Maintain -80 freezer temperature? - How can we keep it from dropping too quickly? (Apr/29/2009 )

We keep having a problem with our -80 ultra low freezer. The temperature keeps dropping sometimes to about 69 or so and of course setting off the alarm. Aside from having the freezer serviced (which we will check into), are there other ways to help keep the temp low? Obviously we're minimizing the time spent with the door open. Specifically, someone recommended throwing in more racks and empty boxes or ice packs to have something that "keeps some of the cold" while the door is open. Is that usually effective? Can we pack it with water, another chemical or blocks of insulating (plastic or foam) or conductive solids (metal)?

Thanks.

assembler01 on Apr 29 2009, 10:52 PM said:

Some air ventilation might help so that the waste heat of the compressor can escape (if there's not enough air exchange in an already heated up room, the heat exchanger might not work properly)

The ambient room temperature can have an effect on some freezers for example our - 80 C sometimes drops to 70 ish during the summer but we never have trouble during the winter.

Also if ice has built up around the door or the inside compartment doors, you should use a hair dryer to melt the ice very quickly, this allows the doors shut properly and keep the temperature down

As for internal ice boxes etc i dont think this will work to cool a whole fridge to - 80.

If it is possible try to keep the room the freezer is in cool, if the room is prone to heating up, is it caused by by direct sunlight? or other lab equipment giving off heat?

If so maybe move lab equipment to another room or try to darken out the windows of the room.

Cotchy.

Freezers and fridges are most efficient when they are full, as the mass inside them helps maintain a stable temperature when the door is opened. Being full also means that less air is displaced each time the door is opened, so the temperature stays more consistent.

If (as I suspect it is) this is an upright -80, make sure that the door is opened for the minimum time possible. In other words, don't stand around looking for the samples in the box(es) while the door is open, shut the door and then look for your samples. Also make sure that you only open those parts of the freezer that you need to, don't open all the internal dividers if you don't have to.

assembler01 on Apr 30 2009, 03:22 AM said:

You can try even -100 ultra low freezer. We can provide you customized cooling solution as per your specific needs -- upto -100 to -120 degree Celsius with less consumption of electricity/power. Just for your reference, we have a successful track record in installing ultra low temperature systems. Let me know if you have any specific need around ultra low temperature system. I would be more than happy to discuss it further,

yeah i also feel the temperature of the room your -80 is in matters!!! i prefer cooler rooms!! and less time spent with door opened!!

Besides having more mass in the freezer check the coils and air filter. You can easily dust off the coils and wash the air filter periodically.

Make sure there is plenty of space around the unit so there is proper air exchange.

Yearly, you should empty the freezer, clean it and start up again. Ice build up around the door can damage the gaskets and also warp the door.

-80's run on a two stage compressor. You should also monitor the temperature and if you notice that it can not get down to temp you may have a coolant leak or the compressor may be ready to give out.

We have a Sanyo that is over 10 years old with no problems. Revco units seem to last about 5-6 years then the compressors give out. It is cheaper to replace the compressor than purchase a new unit. Service providers usually provide loaner units if they are notified in advance.

Replacement compressors are about $2.5-3K and the units must be removed for repair. Labor is about $1k.