Help with a Spring-Lever shortlist - Page 3

Recommendations for buyers and upgraders from the site's members.
erik82
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Joined: 12 years ago

#21: Post by erik82 »

espressotime wrote:0.8 kwh in a little over an hour. Leaving it on for say 6 hours will be more than three times 12 minutes with the Export.
Export is 800 watts. So 0.8 kwh. Takes 8 minutes to warm up.That's 0.23 kwh for three times a day.

So now the big question what the Lambro consumes during an hour idle which is probably around 0.2kW (looking at the numbers others on HB have came up with in the past). And if that's the case it's still more energy efficient to leave it on for 7 hours a day (0.8kW + 6* 0.2kW = 2kW) instead of consuming 3 * 0.8kW a day (3 * 0.8kW = 2.4kW) :wink: . And you'll save a lot on maintenace also because parts don't like warming up and cooling down a lot so win-win.

espressotime
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#22: Post by espressotime »

erik82 wrote: So now the big question what the Lambro comsumes during an hour idle which is probably around 0.2kW (looking at the numbers others on HB have came up with in the past). And if that's the case it's much more energy efficient to leave it on for 7 hours a day instead of comsuming 3 * 0.8kW a day :wink: . And you'll save a lot on maintenace also because parts don't like warming up and cooling down a lot.
We are comparing leaving a big machine like a Lambro on for 6 hours to firing up a small machine like my Export every time you want a shot of espresso.
Leaving a big machine like a Lambro idle for 6 or 7 hours for three times espresso during the day doesn't feel right to me.
I never do it.
It gets fired up at 2 pm and shut off at 4.30 pm.
If I want an after dinner espresso I'll fire up the Export.

erik82
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#23: Post by erik82 »

No we where comparng leaving a machine on for a prolonged period of time versus turning it on 3 times a day for an hour. Now you're comparing apples to oranges and that test didn 't need to be done as it's really obvious that this would have been the outcome.

espressotime
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#24: Post by espressotime »

erik82 wrote:No we where comparng leaving a machine on for a prolonged period of time versus turning it on 3 times a day for an hour.
Maybe you were but not me.
Probably a misunderstanding somewhere down the line.

erik82
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#25: Post by erik82 »

Then please let us know what the Lambro consumes in an hour idle. You'll see that it may not feel right but the numbers will give you a totally different answer.

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Jeff
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#26: Post by Jeff »

To try to get this back on track, here's a couple ways to think about power consumption that may make a bit of sense about why turning the machine on and off requires less power than leaving it on.

Every day, the machine gets heated to operating temperature from cold once, consuming some amount of energy. Every day, the machine cools from operating temperature to cold once, with the power off. At the end of the day there is no additional energy retained in the system compared to when it was about to be started in the morning.

Those are constants, no matter how many times during the day it gets turned on and off.

The rate of heat loss by the system is roughly proportional to the temperature difference to ambient. The condition that it is at operating temperature when you turn it off for the last time during the day means that you have replenished the energy lost during the day. The energy lost during the day is proportional the area under the time-temperature curve. The shorter the periods of elevated temperature, the less energy is consumed.

Another way to think about it is to consider two sessions. Rather than have them being an hour apart, let them be a day apart, then a week apart, then a month. Intuitively (and provably) turning on the machine for a month solid seems as though it would consume a lot more energy than just turning it on a couple of times for a relatively short period of time.

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baldheadracing
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#27: Post by baldheadracing »

erik82 wrote: So now the big question what the Lambro consumes during an hour idle which is probably around 0.2kW (looking at the numbers others on HB have came up with in the past). And if that's the case it's still more energy efficient to leave it on for 7 hours a day (0.8kW + 6* 0.2kW = 2kW) instead of consuming 3 * 0.8kW a day (3 * 0.8kW = 2.4kW) :wink: . And you'll save a lot on maintenace also because parts don't like warming up and cooling down a lot so win-win.
You are not accounting for the fact that turning on a warm machine consumes much less power than turning on a machine that has been off overnight.

