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Permalink Reply by Stuart Mac on January 24, 2018 at 3:31pm

Should be fairly simple to calculate,   every piece of equipment has a tag with watts or amps,  big thing will be Air con on a commercial space that will eat up the power bill.   Second largest thing is obviously the espresso machine.

Most commercial espresso machines run around 20 amp which is 4800w,  unless you have a monster like a big linea then your up in the 50a range,  but for this argument we will stick with 20a

20A *240v = 4800W * 8 HOURS A DAY = 38400w a day * 30 days a month (you never close)

=1152000 watts,  (seams like a lot right)  your power is measured in KW so we /1000

1152000/1000 = 1152 KW/h *cents/kwh or kw hours which is what your power is measured in.  

if your power rate was 15cents per kw/h (thats pretty high)  your espresso machine would use 172.80$ a month if you shut the machine off when you close.

that math works for every piece of equipment your currently own or are looking to buy. 

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Permalink Reply by Briana Friday on January 25, 2018 at 8:56pm

Stuart, Thanks for your response. Using the method you described above is exactly what led me to create this post.

The power rates for my area are in the range of 29¢ to 34¢ per kWh (Hawaii paradise tax). With a 7,300W machine running for 10 Hours, I am up in the $650 range (if I shut the machine off). 

However, I am under the impression that, for many machines, the energy required for the machine to fully warm up in the morning is comparable to the energy required to stay warm over night.

So, when I did the calculation the first time, I figured 7,300 watts x 24 hours etc. etc. This gave me approximately $1500/Month. Both $700 and $1500 per month seem high to me, but if thats the cost, thats the cost.

But, I am not comfortable with that much potential for variance in energy costs for one piece of equipment (albeit the main piece of equipment). With the energy costs that I am subject to, I would like to get closer than that.

Also, I always thought that this formula doesn't necessarily give me a complete picture (A fridge is only pulling power when the compressor is on, and the compressor may only run 9 hours in a day). If that is correct, I am not aware of comparable info for commercial espresso machines. 

What I would like to better understand is how much/often are my machines and equipment at full power consumption, partial consumption, minimal consumption etc.

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Permalink Reply by Stuart Mac on January 27, 2018 at 4:25pm

Depends what the machine is,  and if the boiler is insulated,  what the ambient temp is ect.    In most cases people leave the machines on 24/7 but i believe that the 15-20 min warm up time would be no less costly than an extra 8-10 hours of idle time.   

Some machines use a pressure switch and the entire element is on or off,  so full power or no power.

Some are solid state and vary the number of elements running at any given time and pulse the power to the elements to maintain a very even temperature with less variation than a mechanical switch.    In theory the solid state system saves you energy by pulsing the elements as the metal stays warm between power pulses and continues to heat the water.

Un-fortunately there is no way to calculate the demand load of the machine aka how many drinks your going to make ect,   so you cant really quantify a number for number of hours a day that the element is engaged vs machine at idle.  

if yours is 7300w,  its only going to use that when your pulling shots and steaming at the same time,  full load,  as soon as you stop its going to recover and turn itself down or off depending on the control.   You need this idle power value to further work your formula for a better number.  

A commercial fridge has an evap fan that runs 24/7 so even when the unit is not cooling its not off,  same as the espresso machine,  most have a large power supply and digital controls that are going to use some amount of power all the time thats your idle value. 

The only real way to know is get a data logger that can record kwh and run it on your machine for a few days.   You could also do some experiments of off at night vs running for two days straight.  

By the way those power rates are nuts,  you should move you shop outside and just get a gas machines or a massive grid tie solar setup.

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