[Disco_dave1]

Hi

Can somone please settle an aruguement between me and mum.

I need to know the difference (in cost, approx), between boiling a half kettle of water and 3hrs on a PC (which is then shut down, but not switched off at the mains), and the cost of leaving a SKY box on Standby 24/7

iirc, we were told at school, its more or less the same, and that it does no harm leaving the PC on as such? Can someone please clarify.

[clockworks]

I reckon that the kettle will be cheaper than the other 2.

250 watt PC on for 3 hours = 0.75 KWH
2500 watt kettle on for 3 minutes =0.125 KWH
Sky box - depends whether it's a basic or "+". From 0.25 to 0.75 KWH

If you leave the PC switched on at the wall, but shut down, for the rest of the day, it'll use another 0.84KWH or so.
Makes sense to turn off your PC (and mobile phone chargers, etc.) at the wall when they aren't being used.

Electricity costs around 14p per KWH, so your PC is costing 20p a day, the Sky box 5-10p a day, the kettle less than 2p to boil.

[Steven]

If you want to further inform your mother, vampire devices will still use electricity when plugged into the wall and switched off

GOOD 008 - Transparency - Vampire Energy



There are surge protectors you can buy which cut off vampire power

[wormvortex]

250W for a PC PSU is incredibly low by today's standards.

[fortean]

This prompted me to take some measurements that I had been meaning to do for a while...

HP Media Centre PC in use = 110W
Shutdown but still connected = 2W

Boil half a kettle of water = 100W

Sky HD box on standby = 20W

So your PC use approx. 330W + 42W = 372W per day
Boiling 4 half full kettles of water = 400W
Sky HD = 480W

So they are all quite close unless you only brew up once a day

The power rating on a PC's PSU indicates the maximum power output, not the consumption. The more cards/drives etc. you have in the more power it uses.

[neilneil]

Originally Posted by fortean

This prompted me to take some measurements that I had been meaning to do for a while...

HP Media Centre PC in use = 110W
Shutdown but still connected = 2W

Boil half a kettle of water = 100W

Sky HD box on standby = 20W

So your PC use approx. 330W + 42W = 372W per day
Boiling 4 half full kettles of water = 400W
Sky HD = 480W

So they are all quite close unless you only brew up once a day

The power rating on a PC's PSU indicates the maximum power output, not the consumption. The more cards/drives etc. you have in the more power it uses.

How did you take these measurements?
Most kettles are about 2500 - 3000watts.
Power that is drawn is measured in watts (W) or kilowatts (Kw)
The measurement of energy consumed in performing a task must include an element of time. Eg Killowatt hours.
The kettle draws a very high wattage but it is only on for say 3minutes. However something which consumes a tenth of the power only has to be on continuously for 30minutes to consume the same energy. as a 3minute boil.

-Neil

[fortean]

Originally Posted by neilneil

How did you take these measurements?
Most kettles are about 2500 - 3000watts.
Power that is drawn is measured in watts (W) or kilowatts (Kw)
The measurement of energy consumed in performing a task must include an element of time. Eg Killowatt hours.
The kettle draws a very high wattage but it is only on for say 3minutes. However something which consumes a tenth of the power only has to be on continuously for 30minutes to consume the same energy. as a 3minute boil.

-Neil

I used a device that measures the power consumption of a connected, in-line, appliance. I could also have timed how long it took to boil...

3KW Kettle = 0.833W per second
2 minutes = 120 seconds
120 x 0.833 = 99.96W

Very simple really. I'm surprised you asked the question since you practically provided the answer yourself.

A lower power kettle would take longer to boil the same amount of water but would be using less power per second.

Of course there is the unknown of how much water in half a kettle but then that's how people think of it. Nobody boils 750ml of water to brew up; they boil half a kettle of water, or a quarter, or just a bit

[richard plumb]

that sky box is surprising. How much does it use when not in standby?

My mac mini (old one) is only supposed to use 23W when idle, and thats a fully fledged computer.

For the PC, idle load should be lower than when its actively doing something

[fortean]

Originally Posted by richard plumb

that sky box is surprising. How much does it use when not in standby?

