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# 136566 2-Dec-2013 09:51
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My power bill's reasonably high - $120 in summer (may go up if we run air con more), $350 in winter, for two people. We have a 3 bedroom house, two heat pumps, and we keep it pretty warm in winter. We cook twice a day, we use the clothes drier, computers are always on, etc.

I'm interested in getting some real metrics on what the power's used for. A permanent solution probably isn't necessary, but something that can measure and graph usage for key appliances over the course of a week or so would be interesting. Hot water would be a key one, and obviously I can't use a plug in meter for that. I don't know how I'd measure lighting since it's hard wired, and if I had to have plug in devices for everything I'd probably need 15 of them, which sounds expensive.

Does such a product/solution exist? Ideally something easily removed, that way I could use it occasionally and loan/rent it out to others to use when I don't need it.

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  # 943964 2-Dec-2013 10:39
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There is no easy solution without spending money maybe a lot. I had a look at this years ago. I'd be interested if anyone else has found an easy and cheap solution to this.

If you have a smart meter you might be able to get hourly readings from your electricity company. That would help with overall usage so you'd then just have to allocate that usage across the individual devices usage. It might be quite simple to approximate if you use the same equipment at the same times each day. The cost of other metering options may mean that you decide to do some manually estimating to determine how much is used by each device:
lighting is simply watts x time on
computer equipment can be approximated in a similar way if left on all the time.
heat pumps and hot water are more variable but you usually know when heat pumps and other heating are used

When it comes to metering by device that is much more difficult unless it is plugged into a 3-point socket. Meters for that are $20 or so. Permanently cabled equipment is more difficult to meter. Spot metering is cheaper, continuous metering is usually a lot more expensive. For example, one of your options is a (or clamp-on) power meter. They close around a power cable and measure what is happening on that cable. You can move it around the hot water heater, heat pumps and even the mains cable and measure each one at a time. Most are used for electrical continuity and line quality testing but you'd want one that records power usage over time. That will probably be much more expensive. You can buy basic units for line testing under $100 (you;d calculate power as the product of volts and amps) but most are several hundreds and continuous logging using cost $1,000+.







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  # 944002 2-Dec-2013 11:16
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I've got one of these and can recommend it for basic metering.
http://efergy.com/nz/products/energy-hubs/engagekit-hub

When I first installed it I used a single clamp and moved it from one fuse to the next monitoring and turning on\off everything connected to that fuse.  Once I got bored of that I connected up both clamps (2 phase supply to house) and monitor everything together.  After a while you can look at the graph and know whats been turned on to cause that spike etc. 

The most interesting thing I found was that the garage lights (6x single tube fluro) together consumed 800w! We used to leave these on when we went out for an evening. I quickly rewired an existing switch and hooked it up to a 10w LED instead, now the fluro's barely get turned on.




Speedtest

 
 
 
 


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  # 944007 2-Dec-2013 11:20
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I've been thinking about trying the Ubiquiti mFi current sensor. Similar concept to engagekit, just wrap it around the phase cable. This is the problem however as you will need to split the phase cable from the neutral which is tricky and potentially dangerous. Perhaps just turn one thing on and check the meter after an hour?







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  # 944063 2-Dec-2013 13:01
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Ah so it looks like there's no really good way to do this. I was hoping there would be some combination of clamps, plug in devices, and monitoring software that would do the job. There probably is, if you want to spend thousands, which is why I wondered if renting would work.

I think I'll park the idea for a few more years.

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  # 944108 2-Dec-2013 13:45
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http://centameter.co.nz/

I had an electrician install this --- wasn't keen on getting behind the powerbox.

It does work well though -- it detects the increase in power use from a single light going on. 

My summer bills are around $300 (power+gas), up to $600 in winter. I was previously on trustpower, and, had a couple of $900 bills.  Dumped them quicksmart.



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  # 944113 2-Dec-2013 13:51
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surfisup1000: http://centameter.co.nz/

I had an electrician install this --- wasn't keen on getting behind the powerbox.

It does work well though -- it detects the increase in power use from a single light going on. 

My summer bills are around $300 (power+gas), up to $600 in winter. I was previously on trustpower, and, had a couple of $900 bills.  Dumped them quicksmart.

 

 

 

The Centameter website is reallys short on information. I'm not sure how much benefit I'd get from a single measurement device.

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  # 944115 2-Dec-2013 13:57
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timmmay:   The Centameter website is reallys short on information. I'm not sure how much benefit I'd get from a single measurement device.


Yeah, i bought it at the homeshow a few years back.  Basically, it measure the houses total current draw in realtime. 

Then, you can go around the house switching various things off/on to see the effect on current draw.   The problem is with on/off devices such as fridges/thermostatic heaters& coolers -- you have to check the reading when they are on. 

