What percentage of a washing machine's energy is used purely to heat hot water?

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  • BellaBlondykeTheThird
    BellaBlondykeTheThird Posts: 286 Forumite
    First Post Name Dropper Photogenic
    edited 5 January at 9:46PM
    I can't compete with war and peace every response so will try and keep things short.

    No one on here that I can see has said urine was dirty, they did however say faeces on under garments and from crevices was.

    It does sound like you have  a regimented routine to keep bacteria to a minimum but for those that don't have that regime then the hot water wash is their friend and regular washing with keep things at bay. To put forward anything else without your obvious knowledge and routine might be considered dangerous advice?

    Anyway I'm going to listed to that Radio 4 segment tomorrow to see if I can learn something from a professional in their field not some unknown on t'internet.

    Think this is the segment

    https://www.instagram.com/reel/C1uPDhuMkXV/?igsh=dm1neGw1OTZjeHZm
  • JSHarris
    JSHarris Posts: 374 Forumite
    First Post Name Dropper
    edited 6 January at 8:59AM
    BellaBlondykeTheThird said:

    No one on here that I can see has said urine was dirty, they did however say faeces on under garments and from crevices was.

    Not so.  As long as you're not ill then there's nothing really dangerous in your faeces most of the time.  If there was then all the many millions of animals that lick their own backsides to stay clean would never survive.  Humans evolved for millennia without washing their backsides, or washing clothing or bedding come to that.  

    Cleanliness is a relatively modern, sociological, creation, stemming largely from living in very close proximity (hence being more aware of odours) that resulted from the human race moving from a scattered, low population density, agrarian lifestyle to a post-industrial one, with it's associated massive increase in population density.  It goes without saying that pathogens are very good at taking advantage of the increased opportunities for breeding from a high density host population.

    .
  • QrizB
    QrizB Posts: 13,822 Forumite
    First Post First Anniversary Photogenic Name Dropper
    That's edited highlights; the R4 spot was about 10 minutes long and went into more detail.
    N. Hampshire, he/him. Octopus Go elec & Tracker gas / Shell BB / Lyca mobi. Ripple Kirk Hill member.
    2.72kWp PV facing SSW installed Jan 2012. 11 x 247w panels, 3.6kw inverter. 30MWh generated, long-term average 2.6 Os.
    Taking a break, hope to be back eventually.
    Ofgem cap table, Ofgem cap explainer. Economy 7 cap explainer. Gas vs E7 vs peak elec heating costs.
  • Sterlingtimes
    Sterlingtimes Posts: 2,390 Forumite
    Name Dropper First Post First Anniversary
    edited 9 January at 3:16PM
    With the help from various correspondents here, I think I am close to answering my own question.

    I have recorded the times (see figure).

    The 40-degree cotton wash with 1300 RPM spin uses 690 watt-hours. The current machine is a Beko cold-fill (label is set up prospectively on the smart plug for the new Ebac machine).

    The cold water heating cycle uses 505-watt hours, heating from 9 to 40 degrees.

    Therefore, the percentage of the cycle used to heat water appears to be 505/690 x 100 = 73%.

    I take delivery of the Ebac hot fill later this week, and will then do some comparison measurements.

    Note: Y-axis shows watt hours. The X-axis shows the time of day.
    Repeat measurements will be required.








    I have osteoarthritis in my hands so I speak my messages into a microphone using Dragon. Some people make "typos" but I often make "speakos".
  • QrizB
    QrizB Posts: 13,822 Forumite
    First Post First Anniversary Photogenic Name Dropper
    The cold water heating cycle uses 505-watt hours, heating from 9 to 40 degrees.
    Interesting! That suggests that, if we ignore losses, (water + laundry + machine) has the same heat capacity as ~14 litres of water.
    I take delivery of the Ebac hot fill later this week, and will then do some comparison measurements.
    I look forward to seeing how those compare.

    N. Hampshire, he/him. Octopus Go elec & Tracker gas / Shell BB / Lyca mobi. Ripple Kirk Hill member.
    2.72kWp PV facing SSW installed Jan 2012. 11 x 247w panels, 3.6kw inverter. 30MWh generated, long-term average 2.6 Os.
    Taking a break, hope to be back eventually.
    Ofgem cap table, Ofgem cap explainer. Economy 7 cap explainer. Gas vs E7 vs peak elec heating costs.
  • DullGreyGuy
    DullGreyGuy Posts: 10,187 Forumite
    First Post First Anniversary Name Dropper
    JSHarris said:
    BellaBlondykeTheThird said:

    No one on here that I can see has said urine was dirty, they did however say faeces on under garments and from crevices was.

    Not so.  As long as you're not ill then there's nothing really dangerous in your faeces most of the time.  If there was then all the many millions of animals that lick their own backsides to stay clean would never survive.  Humans evolved for millennia without washing their backsides, or washing clothing or bedding come to that.  

