As digital and WiFi-enabled thermostats have grown in popularity, most people are just throwing out their older manual thermostats. Many do not realize that these thermostats contain levels of extremely toxic mercury. In this article, we’ll look into the dangers of mercury as well as the proper handling and disposal of mercury-containing thermostats. 

What is Mercury? 

No, not the planet or the car, mercury is a metal frequently used in thermometers, barometers, fluorescent lamps, and many other household appliances. While it is a poor conductor of heat, it is a pretty good conductor of electricity. Due to weak atomic bonds, mercury is in liquid or vapor form at room temperatures. With an extremely low freezing point and an extremely high boiling point, mercury is favored for use in thermometers. It is incredibly sensitive to temperature, expanding and contracting with heat, usually in a glass tube with an associated temperature gauge. 

Why is Mercury Dangerous? 

Mercury is dangerous for humans due to it becoming vapor at room temperature. Once vapor, it is an invisible, odorless gas that is very soluble in fats and oils. After it is inhaled, it can enter the bloodstream and make its way into the brain. The effects of mercury poisoning can be disastrous to the nervous system. While results of eating or drinking mercury are less hazardous because it usually exits the body via the digestive system (though still not a great idea), some mercury is often also inhaled in a vapor form while digested. Where mercury poses the biggest threat to your family is from broken mercury-containing elements. The leaked liquid vaporizes, becoming a toxic gas that lingers in the air far longer than that of water vapor or many other gases. 

Removing Mercury-Containing Thermostats

While many older, manual slider or knob style thermostats contain mercury, most digital thermostats do not. If they do, it is frequently noted on the packaging with an “Hg” marking. To safely remove your mercury-containing thermostat: 

  • Turn the thermostat entirely off. 
  • Shut off power to your HVAC system from the circuit breaker box. 
  • Carefully remove the thermostat from its mounting bracket. Make sure not to drop it, as it likely contains mercury. You may consider laying some form of cushioning below it in case you do drop it. 
  • Before removing any wiring from the thermostat, snap a picture of the connection points with a phone or other digital camera in order to have as a reference for other installation.
  • Disconnect the wiring from the thermostat itself, but do not remove any wiring from the wall. You will need this for your next thermostat. 
  • Recycle the old thermostat as one piece. Do not attempt to disassemble the thermostat. 

Recycling Your Thermostat

An organization called Thermostat Recycling has set up an easy mercury thermostat recycling-center locator on their website. Type in your zip code to find the thermostat recycling collection nearest you. 

Source: http://dtwreckit.com/blog/posts/view/206/mercury-containing-thermostats-why-remove-and-how-to-recycle