Energy Efficient Refrigerators

System

Does anyone know which would be the most energy efficient refrigerator in the 18 to 20 cubic foot range?

autoxsteve

Re: Energy Efficient Refrigerators

Yes. Go here and download the Excel spreadsheet on the middle right side of the screen.

You can then sort by size and efficiency....

SolarJohn

Re: Energy Efficient Refrigerators

Amilkar wrote: »

Does anyone know which would be the most energy efficient refrigerator in the 18 to 20 cubic foot range?

I recently bought a Sears Kenmore, mostly because of the energy-star rating. Sadly though, my Kill-A-Watt meter indicates that it uses more energy than the energy-star tag says it should. I can see no reason for the discrepency. It gets plenty of side, back, and top ventillation, and the temperature in my kitchen is reasonable.

I guess these ratings are like the gasoline milage rating on cars; you never do as well as the sticker suggests.

John

System2

Re: Energy Efficient Refrigerators

SolarJohn:

That is exactly what happened to me. Now I don't know whether to trust the yellow tag or my kill a watt.

I have a very old and big side-by-side. My kill a watt reads 226 watts. I went to Sears; the salesperson let me measure a new refrig. (the yellow tag indicated a compsumption of less than half of my own), but the reading was around 180 which is not as good as I was expecting (mine is a 900 klwh per year, the one at Sears is a "407 klwh" per year, acording to the yellow tag)

crewzer

Re: Energy Efficient Refrigerators

Hmmm... I don't think that a "snapshot" view of a fridge's power comsumption will tell you much about its energy use. For example, a fridge that draws 180 W and runs for six hours/day will consume 1,080 Wh/day. A fridge that draws 226 W and runs for 9 hours/day will consume 2,034 Wh/day. 180 W is only ~20% less power than 226 W, but 1,080 Wh is 47% less energy than 2,034 Wh.

My Sears fridge appears to operating nominally when viewed from an annual energy consumption perspective. It exceeds "average" daily energy requrements in the summer, but beats the average in the winter. I'll post a Nov. 1, 2007 through Feb. 1, 2008 update on this discussion thread tomorrow morning.

John: Can you share some of your numbers with us? Thx.

HTH,
Jim / crewzer

System2

Re: Energy Efficient Refrigerators

Crewzer:

I understand your point, and I do agree. Nevertheless, my point was that at any given moment a fridge that is drawing 226 watts consumes more energy than a fridge that is drawing 180. Hence, all the other factors being equal, those percentages you mentioned should be proportional. I.e.: If, for example, 450 kwh is half 900 kwh, then if the reading from the last one (using the kill-a-watt meter) at any given moment is 226, the reading from the first one should be (in theory) around 113.

In other words: If both refrigerators run exactly the same amount of hours dayly, and the yellow tag of refrigerator "A" indicates 900 kwh per year, while refrigerator "B" tag indicates 450 kwh per year, Shouldn't the kill-a-watt reading for "B" be HALF of the reading for "A"?

Am I wrong?

Additional: The metal plaque inside of refrigerator "A" says 6.5 amp (full load), while in refrigerator "B" it reads 4.5 amp. Well, 4.5 is clearly NOT half of 6.5. How can I make sense of all those numbers?

mike95490

Re: Energy Efficient Refrigerators

Amilkar wrote: »

Nevertheless, my point was that at any given moment a fridge that is drawing 226 watts consumes more energy than a fridge that is drawing 180.

You need to consider the power drawn for a entire cooling cycle, not instantaneous usage.

Assume an Energy Star fridge runs 4 hours a day, 400 watts.

Old Bertha, with cat hair in the coils, only draws 200 watts, for 11 hours a day

The fridge with 200w draw, over a day, consumes 2200 watt hours
the E.S. fridge, because of better insulation or whatever, consumes 1600 watt hours

The instantaneous usage only counts when considering the size/capacity of your inverter, the daily usage determines battery bank/ recharging system size.

Both parts have to be considered.

The metal nameplate tags are an average. Startup surge is larger, running is less, and the defrost cycle may hit nameplate.

