Thermostat Recycling at Honeywell

Honeywell Corporation, the leading U.S. manufacturer of thermostats, launched a pilot program this past January to collect and recycle old mercury thermostats. The pilot program is running in Minnesota only, because—in an example of environmental regulations working at cross purposes—existing federal and state regulations severely restrict collection and shipping of hazardous wastes, even if doing so would facilitate recycling. Officials from Florida and New Jersey are looking into implementing the program soon, and Honeywell hopes to expand the program nationally as soon as pending changes to federal regulations make that feasible.

The problem with thermostats is that most of them work by means of a mercury switch—a sealed glass vial with electrical contacts at one end and 2-3 grams of mercury that either completes or interrupts an electric circuit through the vial. Mercury thermostats are a small, but not insignificant, source of mercury in solid waste. According to Honeywell, there are roughly 40 million mercury thermostats in use in the United States, and about one million removed from service each year. If each one contains three grams of mercury, that amounts to about 3 1⁄2 tons of mercury disposed of per year. A 1992 EPA report estimated that considerably more mercury (11 tons) enters the waste stream from thermostats each year—2% of all mercury in solid waste.