On the Rocks

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There is frost on the lawn and a thin layer of ice starting to form on the water buckets. For those living in northern climates, chopping rock-solid ice out of those buckets will soon be a daily chore. Is there an easier way?

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.

For de-icing buckets, there are two choices: units with the heating element inside the bucket, and those that have an external unit. The external units are double-walled buckets with the heating element wrapped around the outside of the inner bucket. The benefits of this system is that the cord stores away (typically in the bottom of the bucket inside a door) so the bucket can be used all year. If the heating element is inside the bucket, then the horse can play with it, and it can also be difficult to clean. More importantly, this method can introduce a path for electricity into the water where it can shock the horse (this is also true for floating or submerged de-icers used for large, outdoor tanks). Horses are hyper-sensitive to electricity, and while a human wouldn’t notice two or four volts leaking into water, that will certainly get the attention of a horse!

What will it cost to run a barn full of buckets for the winter? “Our 5-gallon bucket has a heater in it that is 130 watts,” explains Dr. Chumbley. “Twenty stalls would be 2,600 watts or 2.6 kilowatts. Multiply that by 24 hours and then by 30 days. Now, if your energy cost is 10 cents per kilowatt hour, your cost per month would be $187. But keep in mind that is assuming the buckets were running all the time, which they typically are not. They turn on, heat up, then shut off.”

How do you know if you’re overloading your circuits? “Most circuits,” continues Dr. Chumbley, “are 15 to 20 amps. Using the 130-watt bucket in the example above, we’ll use a little over one amp (1.1 amps) for each bucket. So you could put about 12 or 13 buckets on one circuit to get up to your 15 amps. If you’re using a de-icer for an outside tank, where you’re up to about 1,500 watts, that’s an example of where you can’t put two on one circuit, because each one draws about 12 amps.”

A final note on double-walled de-icers: keep your buckets clean and don’t let deposits build up. The heat can’t transfer as easily through the walls of dirty buckets, and the thermostat might not detect a change in temperature as readily.

OTHER SOLUTIONS

For outdoor troughs, one suggestion is to put a large ball, such as a soccer ball, in the water. The idea is that the ball will move around with the wind, disturbing the water and keeping it from freezing. The chance of this working, says Dr. Chumbley, “…is very, very low. It all comes down to the amount of energy used as the ball moves around. It might mean that the water will freeze at 31.5 degrees instead of 32, but that’s not enough to make it worth using.”

Another idea is to insulate the trough. Manure, dirt and straw bales are common insulators and they do help, although how much is questionable.

Instead, suggests Donna Coffin, an extension educator with the University of Maine, consider using a recycled upright freezer. “They are well insulated,” notes Coffin. “Look for the all-metal freezers and be sure that the compressor has been removed. Many towns require that the Freon be removed professionally so it won’t harm the atmosphere. I also remove all the grates and anything protruding, and if there are any holes, I use silicon caulking to seal them. Lay the freezer on its side on top of 4” x 4” x 2” pieces of wood, to raise the top of the freezer up so the horses won’t put their feet into it.” Also, because the amount of exposed surface area is a big contributor to the rate at which water freezes, cover part of the trough, especially if exposed to wind.

Having fresh, clean water available to your horses is a priority. It can be a struggle during colder months, but with a little extra care, you can keep the ice away.