    Cleanliness is a relatively modern, sociological, creation, stemming largely from living in very close proximity (hence being more aware of odours) that resulted from the human race moving from a scattered, low population density, agrarian lifestyle to a post-industrial one, with it's associated massive increase in population density.  It goes without saying that pathogens are very good at taking advantage of the increased opportunities for breeding from a high density host population.

    .
    Nor would fecal transplants exist (https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/fecal-transplant) - safe to look at from work but you probably don't want to read about it at all let alone the idea of someone else's poo being put down your throat. 

    As to the original question, which we've all become very distracted from, I am surprised that 90% of electricity consumption would come from water heating. Our dishwasher, obvious a different class of device, has a hot water intake option and the manual is fairly clear on the electricity consumption for each programme with either cold or hot water feed. The saving with it is about 40-50% on most programmes and I'd have thought there is less energy involved in just moving the water around -v- the wash machine where you have to spin the drum with a heavy load. 
  • Sterlingtimes
    Sterlingtimes Posts: 2,390 Forumite
    Name Dropper First Post First Anniversary
    QrizB said:
    The cold water heating cycle uses 505-watt hours, heating from 9 to 40 degrees.
    Interesting! That suggests that, if we ignore losses, (water + laundry + machine) has the same heat capacity as ~14 litres of water.

    That is an interesting calculation that I had not thought about. This is for the extant Beko machine.

    Ebac suggests that 20 litres of water are used in the same cycle, but drum capacity is higher. Ebac also stated this " ... the machine will take in a small amount of cold water first to ensure that the hot water does not ruin clothes. It will then use a mixture of hot and cold to reach the temperature you have set it to."

    In preparation for the Ebac tests, I have run off water from my hot tap, abient 21 degrees: first litre 24.8 degrees, pour way, second litre 31.1 degrees, pour away, third litre 36.2 degrees, pour away, fourth litre 42.8 degrees, pour away, fifth litre 47.2 degrees, pour way, sixth litre 50.2 degrees. Then constant. 
    I have osteoarthritis in my hands so I speak my messages into a microphone using Dragon. Some people make "typos" but I often make "speakos".
  • MeteredOut
    MeteredOut Posts: 1,258 Forumite
    First Post First Anniversary Name Dropper
    edited 9 January at 4:26PM
    QrizB said:
    The cold water heating cycle uses 505-watt hours, heating from 9 to 40 degrees.
    Interesting! That suggests that, if we ignore losses, (water + laundry + machine) has the same heat capacity as ~14 litres of water.

    That is an interesting calculation that I had not thought about. This is for the extant Beko machine.

    Ebac suggests that 20 litres of water are used in the same cycle, but drum capacity is higher. Ebac also stated this " ... the machine will take in a small amount of cold water first to ensure that the hot water does not ruin clothes. It will then use a mixture of hot and cold to reach the temperature you have set it to."

    In preparation for the Ebac tests, I have run off water from my hot tap, abient 21 degrees: first litre 24.8 degrees, pour way, second litre 31.1 degrees, pour away, third litre 36.2 degrees, pour away, fourth litre 42.8 degrees, pour away, fifth litre 47.2 degrees, pour way, sixth litre 50.2 degrees. Then constant. 
    Does your Beko or Ebac have load sensing to weigh the wash load? If so, you'll want to ensure the re-test with the Ebac has the same amount of load, since the amount of water used and, presumably, the amount of water it heats, will be different.
  • Sterlingtimes
    Sterlingtimes Posts: 2,390 Forumite
    Name Dropper First Post First Anniversary
    edited 9 January at 5:53PM
    Does your Beko or Ebac have load sensing to weigh the wash load? If so, you'll want to ensure the re-test with the Ebac has the same amount of load, since the amount of water used and, presumably, the amount of water it heats, will be different.
    I hadn't thought about that. I will do some checking to see if the information is available.

    P.S. Yes, the  Beko manual says that "the machine automatically adjusts the amount of water according to the weight of the loaded laundry". However, for cottons, the differential water usage in the consumption table shows little difference between 4kg (47 litres overall) and 8kg (54 litres overall). I do not know yet about the Ebac. 
    I have osteoarthritis in my hands so I speak my messages into a microphone using Dragon. Some people make "typos" but I often make "speakos".
  • MeteredOut
    MeteredOut Posts: 1,258 Forumite
    First Post First Anniversary Name Dropper
    Does your Beko or Ebac have load sensing to weigh the wash load? If so, you'll want to ensure the re-test with the Ebac has the same amount of load, since the amount of water used and, presumably, the amount of water it heats, will be different.
    I hadn't thought about that. I will do some checking to see if the information is available.

    P.S. Yes, the  Beko manual says that "the machine automatically adjusts the amount of water according to the weight of the loaded laundry". However, for cottons, the differential water usage in the consumption table shows little difference between 4kg (47 litres overall) and 8kg (54 litres overall). I do not know yet about the Ebac. 
    That's just under 15% more water.
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