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Old 09-12-17, 09:58 PM   #6
ctgottapee
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Not too 'negative nancy' your ideas, but there isn't much you can do to improve on the basic chest freezer. However tinkering can be fun, but any minimal gains will be negated by time/cost of any mods.
[*]I will remove the 15W light which turns on when the lid is open.
> It's a momentary use so little to save. As long as you don't take extra time to find things [longer lid is open, more cooling you lose] or use a different light like an overhead one you wouldn't normally use.
Opening the lid once or twice a day for no more than 10secs will use 15Watts the entire year; it would take 67 years to use 1KwH that costs 6-20 pennies
[*]There is about 3cm of space between the condenser coils and the rear wall. I want to increase this by 10-15mm, and insulate the rear wall with 5mm of styrofoam with a reflective coating, to keep the heat off (when testing, the coils heated from 16 to 26C in just 2 minutes).
> The coils already have a insulated air gap to the rear, another 10-15mm won't markedly change the resistance value. Adding more insulation won't make much difference as far as the coils go; and there isn't really any such thing as reflective coating as far as non-solar heat goes. Manufacturers would already do these things if they were effective.
You could try to enclose the coils in a separate enclosure that vented outside.
[*]The freezer walls are already 85mm thick, but I would stick an extra 3-5cm of styrofoam on the front and sides.
> There is a point of diminishing returns on extra insulation, and of course the end product can be a nightmare.
[*]What about the lid and the seal? Are these worth the effort to insulate?
> Making sure the seal is effective is worthwhile, especially on an old unit.
You can use thick firm magnetic seals, and put weight on the lid to keep it firmly shut.


[]Possibly in the future we may change our tariff so that electricity is cheaper at night, then the freezer could be put on a timer to only work the compressor during cheap hours.
> This can work, but you must be careful not to open the freezer often, especially during the day. The issue is temperature swings, and the humidity/frost. You want the food to stay not only good, but not freezer burnt or encourage frost build up. Freezer items are often valuable, like meats and such.

[]I also had a plan to add a second thermostat for refrigerator temperatures...
> I've seen models with this feature. Generally the compressor designs are optimized for the type of use. It won't be efficient, but it will be useful.


>>Other thoughts:
If it has a auto defrost mode, turn it off. The trade off is timing a manual defrost that doesn't take too much time/energy. Also adding insulation internally will short circuit this auto defrost mode, and make manually defrosting very difficult.

Can you dump the heat from the coils elsewhere? Separate enclosure, a hot water tank preheater, run to the bottom of a sump pump well?

Can you get water on the coils to cool them quicker, similar to how many window A/C units do. Of course, it's going to evaporate into the basement, which may be undesirable. The gains here could be trivial.

Spending money on newer units with more efficient compressor designs save energy; the issue is whether the added cost of purchase saves money long term. The new designs also save by keeping frozen food fresher longer.

Good Luck
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