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Power Consumption - on all day or not?

Discussion in 'The Hummy Arms' started by oijonesey, Apr 20, 2012.

  1. oijonesey

    oijonesey Hummy.tv SEO Guru

    A question was asked in This Thread about the costs of keeping the box on all day vs Standby vs Low Power mode etc, so I thought it best to do this over here as I have a feeling my bumbling mathmatical efforts are likely to be pulled to bits so here goes (and even if I am wrong at least by the end of this I'll have the right answer!!)...

    If this is completely mis-informed rubbish please accept my apologies and I would welcome some educational feedback!!.....Here goes:

    For simplicity I'm taking standing charges out of the equation - when I got one of those monitor things from my provider they told me to average it out over the month which got me a flat 16 pence per kilowatt hour. (and apologies to the purists if I get capital and lower case initials wrong)

    So, if I had a 1 kW heater for example - leaving it on for 1 hour would be 1 kWh used and would cost me 16p (for 1 kWh). So if I left it on 24/7 it would cost me

    Per Day - 16p x 24 hours = £3.84
    Per Week - £3.84 * 7 = £26.88
    Per Month - £3.84 * 30 = £115.20 (other numbers of days per month are available ;))

    But the Hummy does not use 1kW per hour - the manual says max 28W down to <1W in standby with power saving on. I'm guessing that if the disk isn't spinning then it's probably the fan that draws the lions share of that(?) But lets assume if it's on it was using the full 28W all the time - you could think of that as 0.028 kW so for an hour it would be 0.028kWh which multiplying that by my 16p would give me just under 0.5p per hour. So IF (and I'm crossing my fingers about this) we apply that to the factors above I get just under 11p per day or £3.22 per month and therefore slightly over £38 per year total (remember that is assuming the box is using the full 28 watts all the time 24/7).

    If you switch off at night and use idle and timers to control on/offs wherever possible during the day then that figure can only get lower.

    Granted on standby at <1W you'll consume even less than that but by my reckoning the most money you could save would never be more than the £38 - and given that you will have be box on for some amount of time most days then you wont save all of that.

    OK that's my interpretation at least - I'm sure someone will be able to put a formula up that cuts through all my words and sums it up in less than 10 characters but I'm not a numbers man so I couldn't have done that I'm afraid.

    Now for the dissection (please be gentle with me)....

    [EDIT - corrected use of capitals to appease the Head Master, or is that Headmaster, or Hm or HM?]
  2. oijonesey

    oijonesey Hummy.tv SEO Guru

    Actually to try and answer mihaids original question

    Fully on would be 16p * 0.028kWh = 0.5p per hour
    standby would be 16p * 0.001kWh = erm - a very small amount of pence per hour - the calculator said 0.016p !!
  3. Ezra Pound

    Ezra Pound Well-Known Member

    As the person who was 'nit picked' against I can relate to this comment. I used KWH which I admit is incorrect, but did anyone really think it meant anything other than Kilo Watt Hours? 'K' is Kelvin, W is Watts and H is Henrys, but when talking about standby power did anybody really get confused. Kelvin Watt Henrys doesn't mean a lot. So it should be kWh but by all means use any combination of upper and lower case you like, I'm sure we'll still follow what you're saying :D
    By The Way, Not Becquerel (Bq) Testla Watts. The fan doesn't run when the Hard disk isn't spinning, The power is taken to run the clock in the display (even when the display is blank) and the Remote control receiver
  4. Black Hole

    Black Hole May contain traces of nut

    Change all the KW and KWh to kW and kWh and I'll let you off the inevitable detention.

    Write 1000 times "I must not use a capital K as an abbreviation for kilo"

    Other than that, looks OK to me at first glance. The issue is not so much one of cost as how many power stations are required to support all the HDR-FOXes being left on all the time.
  5. Black Hole

    Black Hole May contain traces of nut

    That was a bigger issue than just a lower case K, although it seems to have gone unnoticed. The main problem was your confusion between units of power (kW) and energy (kWh). The revolutions of the Watt-hour meter record cumulative energy consumption, the speed of the wheel indicates instantaneous power.

