On the Rocks

A BRIEF CHEMISTRY LESSON

Although water freezes at 32 degrees Fahrenheit (for this article, all temperatures are assumed to be in Fahrenheit), that doesn’t mean a 5-gallon water bucket will freeze solid as soon as the temperature dips to 32 degrees. There can be a significant temperature gradient within the bucket, so the top will freeze while the bottom water may still be at 40 degrees. The ice cover may actually slow down the freezing process, but of course, nobody wants ice in their buckets.

The formation of ice isn’t determined by the cold air coming into the water, but rather on how fast heat escapes. So how quickly your water freezes is a function of the insulation around the bucket. Another factor is the amount of surface area; the more area exposed, the quicker water will freeze. Because metal loses heat faster than rubber or plastic, and troughs have a much larger surface area than buckets, those big, metal outdoor troughs will be the first to freeze.

The first rule of thumb is to be sure to remove all ice from the buckets before refilling. Explains Dr. Philip Chumbley, Director of Research and Development for Allied Precision Industries in Elburn, Ill., “The ice can actually be colder than 32 degrees so it could be a source that sucks up heat. Even if you add warmer water and the ice melts, it can still cause the water to freeze faster. For example, let’s say you add water that is at 40 degrees. It takes 80 calories per gram to melt the ice as opposed to one calorie per gram to reduce temperature, so even a little bit of ice will cool 80 times as much water down a degree as it melts. So keeping some ice in your buckets when you refill them can make a significant difference in how fast the water freezes.”

INSULATORS

Insulated bucket holders are popular in some barns. Buckets are placed into them and they provide insulation around the sides and bottom. The advantage is that they use no electricity and require no maintenance. Do they work? Yes and no. “The problem,” explains Dr. Chumbley, “is that most of the heat is lost from the top of a bucket, not the sides or bottom. So it might mean the difference between the water freezing in an hour instead of 40 minutes. There is also no rating system for them. But the thicker the insulation, the more effective the unit.”

HEATERS AND DE-ICERS

The terms ‘de-icer’ and ‘heater’ are used interchangeably by many, but they are not the same. Heaters heat water and don’t shut off; a de-icer is strictly for keeping ice from forming. They have thermostats built into them so when the water gets below a certain temperature, the de-icer will turn on, heat the water up, then turn off again. The advantages to de-icers is that they shut off once the temperature is raised above freezing. This decreases the fire hazard and also saves energy. [Editor’s Note: Many de-icing buckets are marketed as “heated buckets” because so many people confuse the two.