Energy savings of a ' fridge

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You claimed 1.25 times as much energy to move the heat from the kitchen to the outdoors as is consumed by the fridge in article
heat from the kitchen to the outdoors.

What does that have to do with the 3:1 rule-of-thumb which I claimed was for an air conditioner? As in the air conditioner's cost of pumping the fridge's heat out of your kitchen being about 1/3 of the fridge's contribution to the electric bill as opposed to your claim of 1.25 times as much?

Not true that most fridges are busy making ice 24/7, nor that this is an argument that the air conditioner contibutes 1.25 rather than .3 times as much to one's electric bill to dispose of the fridge's heat as the fridge contributes to one's electric bill.
- Don Klipstein ( snipped-for-privacy@misty.com)
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Don Klipstein writes:

Simply an observation that if it cost $1 to pump some quantity of heat from inside the refrigerator to the kitchen, it is going to cost about that much to pump it again from the kitchen to outdoors, plus the additional heat generated by the first pump.

The 3:1 rule applies to one hop, moving heat from one place to another. For an air conditioner you're sinking into the outside world on one thermodynamic path, so it's one hop. A refrigerator has multiple paths, and ultimately sinks into the room air, so the heat from making ice has many hops, and the 3:1 rule does not apply. It can be worse if you're air conditioning, or better if you're heating.
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However, essentially all of the net heat output from a fridge is from the electrical energy consumed by the fridge. The heat being removed the fridge is heat that went into it from the kitchen.
Hypothetically, put a fridge in a large black box. So now you have a black box with a power cord coming out of it. The heat energy coming out of this box will equal the electrical energy going through the power cord. The law of conservation of energy does not care about what is inside this black box.

So a fridge consumes 1 KWH to pump either 3 KWH or some other quantity of heat out - but the heat removed from the fridge is nearly entirely heat that went into it from the kitchen. The net heat output of the fridge during a time it has consumed 1 KWH of electricity is going to be pretty close to 3414 BTU, which a good air conditioner can pump from the kitchen to the outdoors with about 1/3 KWH of electricity.
- Don Klipstein ( snipped-for-privacy@misty.com)
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On Apr 21, 8:43 pm, snipped-for-privacy@manx.misty.com (Don Klipstein) wrote:

Get a KaW meter and test a new one, instead of guessing, bs ng discusing bs to death. I mean who cares, it works. Ive bought over 10 last year, they work. They save as advertised .
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Don Klipstein writes:

So you claim to make ice without a sensible heat gain (which burdens the A/C) and corresponding latent heat loss (which does not)?
In thermodynamics and refrigeration, the money is always in the phase changes. Conduction losses are small change. Which is why the DOE test is silly, because it deliberately excludes any phase changing.
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Freezing water does release heat which needs to be transported outside. But how much ice do you make? How many BTUs per month is that, compared to the heat leakage through the refrigerator walls?
Our refrigerator has ice cube trays, not an automatic ice maker, so I'm aware of exactly how often it's freezing water. It ends up being less than one cube tray per month. I can't believe that's a significant fraction of the heat load for an entire month.
    Dave
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ransley writes:

Please. $20/month worth of electricity won't run a TV set, much less heat, lights, or appliances.
I don't think it is even possible to get a $20 bill from our utility. The fixed charges are more than that.
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wrote:

My utility has fixed charges closer to $5. The total per-KWH portion of my bill is close to 14 cents. My most recent electric bill for my 1-bedroom apartment was $33 - including elctric stove.
- Don Klipstein ( snipped-for-privacy@misty.com)
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On Apr 17, 9:01 pm, snipped-for-privacy@manx.misty.com (Don Klipstein) wrote:

An electric stove costs alot to run just like electric heat, Our fixed charges are zero for electric at 13.6 kwh now, Ng is 9$. 20 a month for tv, if you watch it 8 hrs a day every day a new tv might cost 10-15 for me. Obviously few know where they use energy or how to lower it, thats a shame, no wonder our country wastes the most energy.
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Gees then why is my bill 30$ or so a month in winter , when you educated folks cant save a penny and pay near 100 bucks a month in winter!
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Non cfcs, thats funny, so why dont home AC units benefit that same 75% increase that my new frige gave me, why, because its not the Cfcs
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Well I guess they could, IF you wanted to increase your home insulation and anti-infiltration standards as much as they have with refrigerators.
..

--
Joseph Meehan

Dia \'s Muire duit
  Click to see the full signature.
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On Tue, 08 Apr 2008 21:41:06 -0400, C & E wrote:

Without the kids peeking in the frig door every few minutes we save a bunch.
Now they have kids that also have kids.
Serves them right!
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My new unit uses about 4-5$ a month, my old unit maybe 15$ a month, yes its true but I thought new standards were adopted in maybe 93, www.energystar.gov has ratings on all units and a full lowdown on when new mandates took place. Get a Kill-A-Watt meter and find out what your frige consumes. Payback can be 4 years on new units.
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ransley wrote:

Not in my case, according to their website. According to them, my old old fridge costs $82 a year to run, and a new one would cost $30. Call it 50 bucks a year savings. What does a new entry-level 22 cu side-by-side cost these days?
(google google google)
Hmm- looks like about a thousand bucks. That works out to a 20 year payback?
Even if I downgrade to a smaller fridge, for say $500, that is still a 10-year payback.
Think I'll keep this one till it craps out.
I probably oughta vacum the coils, and maybe turn off the icemaker, since I never use the ice, though.
-- aem sends....
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Read how the tests are done, they simulate a family of four I think with alot of use, how you use your frige or how much the door is open is alot of it, my cost was at 0.125 kwh with a kill a watt meter with a Sears unit that was when I bought it the most efficent I could find from EnergyStar charts. Now my rate is near .14kwh so costs are up.
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ransley writes:

No. I cited the CFR earlier in the thread: No doors (that is, they're never opened during the tests), no contents, no ice making or storage. A thoroughly absurd set of conditions that was chosen to make the testing easy and way optimistic.
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$52 a year savings, thats at todays electric price, in 5-10 years it will be double the way oil is at over 100 a barrell . Its really do you want to fix an old unit, or get one more efficient.
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Yeah, I'm not inclined to throw out something that's still working OK.
But when our 20-year-old refrigerator wouldn't hold temperature in the summer any more, the energy consumption ratings were one of the things we considered when looking for a new one. I expect that's their major purpose - not to convince people to discard older working equipment.
    Dave
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OK, here's one data point in the comparison:
We were gettting a new fridge to replace an old one that was about 10-15 years old (I don't know the exact age because the previous homeowners bought it.) Shortly before the new fridge was to be delivered, we plugged the old one into a kill-a-watt meter, and recorded the usage over a 1 week period. Result was 2.5 kWh per day electrical usage. After the new one was delivered, we plugged in the same kill-a-watt meter and recorded the usage over another 1 week period. Usage was 1.0 kWh per day. So the old fridge used 2.5 times as much electrical energy to run. This was measured with a similar load of contents in the two fridges, with similar door opening and closing frequencies, same time of year, so the house interior temp was about the same between the two measurements, same kill-a-watt meter used, so any meter calibration bias would cancel out. New fridge is somewhat smaller than the old fridge, old one was something like 21 cu ft, new one 19 cu ft. I think, so that could explain part of the energy use reduction.
When we bought the new fridge (this was about a year ago), we were told by the salesman (so take this for what it's worth ;-) ), that fridges had recently gone through a redesign to make them much more efficient, but lower reliability. He said manufacturers had reduced their compressor warranty periods from 5 years to 1 year.
Ken
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