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Thread: Leaving an HX machine on.

  1. #1
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    Leaving an HX machine on.

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Ive been meaning to do some calcs on how long the heating element in my boiler would in a day either leaving it on most of the day or turning it on every time I want to make a coffee. Here are my calcs and assumptions. Let me know what you all think.


    A typical day on my machine would be to do three separate lots of coffee between 8am and 9pm. I turned my machine on when I got home for work. The first 480 seconds (8 minutes) the element was on. After that it went into the 10 seconds every 120 seconds. The machine would be on another 3000 seconds (50 min). In that 3000 seconds the element would be on 250 seconds giving a total of 730 seconds every time I switch the machine on for a coffee or 2190 seconds for the day(36.5minutes)

    If I switched the machine on at 8 in the morning it would use 480seconds to heat the boiler. The element would be on for another 3860 seconds until I turn it off at night giving a grand total of 4340.

    This means that in theory the life of the element would be halved. by the same token it is also possible that the stress put on the element heating the boiler up because it is running constant for 8 minutes is greater than when it is cycling. Kinda like a car, the engine wont last long at maximum for long.


  2. #2
    Senior Member Dennis's Avatar
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    Re: Leaving an HX machine on.


    Quote Originally Posted by 46797F786562534E637560690C0 link=1247480525/0#0 date=1247480525
    Let me know what you all think.
    I think you have too much time on your hands...I had a laugh...had to be said. ;D


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    Re: Leaving an HX machine on.

    Its an interesting question that I have thought about too. Have read that for a commercial size machine its better to leave on as it is under stress when first turned on to bring it up to pressure (and you need to serve customers of course) - opposite for a single boiler that has a small capacity which probably leaves the HX somewhere in the middle - anyone have a theory on whether best to leave on all day or switch on/off as needed?

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    Mal Dimal's Avatar
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    Re: Leaving an HX machine on.

    This topic has been discussed ad nauseum over the years, and quite recently too.

    A search of the forum will turn up a heap of info...

    Mal.

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    Re: Leaving an HX machine on.

    I thought that the last time it was discussed wasnt on the merits of stressing the machine rather whether or not it would help stop corrosion etc thats why I posted.

    PS dennis too much time on my hand as apposed to what? Someone spending hours learning the art of temp surfing on their dual purpose boiler machine or someone spending the day trying different roast profiles on a new bean. Its what we do isnt it? I simply checked the above to get an idea of whether it is worth leaving my machine on all day or planning when I want a coffee and turning it on then.

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    Re: Leaving an HX machine on.

    Quote Originally Posted by 17282E293433021F322431385D0 link=1247480525/4#4 date=1247499092
    PS dennis too much time on my hand as apposed to what?
    It was a play on words. *Peruse Barista Venting for more of Dens quick-witted repartee. *Im sure 90% of the customers dont get it....which makes it all the more hilarious *;D

    If I recall previous threads correctly, a generic HX thats left idle for >4hrs uses more electricity than one thats turned off then back on. *Your usage, machine type and cost of electricity will dictate what variation of that equation you fit into.

    As for stresses, the first passengers of the De Havilland Comet quickly learnt about metal fatigue in a repeatedly pressurised metal tube. *The lack of windows down the side of your boiler is of some help but the stresses are still there * :D

    So whats the right thing to do? *NFI. *If we lock a Sparky, a materials ginger beer & a thermodynamicst in a room with enough coffee, they may come up with an answer. *But till then, Ill be continuing to run off a timer from 7 to 12 in the mornings and flick the switch on arrival in the afternoon.

  7. #7
    Senior Member redzone121's Avatar
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    Re: Leaving an HX machine on.

    Hi Justin
    Yep its had a fair airing alright and of course all interesting. The last thread i followed on the subject was about the cost of running. Anyway I am now turning on and off 2-3 times per day, certainly time wise it is far quicker on second heating than initial heat up. Saturdays on all day when family home. Wear and tear I think the jury is still out, pros and cons like anything I guess. Keep the research and stats going mate its people like you that keep this forum so interesting.

    Chris

  8. #8
    Senior Member Dennis's Avatar
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    Re: Leaving an HX machine on.

