Smart Meter and Home Energy Monitor Shows 2.3kW Spike Every few Minutes?


Postby Peter_B » Thu Dec 03, 2015 3:34 pm

I've just had a smart meter and home energy monitor fitted to my house and the home energy monitor has instantly thrown up a complete electrical mystery.

Every 2 minutes and 20 seconds, almost to the second, the home energy monitior shows a 2.3kW load switching on for between 3 and 5 seconds then switching off again. It doesn't matter what else is on in the house, for instance if the kettle or the toaster is on at the time then this mystery 2.3kW kicks in every 2m 20s over and above their load.

I have tried a process of elimination by switching of one at a time, our indoor fridge freezer, our garage freezer, my computer and all its periherals and everyhting else I can think of yet this mystery 2.3kW load keeps coming on every 2m 20s.

I am completely at a loss to know what this load is and I should be most grateful for any suggestion as to what it might be.

Thanks
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Postby ericmark » Thu Dec 03, 2015 11:25 pm

I would turn the breakers off one at a time and find which circuit first.
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Postby Peter_B » Sat Dec 05, 2015 10:27 am

This is embarrassing!!

My wife has a craft room in an outbuiding that I fixed up for her a couple of years ago. She hasn't been out in her craft room for a while because it's been pretty cold and anyway it has a 'kill switch' by the door which knocks everything off in there and that's why I didn't bother to check it. But when it was the only thing left I went over there and.......yep........found the kill switch was on and there was an iron plugged in and switched on, and we reckon it must have been like that for several days. We had a discussion about that !!

So I think I've discovered another interesting use for a home energy monitor apart from telling me what I'm using each day.
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Postby ericmark » Sat Dec 05, 2015 2:57 pm

Thanks for the reply. I bought a plug in energy meter. And I started to test what items around the house used. One item which was highlighted was the sky box, which unlike any other item going into stand-by mode used far more than the 1 watt limit because it kept the LNB energised so it can down load program changes.

The main point was items like the washing machine, dish washer, fridge/freezer and freezer I have for years been telling my wife bulk buying does not work because of the cost in storing the items. It costs around £300 a year to run a second freezer.

However when doing the monitoring I found my mothers second freezer was drawing 28W and using the energy rating info it should run for around 30% of the time. However calculating we found it to be running 103% of the time. Clearly an error as could only run 100% but also clear it was not turning off.

There were two possible causes. 1) Insulation break down. 2) Thermostat stuck. I wanted it to be the latter easy enough to change a thermostat. But question then was how to find out what temperature it was running at? I tried every food shop and freezer shop I could and it seemed no one sold thermometers to measure -18ºC. However than a break through found brine freezes at -18ºC so it was a tray of salt water in freezer and did it freeze or not. It did freeze solid so it would seem getting too cold.

The 32 litre freezer only cost £100 new, but when I phoned around I got quotes of £40 just to test it never mind do a repair saying I would deliver it did not help, seems they all work out of back of van and have no workshop as such.

So it was DIY or nothing. On the internet I located a replacement thermostat for less than £5 as the same time I wanted to start brewing beer with temperature control so ordered up an electronic sensor as well about £14 which would also measure -18ºC so I could set the new thermostat.

The electronic sensor arrived first so it was used to control freezer until the correct thermostat arrived. However when it did arrive the shaft was too short so had to set temperature and lose the ability to change it. In fact on coldest setting was only -16ºC seems the place where the sensor goes was too close to the cooling parts so did not measure air temperature but the shell temperature at top of freezer. Anyway it was good enough so all running again.

However at £100 for new considering all the messing around not sure it was really worth all the effort. I have that niggle in back of mind the freezer was never right from new.

I did the calculations on the other freezers both mine and mums and decided with an expected life of 7 years it would never be worth replacing a unit because it was inefficient. When it fails buying a better replacement yes may be.

However as I went into it I realised there were other factors. A non auto defrost freezer has the active parts spread around the box, as a result you can't get extra room for Christmas turkey by removing draws. Also the temperature is a little bit of pot luck, there is nothing to circulate air so some bits can be colder than others. The auto de-frost however has a circulating fan so all parts at same temperature and you can remove draws for large items.

So it seems all this careful monitoring is to no avail, yes like you it found one fault, but in the main does not matter if sky box uses too much on stand-by we like the problems offered so still have sky. A cheap non auto-de-frost freezer may use less power, but not willing to take the risk that food is not cold enough in some areas so still got a frost free model. Hope it lasts more that 10 years although that is the warranty on the motor and inverter. We also selected a model which shows the temperature both fridge and freezer so we are aware if any power cut has allowed temperature to rise.

So in real terms there is no need to know the power we use, just simply switch off when not in use.
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