THE Energy Efficiency & Appliance Thread (merged)

nocar · Intermediate Crude Joined: Nov 05, 2004 Posts: 681

Location, location, location.

Lots of people do not think about where they place their fridge/freezer. Obviously the temperature where the coils that give off heat is situated is essential ('ambient temperature'). The cooler and more ventilated the better, since the fridge/freezer has to work less.

Make it work less

And of course you should avoid putting hot or warm things into it, and avoid opening the door.

When it is freezing temps outside, you can put plastic bottles with water outside til they freeze and then place in the fridge. And things that you are going to put into the freezer can be frozen outside first (beware of dogs and such, so they do not steal your food)

nocar

patience · Expert Joined: Jan 04, 2008 Posts: 1523

I want to improve our fridge and freezer this year, and studied this thread with enthusiasm!

Just remembered an old thing from childhood, that a lot of old folks in the 1950's kept the freezer on an unheated porch. They almost never ran in winter... Anybody know the downside to this? I'm thinking that could be hard on a compressor, starting with colld oil, etc. Ideas anyone?

Katuhaukka · Tar Sands Joined: Dec 17, 2006 Posts: 22 Location: earth?

I have always thought why fridges arent built to take air outside through a filtered tube with thermostate or something.
they should be placed against the wall and like that you know.
I'm not engineer , but it's just funny imo that during winter we warm our air and then cool it. - nuts.

am I suggesting something thats in these new fridges?
Is there that sort of models allready?

WisJim

I know a couple of people who are or were off grid, who built their own chest-style refrigerators using Danfoss compressor kits, and who had ducts to bring in outside air when it was appropriate. They worked well, as far as I could tell. At least one of the families later connected to the grid and got a conventional refrigerator to appease their teenage kids.

patience · Expert Joined: Jan 04, 2008 Posts: 1523

Update on my new freezer, a 15 cu. ft. GE, from Sam's Club. Cost $372. The Energy Star tag says 357 KWHR/yr. My Kil-A-Watt says that it's using .64 KWHR/day, with it 1/3 full of meat. The first day of freezing that new load wasn't measured, so this is only a steady state condition. This works out to 234 KWHR/yr, a bit better than advertised. If I add a bit for freezing the new load, say up it to 275 KWHR/yr, I get 275 KWHR/yr divided by 15 cu. ft. =18.33 KWHR/yr/ cu. ft.. I hope to improve on the annual performance by moving the freezer to the unheated back porch.

Because our usage will be very near steady state, this is a somewhat fair trial, albeit for only 5 days. That is, we will normally fill it in cold weather when we butcher a beef, and use from it at a slow rate.

The best I recall, the Sundanzer was advertised at about 100KWHR/year on the 8 cu. ft. freezer, which = 12.5 KWHR/yr/cu. ft.. That is, of course, on direct 12 volts, with no inverter efficiency losses. But it would cost me about $1100 plus freight of around $100 = $1200.

When I run my 120v freezer on 12 volts, I lose about 10% in inverter loss with a Harbor freight 2000 watt inverter, running pretty efficiently at only 118 watts draw for the freezer. (Inverters need to be greatly de-rated to be efficient.) The inverter cost $149 on sale. I did correct for a .01 loss in the Kil-A-Watt.

We are planning to get our home off the grid this year, and just placed the order for 4 more 180 watt Evergreen solar panels, another C60 Xantrex charge controller, and a couple more inverters. The plan is to have two complete systems of 4 panels each, feeding 8 Trojan 6volt batteries, or 1440 watts of panels, total. The first system is completed except for mounting the panels, which I won't do on a snowy roof at the moment.

Our computer, with a flat screen monitor, and wireless telephone system draw about 150 watts, except for theHPprinter, which is a hog at 450-600w. That leaves enough for several CFL lights, and capacity for a fridge, if it isn't too greedy. All these figures are preliminary design numbers, with only short run results, but I am encouraged from what I've seen.

HamRadioRocks · Heavy Crude Joined: Jul 19, 2006 Posts: 108

Everyone knows that running the furnace expends energy directly, since energy (in the form of natural gas, heating oil, propane, wood, or other fuel) is needed for the furnace to work. But there's a secondary effect. The warmer your home is, the more electricity your refrigerator needs to keep the contents inside cold. That's because the refrigerator has to chill the incoming air, and the warmer the inflow is, the greater the energy needed to chill it down.
In other words, there's a neverending war going on between the furnace and the refrigerator, and the result is increased energy use. The furnace is working to heat the air while the refrigerator is working to chill the air.

Thus, lowering the thermostat in winter saves energy in two ways: less energy to run the furnace and less energy to run the refrigerator. Using a programmable thermostat to lower the thermostat further at certain times will extend the energy savings.
I wish there were a way a refrigerator could tap into outdoor air in winter. Since the outside air is cold and dry during most of the winter, little or no energy would be needed to chill it. Also, being able to vent the refrigerator's outflow of hot air to the outdoors in summer would save energy by reducing the energy needed by the air conditioner AND the refrigerator to cool the air.

ohanian · Light Sweet Crude Joined: Oct 17, 2004 Posts: 1090

Your logic is flawed.

Here is why. Imagine that your house does not have a refrigerator. Now your furnace have to work HARDER to make your house warm because an item which gives off heat is missing in your house.

SchroedingersCat · Intermediate Crude Joined: May 26, 2005 Posts: 527

Houses used to have a storage cupboard that could be vented to the outside in cold weather. In the winter this was the fridge. Don't know why that ever went away.

I've wondered why commercial places don't do this with the huge coolers for beverages.
_________________
Civilization is a personal choice.

dooberheim

Some large HVAVC systems have "economisers", which are outside air vents that can be used to add to heat or cooling air flows.

Turning down the thermostat will help save energy. In many cases, particularly if you acclimatize and heat with wood, you can completely dispense with the furnace, which solves the problem the other way.

DK
_________________
Carpe Scrotum!

pstarr

Concerned · Light Sweet Crude Joined: Sep 23, 2004 Posts: 1536

Tanada

If I ever have the financial where with all I want to build an integrated fridge, run the coolant through a heat exchanger to pre-heat the water heater supply tank. The Fridge efficiency goes way up as the coolant/water exchanger is way more efficient than the coolant/air exchanger on the back of a standard fridge. The water heater efficieny also goes up as the water inflow is slightly warmed before heating.
_________________
Oxygen: - An intensely habit-forming accumulative toxic substance. As little
as one breath is known to produce a life-long addiction to the gas, which addiction invariably ends in death.--Isaac Asimov

Concerned · Light Sweet Crude Joined: Sep 23, 2004 Posts: 1536

dunewalker

I agree with ShroedingersCat and pstarr. Living off-grid here in the desert, saving energy in any way conceivable is important. So, I built a cabinet for the fridge, put a sealed door on it, drilled two 4" holes in the floor, one in the upper wall behind the fridge, screened them. Now the fridge is unplugged for most of the winter, as the temps have run to minus 6 degrees F. Ironically, the fridge keeps things inside it from freezing. In the summer, I just keep the cabinet door open & since it's on the northeast side of the cabin, it assists ventilation/cooling. Of cours the fridge is plugged in then, but there is plenty of solar power available during the long days of summer to run it.