Energy v cost, do people really not know the difference?

[Jurassicspark]

My "900W" microwave 1600W in use

900W as in the magnetron output, and the net wattage conflating all other components such as the fan, turntable motor, losses, relays, and whatever new gubbins nowadays?

Definitely not.

Or 900W as the lowest and 1600W as the highest mode selected?

Or 900W consumed from the mains and 1600W output?

 

[JohnW2]

Depends on the food. I’m sure it’s advised and recommended on which method of cooking is the best.

Indeed and, given that the microwaves essentially only heat water molecules, I imagine that it probably is the water content of the food which is the most important factor. Compared with other methods of heating/cooking food (e.g. a conventional oven) a microwave oven would presumably be pathetic for trying to heat very dry foodstuffs

But is it much greater here considering the trivial amount consumed by standby.

I agree, since the standby power is so trivial in comparison with the 'in use' power. However, the principle I mentioned still holds - a member of my family "doesn't really believe in microwaves ovens", but was given one as a present, and probably just uses it for a minute or two once every several months - so the standby power consumption might, in her case, be a bit closer to her 'in use' consumption

 

[morqthana]

The kettle is (almost entirely)stainless steel, but much lighter than the 4-5l pot I used on the hob.

 

[JohnW2]

The kettle is (almost entirely)stainless steel, but much lighter than the 4-5l pot I used on the hob.

As I suspected. Try feeling the kettle and pot a short while after you've poured all the water out - and I think that would probably give some insight into the difference between how much ('wasted') heat energy had been dissipated in the respective vessels

 

[Why Not Indeed]

Or 900W consumed from the mains and 1600W output?

That would be quite the miracle, wouldn't it? 1600W consumed, the label says 900W. I assume it's at 100% power. The only button that works is the "Start" button, so all I can get is the defaults, in 30s increments!

 

[SUNRAY]

I went round my sons and my daughters homes a while back when this very discussion cropped up, in fact it cropped up originally in our house when daughter wanted TV on and asked for new remote batteries as we power down almost everything apart from PVR 's, router, dect phones, usb 13A sockets, outside PIR's
In my daughters house there were over 100 items either in standby or otherwise consuming energy, 40A clamp on main tail shows standby ~2A ~11KWh/day
In my sons house around 70, ~1A / 5.5KWh/day
In our house I think it's 10, ~ 40mA / 240Wh/day - I feel this is a bit low for mine but I used a very cheap meter with only 2 decimal places so potential for greater error at such a low current but this is more about comparisons rather than definitive values.

 

[flameport]

The microwave standby thing is a long standing mythical piece which surfaces regularly.
There could be some truth in it but only if the microwave was rarely used.

For the microwave which was looked at a few years ago, it used 5kWh per year in standby if left on permanently.
With 1400W when in use, provided it was used for at least 215 minutes per year or just over 4 minutes per week, the cooking usage would be more than the standby.

Either way the actual costs for it on standby are tiny, a couple of pence per week.

 

[JohnW2]

The microwave standby thing is a long standing mythical piece which surfaces regularly. There could be some truth in it but only if the microwave was rarely used.

Indeed - but I suppose that a microwave oven might get closer to that truth than almost anything else, since it's probably one of the very few household appliances which (in just a tiny proportion of cases) may be left on standby continuously but virtually never used.

For the microwave which was looked at a few years ago, it used 5kWh per year in standby if left on permanently. ... With 1400W when in use, provided it was used for at least 215 minutes per year or just over 4 minutes per week, the cooking usage would be more than the standby.

I'm sure that the family member I mentioned doesn't use hers for anything like 215 minutes per year, probably no more than a tenth of that, if that. However, as you go on to say, it's all ridiculously trivial, because ...

Either way the actual costs for it on standby are tiny, a couple of pence per week.

 

[morqthana]

In my daughters house there were over 100 items either in standby or otherwise consuming energy...
In my sons house around 70...

100??

70??

How?

 

[Munroast]

70 & 100 seem ludicrously big numbers, can only think of 1 in our house

but do remember all these devices on standby are micro heaters, and for at least 9 months of the year that heat contributes to you CH. so a microwave on standby using 2w is providing 2watts of heat -

 

[ericmark]

Kettle 2.7 kW and the induction hob 3 kW, and we filled the kettle to mark poured in into a pan with a glass lid, refilled kettle, both turned on together and took near exact same time to boil.

We did this after doing the same with a 5 kW gas hob and kettle in the daughter's house, and the kettle was twice as fast, clearly now we are cooking with gas, means doing it slowly.

I realise I have around a 200 watt load, which I can't explain. At the moment, using 350 watts, half of that is down to freezers, fridges etc. We have far too many, running 4 at the moment, but they do not add up to 350 watts. I must test, I have 4 circuits with sockets, can only really test three of them. Forth is an UPS supply and no handy place to put a clamp on meter to measure.

The immersion heater could account for some load, but at this time of day, it should not be using current. So latter today I may go down to the flat under the main house, and put the clamp meter on the tails to consumer unit, and see which circuits are using power, and how much, but with a really low electric bill, last time I looked, it was a minus bill, I am not really worried.

 

[JohnW2]

70 & 100 seem ludicrously big numbers, can only think of 1 in our house

It does sound pretty extraordinary,and certainly extremely 'atypical'

but do remember all these devices on standby are micro heaters, and for at least 9 months of the year that heat contributes to you CH. so a microwave on standby using 2w is providing 2watts of heat -

Indeed, I mentioned that above. However, as I also observed, although that means that there is no 'wasted energy' during those 9 months (or whatever), there usually will be 'wasted cost', since than 2 W or whatever of heat would otherwise be derived from a much cheaper sourcethan electricity (usually gas). However, in terms of nearly everyone's 'big picture', the amounts of money are so trivial as to not really justify time spent thinking (or typing!) about it

 

[JohnW2]

Kettle 2.7 kW and the induction hob 3 kW, and we filled the kettle to mark poured in into a pan with a glass lid, refilled kettle, both turned on together and took near exact same time to boil.

That does rather surprise me - morqthana's reported experience is far more as I would have expected. What material was the kettle made out of, and how heavy was it in comparison with the pan?

We did this after doing the same with a 5 kW gas hob and kettle in the daughter's house, and the kettle was twice as fast, clearly now we are cooking with gas, means doing it slowly.

I would imagine that the transfer of energy with an induction hob is a lot more efficient than transfer from a gas flame (which is more likely to heat the whole room ).

 

[Munroast]

yes it is trivial - at 2W, it will take 500 hours to use a whole kwh, so that is 1.2p per day which may be described as over £4 per year. but still there is far easier ways to economise

 

[JohnW2]

yes it is trivial - at 2W, it will take 500 hours to use a whole kwh, so that is 1.2p per day which may be described as over £4 per year. but still there is far easier ways to economise

Of course.

The problem is that different people view these things in different (not necessarily rational)ways, a situation which is not helped by the fact that proverbs often come in contradictory 'pairs' ....

"Pound-wise, penny foolish"
"Look after the pennies and the pounds will look after themselves"

There is also a historical issue. There was a time, before some 'regulation' came along, when quite a lot of items found in homes consumed obscene amounts of electricity when in 'standby' mode - so the issue may not have been so trivial back then, but some people's thinking has not moved forwards.