My mac mini (old one) is only supposed to use 23W when idle, and thats a fully fledged computer.

For the PC, idle load should be lower than when its actively doing something

Sky-HD in use = 34W

Have a mess with this from one of my sites...
Energy Use Calculator
...click the link on the page to open the calaculator in a pop-up window.

[Miyazaki]

Originally Posted by wormvortex

250W for a PC PSU is incredibly low by today's standards.

I think the 250W means maximum load, I don't think a 250W PSU will draw 250W all the time.

[Synchro]

Interested in this thread. Anyone got any Power usage stats from their home? I'd like a way of recorded my homes power usage, part from taking messurements from the meter by hand every now again, is there a devise that can be fitted to the meter box that can record some usage levels?

[Synchro]

Originally Posted by Miyazaki

I think the 250W means maximum load, I don't think a 250W PSU will draw 250W all the time.

Good because I have a 1000W PC PSU ;-)

[clockworks]

Originally Posted by Synchro

Interested in this thread. Anyone got any Power usage stats from their home? I'd like a way of recorded my homes power usage, part from taking messurements from the meter by hand every now again, is there a devise that can be fitted to the meter box that can record some usage levels?

Owl Energy Monitor, around £30

Remote unit clips to live cable going into meter, base unit displays instant consumption, cumulative consumption, price, etc.
Excellent device, picked one up at my local Tesco Extra a couple of weeks ago.

[Synchro]

Originally Posted by clockworks

Owl Energy Monitor, around £30

Remote unit clips to live cable going into meter, base unit displays instant consumption, cumulative consumption, price, etc.
Excellent device, picked one up at my local Tesco Extra a couple of weeks ago.

Looking for something that can send data to a PC, is this sort of thing available?

[Synchro]

Originally Posted by Synchro

Looking for something that can send data to a PC, is this sort of thing available?

After a little searching I found one. Anyone using anything like this?

Wattson energy monitor from DIY Kyoto - New LOW Price

[johnscarlet]

Originally Posted by Synchro

After a little searching I found one. Anyone using anything like this?

Wattson energy monitor from DIY Kyoto - New LOW Price

There is someone here that defo has one running , can't remember who thoigh off the top of my head . They were recently looking for a second one in the classifieds though , try a search for wattson

[Synchro]

Found it

[richard plumb]

do these monitors all handle the current 'dual tariff' bills now that we pay no standing charge (well, we do, its just rolled into the first units you use)

eco-eye also do a 'wi-eye' which plugs into a computer and lets you monitor consumption.

I'd prefer to be able to track usage over time than just have instantaneous readings.

edit: The efergy site also says they have an 'efergy2' coming soon that will support USB downloads to PC/Mac.

[richard plumb]

The wattson looks lovely, and the Mac connectivity is very useful. But it seems a bit limited in what it can do standalone. Does anyone have one and can give some impressions?

Sounds like it can only give instantaneous power usage, and cost - again at that moment. It stores the data for connecting to a computer, but you can't see it unless you do.

Some of the others give you daily/weekly/monthly power and cost and perhaps that would be more useful - and you can always put weekly/monthly costs into a spreadsheet manually..

[neilneil]

Originally Posted by fortean

I used a device that measures the power consumption of a connected, in-line, appliance. I could also have timed how long it took to boil...

3KW Kettle = 0.833W per second
2 minutes = 120 seconds
120 x 0.833 = 99.96W

Very simple really. I'm surprised you asked the question since you practically provided the answer yourself.

A lower power kettle would take longer to boil the same amount of water but would be using less power per second.

Of course there is the unknown of how much water in half a kettle but then that's how people think of it. Nobody boils 750ml of water to brew up; they boil half a kettle of water, or a quarter, or just a bit

I'm not claiming to be an expert but as I understand it Watts is a measure of the rate at which energy is being used (Joules per second). I don't think you can say a kettle took 100watts to boil half a cup of water.

I think this link might explain it better than I can.
Watt - Wikipedia, the free encyclopedia

-Neil