This post was based on faulty data. The test was rerun and the results are thus:
pride geoth before a fall
It's been opined by an old kid on the block that leaving a Prosumer HX Espresso Machine ON does not save energy compared to turning it off for short intervals. See Should an HX espresso machine be turned on/off
For your entertainment and elucidation, we present Home Barista's Prosumer HX Energy Analysis as applies to a Vibiemme Domobar Super HX with temperature control via pStat set at 1.1bar.another_jim wrote:This is flat out wrong, a violation of the 1st law of thermodynamics.
So if leaving it on all the time uses less energy than turning it off, the box would be storing energy that came from nowhere. I know E61 machines are pretty amazing, but they don't do perpetual motion.
A heated environment requires heat in proportion to how much hotter it is than its environment on average. If it is off some of the time, it is cooler on average than if it is on all the time, therefore it needs less heat and uses less energy, startups included.
NOTE : Your mileage may vary.
Over a twelve hour period, the machine is on for 3 hours, off for 2, on for 2, off for 2 and on until off for the day.
At idle, when fully heated the pstat cycles on for 10 seconds and off for 140, or 1:15 or 6.7%. 150 seconds is 2:30, so the usage is divided into 2:30 segments.
When the machine is cold, the heater is on 100%, for a heat input of 1 for that period. It takes about 12:30 until the first clack of the pstat. Over the next 47:30 the duty cycle gradually decreases from 25% to 6.7%. Total heat input is 8.04 units. Each interval after accumulates another 0.067 heat units to make up for the heat radiated by the machine.
The grape line is the energy in the machine. It increases until idle and then flat lines.
The red line is the total energy input to the machine while on.
The green line is the total energy input to the machine if left on.
EDIT : Images plotted on invalid data and removed by OP
As even a Chicago Democrat can see, by the end of the day more energy is input turning the machine off for a couple of hours than if left to idle.
Which brings up the obvious 'but the machine won't cool that much.' OK, to what level can the machine cool for a zero sum game?
The heat loss needs to be less than 1.7% or 25% of the typical loss. Just for grins, the dotted green line shows the cooling of an insulated boiler.
Originally stated was there's not much saving turning off for less than 5 hours, so here's the energy graph with a 5 hour off interval.
BTW, this measured data. Not pie in the sky economic theory. YMMV