Turning off a machine must always consume less power than keeping it on, as DaveC stated. If you want to argue that peoples' interpretations of the laws of thermodynamics are wrong and yours is right, then I would suggest that a coffee forum is not the place.

The less maintenance point is very machine-dependent. The most common failure point on machines made in this century is electronics, and keeping some machines on will increase average temperature around those electronics, leading to higher failure rates of those electronics. On the other hand, something like a sight glass - a common failure point in machines that have them - does not appreciate cycling and that component would be most reliable if the machine is kept on 24/7. Another example, a vacuum breaker also does not appreciate cycling, and if the machine has the older style of vacuum breakers that spew steam pretty much every time the machine is turned on, then machine reliability will definitely suffer. (It is perhaps best to switch to a newer design of vacuum breaker.) OTOH, constant heat can bake (especially) steam wand and water valve seals.

I do keep a machine on if I'm making another espresso within a couple hours in machines with larger boilers (3l+), but I am willing to trade convenience for the small increase in cost.
-"Good quality brings happiness as you use it" - Nobuho Miya, Kamasada

erik82
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#28: Post by erik82 »

I don't understand why it's so hard to read and make completely wrong conclusions of someone else's post. Ofcourse a machine that's on 24/7 will consume more then turning it on for 3 times an hour a day but that's not what I wrote. Even a 7 year old child will get that. I was comparing leaving it on for 6-7 hours a day compared to turning it on for 3 times an hour which is something completely different but somehow you and DaveC totally ingnored that and made wrong conclusions. And in fact then you are ignoring the laws of thermodynamics by saying a cold machine will consume as much in an hour as a warm machine :wink: .

And after 3 hours a machine is maybe somewhat warm but is nearing a full cold start unlike powering it up again after 1 hour but yeah it'll consume somewhat less which is obvious. But still power usages in both use cases will be comparable.

There's a lot written about this in the past on HB and I've done some measurements myself. Unlike DaveC just posting a oneliner I did took the time to write down the math. So just calling someone stupid on results that have been tested and verrified before and not taking any effort in explaining why was just arrogant. That's my main point.

But if you want to bash someone who has done the math and has looked up the numbers versus someone who only posts a oneliner then be my guest but AFAIK that's not how we gather proper information.

espressotime
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#29: Post by espressotime »

erik82 wrote:Then please let us know what the Lambro consumes in an hour idle. You'll see that it may not feel right but the numbers will give you a totally different answer.
This has been a misunderstanding from the beginning.
I know that an espressomachine heating element is on the entire time till the set pressostat number is reached and then switches off until the bottom of the set presso interval is reached. :wink:
I'm into espressomachines for over 30 years. :D

espressotime
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#30: Post by espressotime »

Jeff wrote:To try to get this back on track, here's a couple ways to think about power consumption that may make a bit of sense about why turning the machine on and off requires less power than leaving it on.

Every day, the machine gets heated to operating temperature from cold once, consuming some amount of energy. Every day, the machine cools from operating temperature to cold once, with the power off. At the end of the day there is no additional energy retained in the system compared to when it was about to be started in the morning.

Those are constants, no matter how many times during the day it gets turned on and off.

The rate of heat loss by the system is roughly proportional to the temperature difference to ambient. The condition that it is at operating temperature when you turn it off for the last time during the day means that you have replenished the energy lost during the day. The energy lost during the day is proportional the area under the time-temperature curve. The shorter the periods of elevated temperature, the less energy is consumed.

Another way to think about it is to consider two sessions. Rather than have them being an hour apart, let them be a day apart, then a week apart, then a month. Intuitively (and provably) turning on the machine for a month solid seems as though it would consume a lot more energy than just turning it on a couple of times for a relatively short period of time.
Spot on .
My Lambi takes 45 minutes in the morning.
If I switch it on 2-3 hours later that time will be 15-20 minutes.That big lump off brass at the front stores a lot of energy.