Freezer Performance: Seals, Sensors and Alarms

Freezers quietly chug along in a basement or utility area and are easy take for granted – until they unexpectedly fail. This post is about getting a “heads-up” before a major loss.

Most freezes are NOT equipped with an actual internal temperature readout device or alarm. If yours has none then by all means at LEAST get one like this that has a wired sensor run thru the door seal and an external battery powered readout and audio alarm. You can use it both to adjust the freezer temp setting to the zero to 10 below F range best for beef storage and get an alarm should the freezer or power circuit fail.

Freezer “door seals” are a major performance concern. Accordion pleats and magnetic attraction allow the seal to compress and extend to close gaps of varying size. They are by no means a perfect “hermetic” seal and only slow down the leakage of internal cold/heavy/dry air OUT to be replaced by warm/light/wet room air leaking IN. This is why frost forms on the internal walls and coils. Frost represents the condensation and freezing of room air humidity (water vapor) on these cold surfaces. The more leakage the quicker it forms. Make sure your door seals are undamaged without excess crud in the pleats (particularly along the bottom seal of an upright style freezer) and are not age-hardened. Dirt and crud accumulation in the pleats restrict seal compression, slowly making that portion of the seal less compliant.

Chest freezers are less vulnerable to air leakage because the seal is all at a single elevation with a uniform internal air pressure behind it. Their seal pleats are oriented horizontally and don’t collect crud. Upright freezer seals are faced with a pressure differential between top and bottom due to the tall column of warmer-top and colder-bottom air they are holding in. The bottom seal tends to collect crud from inside the freezer box. Uprights are prone to leak OUT at bottom and pull IN at top.


 

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