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S1
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In the analysis below, I used a Fluke multi-meter with a current probe to
capture the current in all possible operational states. Since the voltage drop
in the line varies with current I also recorded the voltage of each measured
state. The error column is a "fudge factor" I used to account for the error in
the current probe. Feel free to select a different value. Then multiplying these
three cells together yields the watts consumed by each operational state.
My latest electric bill shows 8.3 cents per kw-hr. I multiplied the kw by
this value times 24 to get the cost per day if that function where to run
non-stop.
The final step in the analysis is to determine the duty cycle for each mode to
obtain the actual cost per day for each function. I used a stop watch to measure
a few cycles while the machine was not being used to pull shots and calculated
the duty cycle. I figure I don't actually pull shots for more than 5 minutes per
day. If the machine is running the pump and both boilers for this entire time
(doubtful) that adds only 0.35% duty cycle for that mode. For normal home use,
the standard cycling of the boilers while idle swamps out the cost of the extra
power required to pull shots because it is such a small fraction of the total
duty cycle.
Feel free to download the Excel file using the link beneath the spreadsheet.
You can modify the electric cost per kw-hr to match your price and validate your
own duty cycle. Before the new quiet motor mounts were introduced, I placed
insulation on my side and rear panels. To keep the cups nice and hot I lay a
dish towel over the top of the warming tray. I am sure that this will keep my S1
in the idle state somewhat longer than other S1s. Not sure how much.
|
S1 Functions |
Amps |
Volts |
Error |
Watts |
$/kw-hr |
per 24 hrs |
Duty Cycle |
Actual/day |
|
Idle |
0.12 |
118.1 |
1.12 |
16 |
0.083 |
$0.03 |
89.42% |
$0.03 |
|
Steam Boiler & Cooling Fan |
8.44 |
115.0 |
1.12 |
1087 |
0.083 |
$2.17 |
3.41% |
$0.07 |
|
Group Boiler |
6.22 |
115.5 |
1.12 |
805 |
0.083 |
$1.60 |
2.27% |
$0.04 |
|
Both boilers, no pump |
14.64 |
115.4 |
1.12 |
1892 |
0.083 |
$3.77 |
4.55% |
$0.17 |
|
Both boilers & pump on |
16.67 |
113.1 |
1.12 |
2112 |
0.083 |
$4.21 |
0.35% |
$0.01 |
|
Group boiler & pump on |
8.28 |
115.2 |
1.12 |
1068 |
0.083 |
$2.13 |
0.00% |
$0.00 |
|
Only pump running |
2.03 |
117.5 |
1.12 |
267 |
0.083 |
$0.53 |
0.00% |
$0.00 |
|
|
|
|
|
|
|
|
100.00% |
|
|
Note: 1.12 Error = +12% fudge factor to account for possible margin of
error in current probe. This should be a very liberal value. Change it
if you wish. |
|
Daily Cost |
$0.30 |
|
|
Month cost |
$9.02 |
|
|
Annual cost |
$108.22 |
Download Excel Spreadsheet
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