March 20, 2024 | Medi-Products

How Many Watts Does a Medical Refrigerator Use?

Often refrigerators can be one of the highest appliances in power consumption, especially if it is an older model. If you are looking to reduce power usage, or size a battery backup for a refrigerator, you will need to find out how many watts the refrigerator uses over time. There are multiple methods you can use to do so:

What Are Refrigerator Watts?

Refrigerator watts are the amount of electrical current it’s compressor uses to cool it’s compartment. Running wattage for most household refrigerators, is usually between 350 to 750 if the voltage is 120. However, the average wattage will usually only be between 100 to 300 watts, because the compressor only runs about 30% of the time. 

Method #1 - Using the Energy Star Rating to Find the Average Running Wattage:

The easiest method is to google your refrigerators model number and see if it has an Energy Star Rating. If it does, the estimated yearly electricity usage is usually provided. A typical Energy Star Label may look like this:
energy star label explanation

Example Using the Above Label:

Energy consumption: 227 kWh per year - (that is 227,000 Watts hours per year)
If you take 227,000 and divide it by the number of days in a year (365) that will give you 621.91 watt hours per day: ( 227,000 / 365 = 621.91 wh ).
If you divide 621.91 watt hours by the number of hours in a day (24) you get 25.91 average running watts: ( 621.91 / 24 = 25.91 ).

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Method #2 - Buy an Energy Meter to Measure Power Consumption:

If your refrigerator does not have energy star rating (most vaccine and commercial refrigerators do not), you will either have to contact the manufacturer of the refrigerator (who may have this information) or purchase a KWH meter. An energy meter is a great easy way to measure your appliances power consumption, and will also be the most accurate form of measurement.
The meter you purchase will likely come with user instructions, but they are generally very easy to use. These device works by plugging the meter into the wall outlet and then plugging the refrigerator into the meter. The meter will calculate the amount of power the device is using over time.
These meters are generally inexpensive and may actually save you money on your electric bill, by helping you become more aware of how much power your appliances are using. Here are a few sellers you may be able to purchase one from:

Method #3 - Do a Calculation Using the Nameplate Amperage:

Yet another method, is to try doing a calculation using the nameplate amperage . When using a calculation based on the refrigerator nameplate amperage rating, the result is more or less an educated guess, based on an estimated duty cycle.

Calculating the Running Wattage

To find the running wattage, you will multiply the nameplate amperage x 120 (most household appliances run on 120 volts).
For instance: if the nameplate amperage is 4 amps, you will multiply it by 120 which will give you 480 running watts.

What Is A Duty Cycle?

A refrigerator compressor does not run all the time. Instead, it cycles on and off. The percentage of time the compressor is running, is called the duty cycle. The running wattage is the amount of watts the appliance uses when the refrigerator’s compressor is running, but due to the duty cycle, the average wattage will be much lower than the running wattage.

Calculating the Average Wattage

Each refrigerator has different efficiency levels, which will vary with the insulation value in the refrigerator. Typically a refrigerator runs on 35% duty cycle, (65% for a freezer). This means that if you take the running watts and multiply it by 35%, you can get an idea as to how much power the average running amps will be.
For instance: if the running wattage is 480 watts, and the duty cycle is 35%, the average wattage will be 168 watts.

Further Considerations:

As mentioned earlier, newer appliances are much more efficient than older ones. If your appliance is more than 15 years old, you will probably find that purchasing a newer model will pay it's self off within a few years due to energy savings alone, not to mention the cost of repairs which can be expected as well.
If purchasing a new appliance is not an option, another way to reduce the power consumption of your refrigerator is to keep up with the recommended maintenance. Simple tasks such as cleaning the coils and checking the seals, can lead to significant energy savings.

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