

Though you can view usage on the LCD, I think a computer link is the best way to view the data. Do you agree? Is there anything on the market which records usage and then uploads it to your computer when convenient?

If not, is it worth buying an AC clamp meter with USB output and using that to measure my usage as and when I want to? Wouldn't it be more versatile and allow me to do other jobs with it? I suppose the only disadvantage to that is that it is not wireless so the PC would have to be next to it.

TIA

[Tim Watts]

Yes - I got a free one.

I can only answer for mine - the LCD does show a daily profile, but it's fairly crap. Mine comes with a socket of the base that contains an undocumented serial RS232 output that can be hooked up to a computer.

That could be quite versatile if your meter tails are inside

[Alan]

In message , Fred wrote

You are correct about the OWL USB module. The computer connected to it has to be left on 24/7 to monitor the results. The software is rather basic and can fall over when your computer or laptop goes into screensaver/power saving mode so these features need to be turned off.

BTW, you can find the OWL USB modules for around £10 incl postage so don't pay the "RRP" for something that is probably only worth £5

I have a USB module purchased after buying ten OWL monitor and I wouldn't recommend this accessory.

You are better off finding a monitor with a built in memory that can be downloaded to computer at a later date.

I would also warn about spending a lot of money on a monitor in the first place. It is useful for determining your consumption pattern but you will probably do this in the first few days of ownership. Afterwards it will just sit there without you taking too much notice of it.

[ransley]

Individual apliances should be tested, this is an easy way to montitor things like the refrigerator to know if it needs repairs or is just a energy hog, for this I use a Kill-A-Watt meter, you plug your apliance into it, it records energy used over maybe 100 hours. For individual circuits to check for shorts, or bad wiring a clamp on amp meter that goes to .01 a is good, most sold at stores only go to .1 amp but cheap models I found at a electric supply store. For whole house monitoring you have options that connect to you meter but you wont identify problems with a whole house set up. To minimise electricty usage you need to do your own audit , I find a Kill a Watt and a clamp on meter the way to get started to know what each thing uses. once you identify the energy hogs you can make decisions on what to do next.

[chris French]

In message , Alan writes

I've recently bought the OWL usb bit. Yeah the software isn't brilliant, but it's ok. You can export the data ( per minute for historical data, per 6 seconds for the 2 minute time period live data) as a CSV file for anay

Yeah, I agree, though I didn't get it quite as cheap as that.

Are there any though? - I've don't think I've come across them. I think it depends. I already had the main Owl unit, free from the local council, I have a PC that normally runs 24/7 anyway. So it was a reasonable punt to by the usb unit. I do find it more useful to be able to go back and look at the historical usage patterns.

There probably is no reason to pay anything for a monitor. We ended up with 2 free ones - one from nPower - I'm not even a customer -though I think I just had to sign up for it (and pretend IIRC about being over 60 or something). also got a free one form the LA as part of some scheme they were doing giving out monitors to see how much they reduced power consumption. I imagine asking around would find someone with one lying around they don't use much

Our local library also hires them out for free to library users.

[Andy Burns]

Is yours one of the currentcost ones? If so, it is documented

[Peter Parry]

Doesn't your electricity meter do that?

[Alan]

In message , chris French wrote

There may be a couple at:

site doesn't give much information about what is stored and for how long on the units that do have PC connections so a visit to the manufacturers web site to download a manual may be in order.

Watch out for one of the special offers they have !!! Pay £15 more than another supplier and get an (active) data cable (circa £8 to £9) and some "free" low energy light bulbs.

[Spamlet]

There is a handy feature comparison chart of a good range of monitors here:

all seem to say they have substantial memory features, but just what that means in practice, I suggest you enquire of them.

S

[Geo]

Yes the Currentcost Envi CC128 (not Trec).

"Can I use it on my E7 or E10 supply?

Yes, the Current Cost monitor allows for two different day rates using a secondary clamp."

It can actually handle 10 different channels of RF from their clamp units.

It stores 2 hourly totals for 31 days,daily totals for 90 days, monthly totals for 84 months. It can handle 10 different channels of Rf from their clamp units. It has a kinda non-standard TTL serial output which requires their £7.50 adapter cable to interface with USB. They run an Ebay store but the unit is also available from some electricty boards.

