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Old 05-02-13, 02:29 PM   #5
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Originally Posted by stevehull View Post
I guess I don't understand. You are using the EPA estimate as the prior standard? I would suggest running the unit as is, without the modified thermostat, and NOT using the EPA estimate. Then you have a true baseline allowing an apples to apples comparison.

I supplied two graphs, the first one was used as a baseline. The yellow bar indicated to me that the asymptote would fall pretty close to the EPA number. That was close enough for me. There is a reason that I used 'hasty' in the title.

If you'd like greater certainty, please try the experiment yourself. That's the way science works.

Originally Posted by stevehull View Post
It could be that the new thermostat is better - but why? The insulation is the same, the compressor is the same - what is different?
The difference is that I'm not demanding the unit to chill the box down to 0 degrees F, I'm only asking it to go to 38 degrees F.

It all has to do with Carnot's Efficiency Theorem.

It a matter of delta-T and the work required to achieve some delta-T.

As a freezer, asking a box to get 60 - 0 = 60 degrees colder is an act against nature. To perform this act, considerable work is required.

As a refrigerator, asking a box to get 60 - 38 = 22 degrees colder is a lesser act against nature. To perform this lesser act, less work is required.

Es claro?

Also, I've heard people wondering as to why a converted freezer was so much more efficient...

Some say that it is because you don't dump air every time you open the door. I doubt that this is such a great factor, because the energy to chill down a freezer full of air is not so much.

Some say it is because the insulation is thicker. This would be a pretty large factor. That was one of the reasons I jumped on this unit, because it didn't have much more insulation than a refrigerator.

Some say that it is because the freezer is built to be more efficient, else the cost of operation would deter people from owning one. I think that this actually might be true. At least comparing my conversion and what I estimate it's energy use to be, to a refrigerator of the same size. So with a converted freezer, you're taking a fairly high efficiency refrigeration system and lowering the physical demands on it.

Thicker insulation would be better...

Not dumping air would be better...

Not stooping over to get a cantaloupe is not so bad.

I'm not an HVAC technician. In fact, I'm barely even a hacker...

Last edited by AC_Hacker; 05-08-13 at 01:55 PM..
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