I guess you could go to your power board and selectively power up the house to see which circuits are using the most power. Then, you can test individual items on the circuit too identify high power culprits. 

I've found it really useful, and is quite cheap. 





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  # 944121 2-Dec-2013 14:06
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Sounds interesting, but I don't think it would tell me what I want to know without significant effort.

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  # 944348 2-Dec-2013 20:18
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timmmay: Sounds interesting, but I don't think it would tell me what I want to know without significant effort.


I found that a combination of a cheap plug in power monitor and the household monitor was the best for identifying the energy hogs in the household.  MySky decoders are a big user as are older fridges and freezers.  You can get a household monitor like the Centameter or an equivalent at Jaycars at a reasonable price, USB connectivity to a PC is useful.  It does take some effort to save power.

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  # 944357 2-Dec-2013 20:29
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I have three of the Belkin Conserve Insight power monitors that are brand new in the original packaging. See the link for more info:

http://www.elive.co.nz/belkin-conserve-insight-t22695.php

Make me an offer for one or more if you are interested.



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  # 944362 2-Dec-2013 20:39
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I have a plug in power monitor already, a cheap warehouse one. The belkin looks a bit better, but I'd say the one I have is good enough.

I did discover I was paying $120 per year or more for having each of my TVs and such on standby. I fixed that pretty quickly and easily.

I suspect air conditioning and hot water are the major users of power, plug in meters won't help with that much. Whole house monitoring probably would show them up, for example first thing in the morning when we shower we'd see the usage spike as it heated the water. And honestly I'm not about to reduce the length of my showers, I'm looking for wastage not use.

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  # 944381 2-Dec-2013 21:07
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timmmay: I have a plug in power monitor already, a cheap warehouse one. The belkin looks a bit better, but I'd say the one I have is good enough.

I did discover I was paying $120 per year or more for having each of my TVs and such on standby. I fixed that pretty quickly and easily.

I suspect air conditioning and hot water are the major users of power, plug in meters won't help with that much. Whole house monitoring probably would show them up, for example first thing in the morning when we shower we'd see the usage spike as it heated the water. And honestly I'm not about to reduce the length of my showers, I'm looking for wastage not use.


Agreed, waste is top of the list, no need to live like a monk.  About all you can do to save HWC power is reduce the cylinder temp a few degrees with the thermostat setting, but not so low that you start your own bio-warfare laboratory.  The same with aircon temp, every degree differential between ambient and heated space costs $$.  I do recommend a HWC heat pump installation as a major power saver if your HWC usage is appreciable.  I would fit one if I didn't already have solar water panels.  Insulation is the big saver.



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  # 944383 2-Dec-2013 21:14
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I have a lot of insulation, but it's an older house and it's just not constructed with that in mind. Double glazing, thick carpet and padding, under floor, wall, etc.

I can't change my hot water temperature. I have a brand new mains pressure system and they tell me the only settings are on or off. The temp on the output is controlled by mixing with cold water. I have an insulation blanket over it, but there's apparently not much point with the new cylinders anyway.

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  # 944388 2-Dec-2013 21:14
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There are a few options similar to the centameter - usually north of $100 and with a clamp sensor that you normally fit on the incoming phase in your switchboard.

For your needs you could get one of these and clamp it over the phase going to the heatpump or hot water (these will be on a dedicated circuit). I suspect measuring one appliance at a time isn't what you were hoping for, but if you monitored the heatpump for a week, then the hot water the next week say, you'd end up with a pretty good idea of where your power is going.

This will require you to poke around in the back of your switchboard - you can't just clip the clamp meter onto the white insulated cable in your ceiling or going into the hot water cylinder for example, unfortunately.

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  # 944424 2-Dec-2013 22:30
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Do you have a smart meter installed?

We do, and this gives us two things. Firstly, Genesis Energy provide an app which shows power usage broken down by the hour. This is a couple of days behind, but you can get a pretty good idea of what is using the power, I can see when the hot water heating comes on, and when dinner is being cooked.

The other thing it gives is an instantaneous readout of current power draw. It cycles through them, but you can also push a button to got to the screen you want. If you have two people, you can get one person to switch things on and off, while the other monitors the power usage. You only really need to do this once, I don't see why you would do it on a daily basis.

If you don't have a smart meter, you could try ringing up to see if you can get one, or to see if another power company such as powershop would put one in for you if you switched to them.

And one final point, for us, we use roughly 10 KWh of hot water heating per day. We have a 300 litre tank, and this easily lasts us a day. For us, switching to a day/night plan, and configuring our line to only heat the water at night, means that it costs $1 per day to heat water, rather than $2 per day if we were on an anytime rate. It cost us $61 to reconfigure the our meter to day/night and change the boost option, but the payback period was only two months, so it was well worth it.


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