System2

Re: Energy Efficient Refrigerators

Mike 90045:

You mentioned three (3) different things:

"The metal nameplate tags are an average. Startup surge is larger, running is less, and the defrost cycle may hit nameplate"

"Startup surge" I know; "running", I assume, is when the motor is running and we can hear and feel the vibration. But, what is the "defrost cycle"? How long does it take?

icarus

Re: Energy Efficient Refrigerators

If my memory serves ( and it may not) the defrost cycle includes a heating element in the freezer as well as a vent fan to defrost. It adds to the energy consumption.

I know that my Propane Fridges have a heater to do the same. To save power, we just do it by hand now as needed.

Icarus

crewzer

Re: Energy Efficient Refrigerators

Amilkar,

Unfortunately, I’d say that your statement is essentially wrong.

If both refrigerators run exactly the same amount of hours dayly, and the yellow tag of refrigerator "A" indicates 900 kwh per year, while refrigerator "B" tag indicates 450 kwh per year, Shouldn't the kill-a-watt reading for "B" be HALF of the reading for "A"?

The answer to that very specific set of conditions is “yes”. However, for this scenario, you know that the two fridges operate for the same number of hours. For your home-vs-Sears comparison test, run-time(s) is(are) not a known condition.

For the condition of your home fridge and the one at Sears, you don’t know how long each runs. Therefore, you have no idea how much energy each would consume despite the fact that you know the instantaneous power draw. The exception, of course, would be if each fridge ran continuously and always drew the indicated power.

Another problem is that the fridges won’t always draw the indicated power. For example, power use will be different when the internal defrosters are operating. I also suspect that operating conditions “on the showroom floor” (empty fridges, many door cycles and/or long door open states, demo units surrounded by other heat-generating appliances, etc.) are not representative of typical home conditions.

A more useful experiment might be to run each fridge on the Kill-a-Watt meter for a week and then compare a week’s worth of data. I suspect, however, that the essentially uncontrolled store environment would still be a problem.

I agree the “6.5 A” vs “4.5 A” labels could be confusing. These values represent the maximum current each fridge draws under normal worst-case operating conditions, such as starting the compressor motor. The AC circuits and associated breakers must be sized accordingly. Power factor performance might also be an issue. These figures do not represent typical steady-state current draw, just as your casual experiments revealed.

I’ll try to remember to include some instantaneous power reading from my Sears fridge when I post the 3-month performance report tomorrow morning.

Regards,
Jim / crewzer

niel

Re: Energy Efficient Refrigerators

to add to this even if said power draws would be identical along with the other scenarios there is the possibility of differing levels of insulation that can make a vast difference on the time needed to be running throughout the day. the test of time is valuable and 24hrs at say 70 degrees f ambient air temp(or some other standard test temp) around the fridge with specific standard inside temps for the freezer and refrig parts for all fridges in question would be a fair analysis. also the test would have to specify if empty, half loaded, fully loaded, etc. as these are valid variables that can effect its operation too.

System2

Re: Energy Efficient Refrigerators (CREWZER)

In your january 31 answer to my question, you said you would post some fresh information about an old thread:

["My Sears fridge appears to operating nominally when viewed from an annual energy consumption perspective. It exceeds "average" daily energy requrements in the summer, but beats the average in the winter. I'll post a Nov. 1, 2007 through Feb. 1, 2008 update on this discussion thread tomorrow morning"]

Nevertheless, I have not found the new message. May you tell me where to find it?

crewzer

Re: Energy Efficient Refrigerators

Here you go: http://forum.solar-electric.com/showthread.php?t=449

HTH,
Jim / crewzer

System2

Re: Energy Efficient Refrigerators

We live in western-northern Nevada and our relative humidity runs in the "normal" rage of 7-15%. I have been keeping a log of my various utilities for over 10 years now.

I have been preparing to go off grid for 3 years now. Part of that prep was to upgrade my appliances. I had a 1996 Sears side by side and an additional manual defrost freezer. I dumped the side by side for a Whirlpool "refrigerator only, refrigerator" This new refrigerator was actually 1/2 of a set of refer-freezer combo set. The new refer droped my monthly kW usage by 100 kW a month even though it did not have the energy star rating. The consumption tag on it says 4.5 Amps. In observing my Kill-a-watt meter, upon start-up the unit will pull ~540 Watts and quickly drop to less than 100. While in the normal run cycle it pulls ~80-90 Watts. It has the auto defrost cycle that kicks in every 12 hours for 15 minuites and consumes ~440 Watts. With our low humidity, I could probably get really anal and disconnect the defrost heater but there again it only runs 1/2 hour in 24.

