That old wall thermostat may contain one or more sealed mercury switches. Keep the complete unit intact and arrange recycling through a thermostat collector or household hazardous waste program.
If it is broken or mercury may have escaped, stop handling it. Keep people and pets away, and use EPA’s spill guidance.
How to Tell Whether a Thermostat May Contain Mercury
Older mechanical thermostats, including some round models, may use mercury switches. Its shape cannot confirm what is inside.
Check the manufacturer, model number, manual, packaging, and labels without opening sealed components. An HVAC professional or collection program can help when you are unsure.
Do not dismantle the thermostat or remove a mercury ampoule. EPA advises keeping mercury-containing devices isolated and sending the complete device to a recycler or consolidation site.
If the Thermostat Is Still Installed
Ask an HVAC professional to remove it, especially if you are unsure about the wiring or mercury switch. Tell the contractor that the thermostat may contain mercury.
Before the appointment, ask who will take responsibility for recycling the removed thermostat. Do not assume it will be recycled unless the contractor confirms the handoff.
Where to Recycle an Intact Thermostat
EPA recommends taking old mercury thermostats to a state or local household hazardous waste center for recycling.
The Thermostat Recycling Corporation also maintains a nationwide locator. Its listings are based on recent collection activity, but TRC still advises calling before you travel.
Ask whether the site accepts thermostats from households, whether the cover must remain attached, and whether there are residency, appointment, or quantity rules.
State law may impose stricter requirements. Check your state environmental agency before choosing a disposal route.
How to Hold an Intact Unit for Drop-Off
- Leave the thermostat and mercury switch whole.
- Replace the cover if it has been removed.
- Keep the unit protected from crushing or impact.
- Follow the collector’s packaging and transport directions.
- Do not place it in household trash or curbside recycling.
If the Thermostat Breaks
Do not vacuum or sweep spilled mercury. Those actions can spread mercury and increase exposure.
Keep people and pets out of the area. Start with EPA’s mercury spill page, which routes you by the amount and source.
If more mercury escaped than a thermometer contains, use EPA’s larger-spill instructions and contact the listed authorities.
Replacing a Mercury Thermostat
Digital, programmable, and smart thermostats generally provide mercury-free replacement choices. Choose a model compatible with your heating and cooling system.
An electronic replacement becomes electronic waste at the end of its life. Check its manual and local electronics program rather than putting it automatically in curbside recycling.
For another mercury device, see how to dispose of a mercury thermometer.