Mercury Thermostat Facts

How much mercury does each thermostat contain?

The majority of mercury-switch thermostats recovered by TRC contain approximately 2.5 grams of mercury.  However, the amount of mercury in a thermostat is determined by the number switches in the thermostat.  Each switch contains approximately 2.5 grams of mercury and some thermostats may have as many as four switches. 

Is it safe to have mercury thermostats in my house?

Yes, mercury-switch thermostats are safe. In normal use, the consumer is never exposed to the mercury, which is entirely contained in a glass bulb. Thermostats are specifically designed to protect and hold the mercury inside.  The bulb is protected by a sturdy thermostat casing. Nevertheless, it's prudent to handle thermostats with care.

A mercury-switch thermostat poses a risk to the environment when it is crushed and/or incinerated when improperly disposed in solid waste.  The TRC was founded by thermostat manufacturers to make it easy and convenient for contractors and homeowners to properly dispose waste mercury thermostats.

How do I know if my thermostat contains mercury? Carefully remove the cover of thermostat and check to see if it contains a mercury switch.  If it contains mercury you will see glass ampoule containing silver metallic liquid attached to the thermostat.

How many mercury thermostats remain in use?

There are no reliable estimates of the number of mercury thermostats that remain in use in the U.S. Many states have banned the sale and/or installation of mercury thermostats and manufacturers have ceased production and/or introduced alternatives into the market such as digital programmable models.   As the use of alternatives has grown, the number of mercury thermostats in use is declining and will continue to decline over the next several years.

I’m a homeowner, where do I dispose of my out-of-service mercury thermostat.

Check with your local hazardous waste program to determine if they accept mercury thermostats.  If not, check with you local heating and cooling parts supplier.  TRC strongly encourages its wholesaler collection locations to accept mercury thermostats from anyone.