    Quote Originally Posted by 447B7D7A6760514C6177626B0E0 link=1247480525/4#4 date=1247499092
    PS dennis too much time on my hand as apposed to what?
    No offense meant Justin - twas light-hearted. Just had visions of you with stopwatch in hand. :)


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    Re: Leaving an HX machine on.

    I do the same as redzone on this one, purely for a cost running exercise.
    I hadnt really thought too much about the stress levels of the element as all its doing is heating and i wouldnt think an initial heat up is that much more stressfull than its normal cycle as taking water out of the boiler would start the same heating process anyway, the temperature of the rest of the machine is a function of the whole thing heating up which is why i leave the machine at least 30 mins before my first coffe when starting from cold.

    Mal

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    Re: Leaving an HX machine on.

    My understanding is that most cafes turn their machines off at night. I do that with my commercial. Pressurestat diaphragm and contacts would prefer it.
    Brett

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    Re: Leaving an HX machine on.

    Quote Originally Posted by 56474E474F4351564750220 link=1247480525/9#9 date=1247570714
    most cafes turn their machines off at night.
    I know a LM agent that tells his commercial customers to never do so.

    Like most things, ask 3 people, get 4 opinions! *:)

    (edit)

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    Re: Leaving an HX machine on.

    Hmm but my GS3 comes with a timer function.

    If its bad then they wouldnt have included it?

  13. #13
    TC
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    Re: Leaving an HX machine on.

    Quote Originally Posted by 2503140B0C53620 link=1247480525/11#11 date=1247574301
    Hmm but my GS3 comes with a timer function.

    If its bad then they wouldnt have included it?
    I doubt that many cafes owners necessarily want to arrive at least an hour before their customers to switch on ther machines.

    I suspect that you will find the overwhelming majority of cafe owners leave their machines switched on 24/7

    2mcm


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    Re: Leaving an HX machine on.

    Hmm does that mean I should leave it on....

    I guess each has its own pros and cons...... timer vs 24/7

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    Re: Leaving an HX machine on.

    Quote Originally Posted by 4365726D6A35040 link=1247480525/13#13 date=1247576530
    Hmm does that mean I should leave it on....

    I guess each has its own pros and cons...... timer vs 24/7
    No need Gavin,

    You have a timer to do the job for you...

    Most cafes dont and most customers arent prepared to wait an hour for a coffee ;)

    2mcm

  16. #16
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    Re: Leaving an HX machine on.

    Quote Originally Posted by 6E485F404718290 link=1247480525/13#13 date=1247576530
    Hmm does that mean I should leave it on....
    I wouldnt have thought so Gav, unless youre a prolific user (all day, every day)

    The dont turn it off instruction related to multiple group Lineas etc from both an electical consumption perspective. *ie. machines with a huuuuuge thermal mass

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    Re: Leaving an HX machine on.

    Quote Originally Posted by 17223B316564520 link=1247480525/15#15 date=1247576890
    unless youre a prolific user (all day, every day)
    ::)


    I use the timer :D

    Oh and I read somewhere awhile back that timer use, ie turning it on and off everyday increases scale buildup?

  18. #18
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    Re: Leaving an HX machine on.

    Basically,

    With HX machines intended for the domestic user, components are mostly manufactured to a lower spec than fully fledged commercial machines and as such, not intended for 24/7 activity. The components most affected are those of an electrical/electronic nature or non-metallic. Heat is the enemy of electrical/electronic components where continuous switching, slowly but surely erodes away electrical contacts such as those found in Relays and P/stats for example. Wiring insulation will slowly but surely degrade and depending on the insulation material used, this can be measured in years not decades.

    Also, given that domestic HX machines are much more compact than dedicated commercial machines, everything contained within the much smaller case/enclosure will be raised to a higher temperature above ambient and besides, larger commercial machines allow for the more heat sensitive components to be located further away from the Boiler(s) and thereby reduce the rate of degradation.

    And there is the overall waste of energy aspect to consider. One way or another, this is something for which we all pay at some level. If you are one of those few people who literally drink coffee throughout the entire day at home (and cant wait the 30-60 minutes for the machine to warm up), then you may want to consider insulating the Boiler(s). This will have two beneficial effects, namely: a considerable reduction in the energy wasted (and used) and a much cooler environment for all those components susceptible to thermal degradation processes and fewer heating cycles reduces wear and tear on the Heating Elements and control devices. Win/win/win... 8-)

    cheers,
    Mal.



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