As for my freezer, it's a manual defrost. All of the cooling coils are exposed so I can observe the frost build-up inside. There again in our low RH environment, defrosting is only needed about once a year. Since my freezer is in the garage, my defrosting technique is this. Un-plug the unit, take all the frozen goods out, wheel the freezer out into the driveway on my cheep dolly, and melt-out the frost with the garden hose. (Be careful not to hose down the thermostat as it will freeze. I had to pull mine out once, use the wife's hair dryer to defrost & dry it out. The freezer was stuck on 20 below F. Zero to +10 is usually cold enough.) Dry out the excess water with some towels, let the wind dry it for another 15 minutes or so, wheel 'er back in and I'm done for another year. Oh yeah, the consumption tag on this freezer unit is also 4.5 Amps.

The side by side, self defrost's are definately energy pigs! The cooling coils are usually on the freezer side and the excess cold air is either blown or gavitates toward the refrigerator side by vent holes between the refer & freezer compartments.Then there's all the extra seals to leak cold too.


Dennis

Ralph Day

Re: Energy Efficient Refrigerators

Denis
That defrost sounds like too much work!

A quick and easy way is to remove items, unplug unit, by the time you find your ice scraper (for car windows...maybe not in your climate) it's time to scrape. a dustpan can shovel out the peas, carrots and ice. Plug back in and re-load. Total job can take 15 minutes, tops. That depends on how much stuff is in the freezer and how big it is. The freezer hasn't even cooled much by the time you plug it back in. Do allow10-15 munites minimum before powering up (Wayne can explain why).

The few minutes of being unplugged (before scraping) is usually enough to make clearing the ice and frost an easy job. Easiest when someone else does it tho.

Ralph

mike95490

Re: Energy Efficient Refrigerators

Ralph Day wrote: »

A quick and easy way is to remove items, unplug unit, by the time you find your ice scraper (for car windows...maybe not in your climate) it's time to scrape. Ralph

I find it takes about 2 hours to melt the ice out of my freezer. I should do it more often I suppose.

I use a couple of fry pans, full of hot water, and set them on the ice. When they melt down to the coils, then things pick up speed, as they heat the freon in the coils, and it starts to melt the rest of the coils.
(my upright freezer, has shelves made of coils, with wire mesh over the coils, top & bottom, to make the coils into shelves)

Mike, Los Angeles

Ralph Day

Re: Energy Efficient Refrigerators

I guess i should have mentioned my freezer is chest type, 12 cu ft, so not overly large. Wouldn't want to clean an upright with coils in shelves...seen them frosty and it's scary!

ralph

H2SO4_guy

Re: Energy Efficient Refrigerators

How about a Sunfrost RF-19? They are pretty good I hear. We just put a bid on a house that already has one of these and I can't wait to give it a try.

Skip

BB.

Re: Energy Efficient Refrigerators

Here is a long and wandering thread about keeping things cold... In the middle is a discussion of Sunfrost refrigerators and how much less power they use vs a good Energy Star brand (and the SunFrost may actually use more power per cuft of food to keep it cool).

-Bill

SolarJohn

Re: Energy Efficient Refrigerators

My new refrigerator:
Energy-Star-Tag: 499kwh/yr
Kill-A-Watt meter test results: 894.25kwh/yr

I connected my Kill-A-Watt meter to my new refrigerator and watched it for a few days. I observed a higher than expected kwh reading. I reasoned that my test results were skewed because the refrigerator was warm at the beginning of the test. I waited about a week, and then repeated the test. Again, I experienced higher than expected kwh readings, as indicated below:

After 48 hours, my Kill-A-Watt meter read: 4.90kwh.
Therefore, the daily total is 2.45kwh.
The energy-star rating for this refrigerator is: 499kwh/yr
Therefore, the daily total should be 499 divided by 365, or about 1.37kwh per day

I'm disappointed. I want to run it off of solar power, and I'll need to provide more power to it than I had planned.

John

crewzer

Re: Energy Efficient Refrigerators

My new refrigerator:
Energy-Star-Tag: 499kwh/yr
Kill-A-Watt meter test results: 894.25kwh/yr

John,

That’s very disappointing news indeed. That’s higher energy consumption than my previous kitchen fridge (~20 cf side-by-side w/ ice maker and thru-the-door dispenser; circa 1996) and my even older “big” fridge (25 cf, circa 1990).

