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Question about wattage ratings.

Discussion in 'General Discussion' started by Energize, 19 May 2006.

  1. Energize

    Caporegime

    Joined: 12 Mar 2004

    Posts: 28,753

    Location: London

    If say a shower is rated at 10.5 Kw does this means it uses 10.5Kw an hour? We're trying to work out why the electricity bill is so high.
     
  2. ricky1981

    Mobster

    Joined: 10 Jun 2003

    Posts: 4,584

    Location: New Zealand

    It means its power is 10.5kW, in an hour it would user 10.5kWh (kilowatt hours). 10.5 is quite a lot but you'd need be taking pretty long showers for it to really build up.
     
  3. Mark A

    Capodecina

    Joined: 19 May 2005

    Posts: 18,015

    Location: Lancashire

    Plus that figure is probably at its highest setting?.

    Mark
     
  4. Adam_151

    Mobster

    Joined: 18 May 2004

    Posts: 2,713

    Location: Lincoln, Uk


    That would be true, but a shower generally only has one or two power settings, the control dial that you use to set the temperature just controls the flow rate of water through the heater can (same amount of power + less water = hotter water), the dial that is on some showers that has full on, ecconomny, cold and off does adjust power taken though (it shuts off one of the heating elements in the heater can when on eccomo mode)
     
  5. Energize

    Caporegime

    Joined: 12 Mar 2004

    Posts: 28,753

    Location: London

    All it has is one dial for temperature (crap I know), I was wondering is there a chance that it uses more than 10.5kw due to it not being 100% efficent like computer power supplies do?
     
  6. singist

    Mobster

    Joined: 18 Oct 2002

    Posts: 4,446

    Location: Student Hell Headingley

    more likely it's the heating and lighting for those "plants" you're cultivating .. ;)
     
  7. Burnsy2023

    Man of Honour

    Joined: 17 Nov 2003

    Posts: 36,543

    Location: Southampton, UK

    It won't consume any more than 10.5KW. The figure is it's maximum power usage at full power.

    Burnsy
     
  8. Aod

    Sgarrista

    Joined: 7 Oct 2004

    Posts: 8,675

    Location: London

    i'm not really sure, but watt figures are usually watts per second or something? i'm sure that calculations for power involving watts and time, its measured in by the second.
     
  9. p4radox

    Capodecina

    Joined: 1 Oct 2004

    Posts: 10,767

    Location: Prague

    Watts is a measure of power - which is the rate of expenditure of energy. 1 Watt = 1 Joule per second. you pay for energy in Kilowatt hours, so if that shower was on for an hour it would cost you 10.5 KWhours.

    The shower would probably always be at the same power, the temperature is usually altered by changing the flow of the water - the faster the flow the lower the temperature of the water coming out.
     
  10. Energize

    Caporegime

    Joined: 12 Mar 2004

    Posts: 28,753

    Location: London


    Why is it different for computer power supplies then? They can be rated at 500watts but use 600 because of only being 80% efficent.
     
  11. Burnsy2023

    Man of Honour

    Joined: 17 Nov 2003

    Posts: 36,543

    Location: Southampton, UK

    Beacuse its a heating element and works on 230V~ and doesn't need any step down transformers to bring the voltage down to the needs of a pc (+-5v, +-12v etc). Which is why they are only 80% efficient as they need to charge the coils in the transformer.

    Burnsy
     
  12. Swanster

    Hitman

    Joined: 20 May 2003

    Posts: 853

    Location: Nottinghamshire

    When a shower is rated at 10.5kw, it means that's much power it needs to work. For a psu, it means how much power it is able to supply to the computer.