# Just how much power can a fan oven consume...?

Folks,
We've recently moved and I've finally got around to checking the flat's energy consumption.
So I start this morning:
08:00 'day' meter reading 8159 09:00 'day' meter reading 8160 10:00 'day' meter reading 8161 11:00 'day' meter reading 8162 OK, one unit or so an hour 12:00 'day' meter reading 8166 What??? 13:00 'day' meter reading 8167 Back to one unit an hour
What happened between 11:00 and 12:00? My wife put the fan oven on for 15 minutes, to heat up a pie. That's right - 15 minutes. Nothing else in the flat changed during that time.
How can a fan oven consume 3 kw hours in fifteen minutes? It's a run-of-the-mill single Bosch fan oven - that's a 3 or 4kw load rating?
To my understanding, the figures suggest the oven was running at 12 kw for that quarter of an hour (some 48 amps) which doesn't seem plausible.
My first thought is that the meter is faulty, but I'd like to know of other possibilities.
Can anyone offer enlightenment?
Many thanks, Peter
P.S. This wasn't a fluke. Mid-afternoon, I ran the oven for another 15 minutes and whoosh, another four units gone over the hour (ie the base load plus three).
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Is the meter realy displaying kWh?
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On 28/02/2013 21:48, charles wrote:

Our Siemens one says "KWh" on it, no decimal point either just a flashing led.
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On 28/02/2013 21:40, Peter Kemp wrote:

TBH a kW standing load seems a bit high too... have you tried turning things off to see what it does? You ought to be able to get it to negligible (clocks only) without too much trouble, then turn on a couple of lights of known power...
Andy
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On 28/02/2013 21:59, Andy Champ wrote:

1kW standing load here too, it's surprising how quickly multiple small loads add up. I did the usual of turning everything off to check and then just turned them back on for convenience. If prices go up further than they are going to stay off for longer....
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Lee wrote:

320W here right now, with fridge/freezer not actively running (think it tends to be a 1:3 duty cycle).
A quick run around, turning "unnecessary" stuff off, only dropped it to 290W, most of which is likely to find itself being left on again inside a week, for the £30/year it'd save.
I know if I turned the server off the rest would drop to just North of 100W for the UPS, PDU, ADSL router, WiFi AP, DECT base-station, Ethernet switch, TV loft amp, clocks on ovens, emergency lighting chargers, PIR detectors, phone charger and not forgetting the energy monitor!
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On 01/03/2013 11:34, Andy Burns wrote:

In terms of background use, the FF is the biggest culprit for us (it's old and worse we like it cold, @2C), followed by a pair of SkyHD boxes and then the usual complement of NAS,modem,router etc...
Lee
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wrote:

Simple, it can't.

Possibly only a fraction of that, many Bosch single ovens are less than 1kW.
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Thanks for the thoughts so far:
1 I agree a standing load of 1Kw is kinda high and needs investigating. The issue with the cooker became my first priority.
2 When I quoted kilowatt hours, I was assuming that the meter's units were kwH. Is that not the case?
3 The oven was on for fifteen minutes in total. It's a fan-assisted oven, so it gets to working temperature pretty quickly. When turned off, the fan continues to run for about five minutes, but I've assumed that's trivial consumption.
We're going to shut down the house completely tomorrow (apart from the fridge) before going out shopping for a couple of hours. I don't expect the meter to budge. When we get back, the oven goes on for fifteen minutes while I stand and watch the meter. If another three units go up in smoke during that time, I guess it's a phone call to EDF.
Wish me luck!
Regards Peter
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In article

It might not be. Have a good look at the front plate. Mine is labled as a "Watt Hour meter"

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Peter Kemp wrote:

Phone EDF? Brave man.
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AC

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On 2013-02-28, Peter Kemp wrote:

We have a fairly new (last summer) fan-assisted oven connected through a plug. It draws 2.5 to 2.8 kW when switched on, then drops back quite a bit, occasionally going back up (especially after the door's been open).
(I really like this oven, too. It has nice features like automatically switching the internal fan off when the door is open to conserve heat a little.)
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I remember once reading of someone who switched the oven off at the main switch after they had used the oven as a fan kept running! Eventually the conrols suffered from the heat.
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On 2013-03-01, DerbyBorn wrote:

That would have been OK with the old one. When you switched it off, it stopped doing anything (except running the clock, of course). The new one (I guess this is standard now) has an external fan that runs for a while, as you say. We've become able to tell from the knob position at a distance that it's off.
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Peter Kemp explained on 28/02/2013 :

With no decimal point, the three, could be just over one. If you switch on just before the number is about to click over and switch off, just after it has clicked over, your 3Kw might actually be no more than 1002 watt / hour.
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Regards,
Harry (M1BYT) (L)
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In article

I'm guessing the pie said heat for 15 minutes. How long was the oven left on to warm up? What sort of hob do you have? Electric rings can use a lot if something was also heated on the hob.

The heat from the oven and much of the heat from a hob all goes into heating the house, so if you do generate 4kWh from these, your heating system (if it has suitable controls) will demand 4kWh less than it would have done.
As Andy said, a base load of 1kW is quite high. Mine is around 500W, and that's with more always-on equipment than I would expect most people to have, although it is averaged over whole quarterly billing periods, not just the middle of the day.
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Andrew Gabriel
[email address is not usable -- followup in the newsgroup]
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Yes, I agree the meter sounds like its not reading what you think it is, its obviously working to a different unit than might be expected. I did ask this question once and never did get an answer I could understand. Basically they said the meter serial number tells us how to interpret the reading. Which means, in my book if I could read it myself, which I can't, how the heck could I calculate the usage if I did not know what its unit of measurement was in the first place.
Brian
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Brian Gaff....Note, this account does not accept Bcc: email.
graphics are great, but the blind can't hear them
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Peter Kemp wrote:

If there was some manual dishwashing done at the same time, a boiler may have kicked in, too.
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On 28/02/2013 21:40, Peter Kemp wrote:

1 kWh ambient is a lot, especially if it doesn't include heating. That's £1500 a year on its own. I'd look at your method of measurement first.
Rob
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On Fri, 1 Mar 2013 02:38:43 -0000, Arfa Daily wrote:

ent

Doing the maths backwards 17p/unit. Which is perfectly possible to have
these days even with a "standard" tarrif. Our E7 day rate is 18.78 + 5%
VAT...
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Cheers
Dave.
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