Frankly, I think there’s something wrong with your unit. Some things to check are the interior lights (do the shut off?) and the automatic defroster. If the steady-state power reading is > ~120 W, then there well may be a bad load.

Other things to check are adequate ventilation (is the air path under the fridge blocked?), nearby heat sources (i.e., heater register, stove), and properly closing doors, and internal temp settings. I seem to recall that my Sears fridge had some sort of packing material at the bottom of the back side that had to be removed (something to hold the defrost drip pan in place during shipping?).

All in all, this is bad enough to justify a warranty repair call. Just make sure your k-a-W meter isn't bad... check it with a known load.


Good luck!
Jim / crewzer

SolarJohn

Re: Energy Efficient Refrigerators

....Just make sure your k-a-W meter isn't bad...
....Other things to check...

When the refrigerator's compressor isn't running, the K-A-W meter shows 10 or 15 watts. (I forget the exact reading).

My tests were done in September, not the coldest month of the year, so I guess I should repeat the test now that cold weather is here. I wonder if readings will go down now that the unit is "broken-in"? I'll also check down below to see if any packing material remains in place. Ventilation is good.

Instantaneous KAW meter readings are good (with known loads), but I've not checked it over time.

If everything else checks out, I'll consider a service call.

Thanks!

John

BB.

Re: Energy Efficient Refrigerators

15 watts will add up... Another 0.36 kWhrs per day... I would prefer closer to "zero" or a couple of watts with the motor off--But who knows with all of these electronic additions to fridges now...

My washer and drier are close to 9 watts apiece when "off"... Turns out, that those 18 watts x 24 x 7 x 365 are almost 1/2 of the total electricity used by my washer/(gas)drier--So, there is now a power strip that turns off the washer/drier when we are not using them.

Also, were you "Making Ice" during this time... That adds quite a bit to the power requirements too.

-Bill

Windsun

Re: Energy Efficient Refrigerators

crewzer wrote: »

John,

Other things to check are adequate ventilation (is the air path under the fridge blocked?), nearby heat sources (i.e., heater register, stove), and properly closing doors, and internal temp settings. I seem to recall that my Sears fridge had some sort of packing material at the bottom of the back side that had to be removed (something to hold the defrost drip pan in place during shipping?).

Good luck!
Jim / crewzer

Many of the new refrigerator and freezers don't have exposed coils, instead they dissipate the heat through the walls of the unit. If you don't have at least 2-4" of air space around the outside of them, they will not work very well.

crewzer

Re: Energy Efficient Refrigerators

When the refrigerator's compressor isn't running, the K-A-W meter shows 10 or 15 watts.

As suggested by Bill, this too may not be a good sign. My fridge registered just one Watt while sitting idle this morning (doors closed, compressor off, etc.)

HTH,
Jim / crewzer

System2

Re: Energy Efficient Refrigerators

SolarJohn:

Many refrigerators have a switch to turn on and off a heater that dissipates moisture.
In my fridge, that heater consumes about 20 watts.
Did you turn that switch off before meassuring consumption with your kill-a watt?

BB.

Re: Energy Efficient Refrigerators

Yes, forgot about the "heater switch"... May be called summer/winter mode, anti-sweat, eco mode, or something like that. Heats up the door edges to keep water from condensing in humid climates.

-Bill

SolarJohn

Re: Energy Efficient Refrigerators

My previous Kill-A-Watt meter test was done in September. I tested again today, in February, when the inside temp is a little cooler. Results:

24 hours - 1.9kwh
Times 365 days, this is 693.5kwh per year

This is much better than my previous test results (894kwh), but still not as good as the claim on the energy star tag (499kwh per year). Another thing I haven't checked is the temperature settings. These get "messed with" from time to time, and I'm not sure they are at the recommended settings at the present time.

John

niel

Re: Energy Efficient Refrigerators

something doesn't sound right john as my old non-energystar roper (i think 21 cuft and about 10yrs old) i measured during last winter for 24hrs at 1.5kwh with my kaw. if they don't make it work as it should i wonder if you can also turn them in to the people who test and give these energystar ratings. if they changed something on those fridges that takes them out of energystar compliance they should know of it.