[Dave Liquorice]

Basically yes, get the CurrentCost one it has a TTL level serial output but there is a cheap lead to convert that to USB or you can build a convertor to RS232. Live data is sent every six seconds, and historical every so often. IIRC you can also force a dump of all the data it has stored, so you don't need a PC to be on all the time to log everything.

The data is sent as XML and the formatting is published. It's fairly trivial to process. There are quite a number of 3rd party programs that can do this if you are not up to writing something yourself.

[Dave Liquorice]

True enough but that only monitors a single device, which may or may not be the one that is actually "wasting" the most power. High power things like kettles and cookers tend to be only on for short periods, so don't actually consume that much energy. It's the medium power stuff (few hundred watts) that is on for long periods that consume energy. 150W for 15hrs (old PC and monitor, TV...) 2.25kWHr, thats 45 min at 3kW. A 3kW rapid boil kettle only takes a couple of minutes when full and from cold to boil, I very much doubt that the kettle is used full and from cold over twenty times a day...

Having a decent log of actual useage allows you to plot things like this:

makes it fairly easy to spot the longer term energy users and things like coffee machines...

[Rob]

Indeed - makes it easier. Do you know the source of the c.500W background consumption? I have similar, and it /appears/ to be things like the washing machine, dishwasher, microwave etc just being plugged in - not actually doing anything. I can only account for about 60 of my

500 - but a more systematic look at it all should identify the culprits.

Rob

[Dave Liquorice]

Only about 1/2 of it, probably most is being consumed by the server and the other associated network bits and bobs. We also have a couple of lights (CFLs) that are on 24/7 or during the night. It all adds up, though TBH I'm not sure how accurate the CC is at low power levels. The clamp is fairly sensitive to position/orientation of the tail through it.

[pete]

So far as how accurate the __energy monitors are at low power, the answer for mine is "not very". I've noticed that when there is almost nothing on - computers off, TV off, lights off, heating off the first 200W or so barely makes a dent.

Although all this technology is wonderful stuff, there is still a large element of "know your problem" to identifying __wasted power consumption. Things like: what goes on in the kids' bedrooms? Has that light in the loft been left on for the last 6 months? Are you taking things for granted - such as a pond-pump that runs 24*7? Do your security lights spend most of the night switched on ('cos next-doors cat likes to sit right under the sensor?)

[Huge]

Which is why I have a tell-tale neon in the landing ceiling.

[Vortex7]

To make that call I don't think you need any fancy technology, just a couple of years' meter readings (do you keep your old bills?)

With E7 day rate is about 15p; night rate about 5p.

On a "normal" tariff you will pay about 10p/unit.

Therefore if your day units used exceed your night units used then there's no point in E7.

[Fred]

I have my old bills but they were pre-children, so our usage has changed since but I agree, a month or two of observing the meter might answer some of my questions. The disadvantage of relying on the meter is it tells you what was used in a twelve hour period. These monitors allow you to see minute by minute. I suppose on a cost basis it doesn't matter whether 6kWh is one hour at 6kW or 6 hrs at 1kW but knowing that would help identify what was using the power.

MY day units always exceed my night units. One price comparison site said the national average was 40% night : 60 % day, so most people's day units exceed their night units. I think hose figures must be for people with storage heaters. My only night heating is a 3kW immersion heater, so our night: day ratio is even less. Last time I worked it out there was not much difference whether we were on economy 7 or not. I need to do those calculations again. If I switch off the immersion and use oil, there would be no reason to keep the economy 7.

[Fred]

I hadn't heard of the other makes, so I'm off to research the other links people gave - thanks.

I was puzzled by the above. My understanding was that the owl would not upload historical data; only real time usage. Are you saying that it does?

Thanks.

[Fred]

I've had a quick look but though I could find multimeters with serial or usb outputs, I couldn't find any clamp meters with them. I did see some probes you could buy to convert a multimeter to a clamp meter; I think you set the meter to read voltage and they output 1mV per 0.1A or something like that. I don't know how good they are though.

Another thought is what powers the serial output? If it is the multimeter, how long would the battery last if on continuously? Perhaps a purpose built module is the answer after all?

Thanks.