    However, as has been noted in another topic, lax use of language / notation / whatever leads to more laxness and a creeping deterioration of the educational standard. In private we all can follow what is meant, but we are not in private so let's set a good example.
  6. oijonesey

    oijonesey Hummy.tv SEO Guru

    Luckily the critique only extended to my use of capitals which I have just corrected - seems I'm not going to get a discharge for being mad after all - wibble!!]
  7. Ezra Pound

    Ezra Pound Well-Known Member

    Should that read 'There was a bigger issue ..." Oh Dear ! ! !
  8. Black Hole

    Black Hole May contain traces of nut

    If I say nothing people might think I accept your point. Think again.
  9. mihaid

    mihaid Member

    I would imagine that the hard disk always spins since the current channel is being recorded for the buffer.
  10. mihaid

    mihaid Member

  11. Ezra Pound

    Ezra Pound Well-Known Member

    There may be some confusion over the original statement in #1. In standby the hardisk doesn't spin and neither does the fan, In 'On Mode' the hard disk is always spinning reguardless of whether it is making a recording or not and the fan is on about 50/50 I would say
  12. Cancunia

    Cancunia Member

    Just found this thread after poking around for a couple of days looking for ways to leave the box on for ad-hoc remote access and save power. From what I can tell the HDR uses about 10-15Watts when fully awake with little or no playback / recording load. Using the original 16p/kWh that would put the HDR at somewhere in the region of £25-£30 per year allowing for occasional heavier usage. It's still a lot less than I seem to remember my Sky HD box uses and a lot less than my Laptop which seems to run at about 40Watts.
    Still, it would be nice to be able to keep the USB (for WLAN) or Ethernet ports active while in standby. I'll start another thread over on CF to see if there are any ideas.
  13. Ezra Pound

    Ezra Pound Well-Known Member

    Something else to be considered is that in 'normal' use the Humax could be on maybe 6 Hours a day, so to keep it on full time is would only be adding 18 hours a day of 'on-time' . It could be as little as £14-£21 for 24 Hours or £10-£16 for 18 Hours . As far as keeping USB and LAN connectors active in stand-by goes, I think It's very unlikely to be possible due to the way the hardware is designed, you can't supply power to them without powering everything else
  14. socrates

    socrates Member

    I'm a bit late to this one but for what it's worth....... my HDR replaced an original TIVO from about 2001. That didn't have a standby mode, it just ran all the time buffering live TV for 24 hours a day, 365 ( and a bit ) days a year for 11 years or so apart from a brief rest for repairs following a lightning strike. It consumed about 40 watts an hour plus in latter years an extra couple for the separate digibox it controlled post switchover. Can't say I've noticed a big reduction in my leccy bill.

    I've considered running the HDR in the same way but given the availability of scheduled wake ups and remote scheduling I haven't found a need yet.

    BTW given that your standing charges are covered in the first 'n' units per period if you are considering the marginal cost of running the HDR 24/7 you should just use your lower rate charges ( unless you are already incredibly frugal ).
  15. prpr

    prpr Well-Known Member

    No, it consumed about 40 watts. Power is energy per unit time. It is nonsense to talk of power per unit time - it's meaningless.
  16. socrates

    socrates Member

    Indeed - it's good to be reminded watts watt. Or should that be which?
  17. Black Hole

    Black Hole May contain traces of nut

    It could read "40 watt-hours per hour" (or 0.04 kWh/h)
  18. socrates

    socrates Member

    It could - accelerating consumption seems apt with all the new gizmos.

    Was it Rumsfeld who said " I don't know what I meant but I know that I meant it"?
  19. Black Hole

    Black Hole May contain traces of nut

    Since your intention was to express the consumption of energy in terms of cost, and as cost is calculated from "units" used where a unit is 1kWh, I think 0.04 kWh/h hits the mark better than the strictly accurate 40W.
  20. socrates

    socrates Member

    Thanks BH - ever the voice of sanity.