This week's blog post comes courtesy of one of the original founders of the Freezer Challenge, Allen Doyle. When Allen was at UC Davis, he and Kathy Ramirez-Aguilar of CU Boulder had the idea to start a friendly freezer competition between their universities to see who could save the most energy. Their friendly competition has become the International Laboratory Freezer Challenge.
Read Allen's post below for some great tips on reducing ice build-up in your freezers.
Blast the Ice Jam
Ice build-up blocks access to samples, indicates a leak gasket, or inhibits freezer performance. Blast the ice jam this month as part of the Freezer Challenge!
Clean off the door frame and gasket, and sweep off the shelves.
The good news? You don't always have to do a complete defrost. Here are some quick tips for removing ice:
When is it time for a defrost?
Defrosting freezers has been likened to cleaning out the garage, except most people prefer the latter. Looking into research freezers, you might think that ice build-up is a good thing. Maybe it 'proves that the freezer is working' or 'insulates the freezer when the door is opened'. In fact, rapid ice accumulation in your freezer may be the result of a leaky door gasket, too many door openings, or neglect... Rather than protecting the freezer, large amounts of ice may force your freezer to have to work harder than usual to maintain temperature, and it may lead to warm pockets because of poor air convection.
If you can't access samples easily, have clear ice build-up, or have more than 1/2 - 1 inch of frost on shelves and samples, it's definitely time for the Big Thaw.
What's the best way to defrost a freezer and protect samples?
Take care of your samples by temporarily storing them in a freezer with extra space. Some universities even have spare freezers that you can use, just check with your department. You can also put them in coolers or walk-in freezers, pre-cooled with dry ice and more dry ice on top.
To defrost a freezer, Dacko recommends "defrosting the freezer for 48 hours with the door ajar, and then restarting the freezer. Sometimes this will take care of temperature issues", he adds.
At the Freezer Challenge we recommend using basins and adsorbent towels placed around the freezer and under the open door to avoid puddles on the floor. We suggest using cloth towels and/or reusable adsorbent pads. Setting up a fan in front of the open door will accelerate the defrost.
Our lab is busy! When will we find the time to do this?
Try 'Freezer Fridays', an idea conceived by the Michaelson Group at UC Davis. Pick a two-hour block of time to bring the group together for freezer scrape-down, sample cleanout, and eventual defrost. Try this for one month and see what you discover hidden in your frosty freezer...
Removing ice from freezers allows the compressor to work faster, leading to longer compressor life (aka longer freezer life) and reduced energy use. Whether you choose to do a complete defrost, or simple remove the ice shelf-by-shelf, we at the Freezer Challenge award points to labs that do the smart thing and properly maintain their freezers.
What's in a Name?
If you've had a chance to look at your Freezer Challenge score sheet, you might have noticed a unique nomenclature for some of the freezers, namely UULT and ULT for ultra-ultra-low temperature freezers and ultra-low temperature freezers, respectively. Why are we using those terms instead of -150C and -80C?
Calling them 'minus 80s' and 'minus 150s' naturally encourages us to set them to those temperatures. This would be the same as if we called our home refrigerator the 'plus 4' - we'd all likely think our refrigerator needed to be set to exactly +4C. But it doesn't. The same is true for lab freezers. UULTs and ULTs don't necessarily *need* to be set to -150C or -80C, as we'll see later in the Freezer Challenge. So from here on out we'll be using the temperature-neutral terms UULT and ULT.
We haven't come up with a good name for the -20C freezers yet, so if anyone has any suggestions we'd love to hear them!