gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
111211-1442 EST
I am looking for one or more persons that have a Kill-A-Watt EZ (model 4460), a moderately new upright freezer of about 20 cu-ft, operating at about 0 deg F internal and 70 deg F ambient, and know what was the Energy-Star kWh per year rating on the yellow tag on the freezer.
If you fall in this category I would appreciate having you run an experiment to see what is the actual consumption. A non-EZ is probably not adequate for the experiment because it looses data on small power interruptions.
Freezers and refrigerators have a long cycle on-to-off-to-on, like 1 to 2 hours. The test needs to be done over maybe several days to a week when nothing new is added to the freezer. A few door openings and removal of contents won't have much effect on energy consumption. Putting new room temperature stuff in the freezer has a noticeable effect, already frozen stuff no problem.
The time to run the test is determined by desired accuracy and how well data measurements can be synchronized with the compressor start time. Ideally one wants to measure energy input from one start time to an Nth start time. This provides an equal number of on and off periods for the test time.
Suppose the test is run over a 1 day time period and the freezer has a total on-off cycle of 2 hours and the duty cycle is 50%, then a maximum error of 1/24 in time might occur leading to an error of 24/23 - 1 = 4.3% in the calculated average power consumed. Four days reduces this error to about 1% and averages other variables.
See:
http://www.consumersunion.org/pdf/DOE-comments-1-15-10.pdf
.
I am looking for one or more persons that have a Kill-A-Watt EZ (model 4460), a moderately new upright freezer of about 20 cu-ft, operating at about 0 deg F internal and 70 deg F ambient, and know what was the Energy-Star kWh per year rating on the yellow tag on the freezer.
If you fall in this category I would appreciate having you run an experiment to see what is the actual consumption. A non-EZ is probably not adequate for the experiment because it looses data on small power interruptions.
Freezers and refrigerators have a long cycle on-to-off-to-on, like 1 to 2 hours. The test needs to be done over maybe several days to a week when nothing new is added to the freezer. A few door openings and removal of contents won't have much effect on energy consumption. Putting new room temperature stuff in the freezer has a noticeable effect, already frozen stuff no problem.
The time to run the test is determined by desired accuracy and how well data measurements can be synchronized with the compressor start time. Ideally one wants to measure energy input from one start time to an Nth start time. This provides an equal number of on and off periods for the test time.
Suppose the test is run over a 1 day time period and the freezer has a total on-off cycle of 2 hours and the duty cycle is 50%, then a maximum error of 1/24 in time might occur leading to an error of 24/23 - 1 = 4.3% in the calculated average power consumed. Four days reduces this error to about 1% and averages other variables.
See:
http://www.consumersunion.org/pdf/DOE-comments-1-15-10.pdf
.