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Piwoslaw 06-04-12 05:44 AM

Freezer in cold basement
The wife and I are thinking about getting a small chest freezer to store seasonal fruits and veggies. It'll go in the basement, the temperature of which is 5-20C lower than the rest of the house (15-18C in the summer and 2-5C in the winter).

First question: Freezer units are rated to work in ambient temperatures above +10C. Will it be safe to use it in the basement in temps close to, but rarely below, freezing? Supposedly the compressor's oil gets too thick to lube things properly. I've read about refrigerators and freezers in unheated barns and garages which work for years, but many were wired to turn off below a cetain temp.

Once in place, I plan to add foam insulation around the freezer, and maybe thermal mass inside, which together with the low ambient temperature and opening it only 1-2 times per week would allow the compressor to turn on only once per day, hopefully reducing the amount of times the thicker oil could be a problem.

Second question: I've also read about people putting a 60 watt lightbulb next to the compressor to keep it warm, so maybe I could have a more efficient IR bulb or heating pad prewarm the compressor before it turns on?

Now the bonus question: New or used? The new units have better insulation and much more efficient compressors, and apparently can hold temperature for up to 36 hours and use only 0.5 kWh per day. The used ones available locally are cheaper, but leave some room for improvement as far as efficiency goes. They need from 0.8 to 1.5 kWh per day.

MN Renovator 06-04-12 10:02 AM

1. My refrigerator survived two winters with temperatures sitting at around 5 degrees when I was out of the house or sleeping and I spent a bunch of time out of the house. Seems fine, I had to adjust its mix control to max for the freezer and turn the refrigerator colder because the refrigerator was close to ambient and the refrigerator has the thermostat and the freezer was just a air opening that gets bigger or smaller depending on the temp setting. I don't think you'll have an issue.

If I plug in a warm mini-fridge in a 25c house in the summer it will run 25 minutes to get to 17 degrees(set to coldest setting). When I did the same with it in a 5c house last winter it ran for 5 minutes and the condensor coil wasn't even a normal room temp when I was done and the compressor wasn't standard room temperature yet. Oddly enough both the mini-fridge and full size fridge both use 150 watts.

1A. You won't need thermal mass inside, your food is the thermal mass. Get a unit that is properly sized so it is almost always full or close to full.

2. 60 watt light bulb versus 60 watt IR bulb, both are just as efficient at generating the same amount of heat. If you want to use a 60 watt light bulb or a pad heater you will burn far more energy than the freezer will when running in a cold basement and also extend the runtime duration because that warm compressor is going to heat the refrigerant. Also keep in mind that as soon as it fires up, it will be circulated with the cold refrigerant in and around the freezer too so the compressor might cool right off initially. I don't think its worth trying to heat the compressor unless you are getting to below freezing. Even a straight 30 weight non-detergent oil is rated for about 5c, I don't think the oil will have that much trouble circulating.

Bonus. I'd search whatever is the same as Craigslist in Poland for a used unit and see if its model shows up on the Energy Star list(if its also sold in the US), or whatever energy rating system would apply to you. If saving money in the short term is a big deal, get a used one but if you can't find something efficient, I'd buy new and get an efficient model otherwise you'll pay more in the end. I'm facing a similar issue, I have a new fridge that was put in my house as a replacement to a 25 year old one prior to them selling the house and paying the full price on a new efficient fridge versus one that not too long ago had its government energy regs updated to force it to be more efficient is a tough choice as the payback period is long. ...but if you don't have a freezer in the first place and need one then the decision is easier. My vote is new unless you have a way of checking a used one if its rated for efficient energy use.

Piwoslaw 06-04-12 01:35 PM

I didn't think about the cold refrigerant instantly cooling the compressor after cycling on, so I guess that heating it prior to startup would be a waste.

The place I'll put the freezer in the basement can get close to freezing because the of the proximity of the air intake vent for the (open combustion chamber) boiler. The air coming into the basement through the vent can be as low as -8C during the coldest days, though I plan to duct that air closer to the boiler. Also, in a longer time scale, the basement will get better insulation and sealing, and DHW tank, so hopefully the lowest basement temperatures will be higher with each renovation. The small amount of heat from the compressor may also raise the temp slightly.

Unfortunately, the used freezers I've seen in classifieds here are at least 10 years old, so I doubt that there would be any reliable energy usage data. The numbers I gave earlier are estimates based on what I've heard/read in random places. The ads rarely specify the model, only the volume of the freezer and the wattage of the compressor. At the end of the street there is a guy who services appliances, so I may ask him if he has any used models and if he knows anything about their power consumption.

Looking through new units I found a Whirlpool (model 2010 or something) which has a good A+ energy rating, and has an ECO function, which slightly raises the temperature when partially full. The downside of new units is that their coils aren't exposed, as in the older models. Probably not much of a problem if I plan to run the compressor for less than hour each day.

strider3700 06-04-12 01:41 PM

I had no space in my old house so I kept a small chest freezer on the outside porch. I put foam board on the top to keep it dryish and keep the direct sun off in the summer. In the winter I had to scrape snow off of it regularly. water sometimes would get between the seal and build a massive icejam on one side of it in the freezer. temps ranged from +30C to -10C.

5 years later it's in the basement of my new house and working just fine although a bit of spot rust from it's hard days outside.

RobertSmalls 06-05-12 02:23 AM

Regarding the bonus question, add up the total cost of ownership, and try to account for the intangibles. Perhaps you want to account for the environmental impact of having a new fridge manufactured, so apply a $50 penalty to the "new" option. You don't like buying electricity, so bill that at a higher rate than you actually pay.

I ran some quick numbers, assuming you're going to buy the unit now, operate it every day for 5 years, then sell it. You'll have to plug in your own numbers, but my spreadsheet says you should buy new if you can get it for within $200 of the used price.

Piwoslaw 06-05-12 02:38 AM

Yeah, 3R (Reduce-Reuse-Recycle) is why I'd like a used unit, but I know that in some cases it just doesn't work out. When I have all the info on my options I'll have to make a decision. Would a new model be more susceptible to operating in lower temperatures than an older (10-15 y.o.) unit?

One of the reasons I'm aiming for the compressor to turn on only once per day is that I plan to re-tariff our energy so that we pay less at night (but more during the day).

RobertSmalls 06-05-12 03:00 AM


Originally Posted by Piwoslaw (Post 22288)
One of the reasons I'm aiming for the compressor to turn on only once per day is that I plan to re-tariff our energy so that we pay less at night (but more during the day).

Any good freezer should be able to "coast" for 12 hours without too much swing in temperature.

Ryland 06-05-12 04:54 PM

Chest freezers are much more likely to be in basements or unheated garages then fridges, so I wouldn't worry about it to much, if you are worried about it tho look up the specs on it and see if there is a ambient temp range that it's designed to work in.

PaleMelanesian 06-05-12 05:15 PM

Do you plan to use it for many years? I'd buy new and choose a highly efficient unit. If you use it for the full lifespan, the added cost of new manufacture is minimal compared to buying two used units for the second half of their lives. You're also directing the marketplace value efficiency a tiny bit more than it would otherwise.

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