How to Recycle Thermostats
Wall thermostats containing mercury tilt switches, plus modern digital units. The mercury quantity here dwarfs every other household source.
Quick answer
This is the rare hazardous item with a good take-back program. The Thermostat Recycling Corporation runs more than 3,400 free collection points across 47 states, mostly at HVAC wholesalers, and in eleven states those wholesalers are legally required to accept them. An old mercury thermostat holds around 3 grams of mercury, hundreds of times a compact fluorescent, so it is worth the trip. Digital thermostats are e-waste. Before you go, confirm that a local recycling center accepts the material in its current condition.
- Recycling route
- Check locally
How to Prepare
- 1Turn off power at the breaker before removing a thermostat from the wall
- 2Take the cover off and look for a sealed glass ampoule holding a silver bead, which identifies a mercury unit
- 3Keep the ampoule intact and in the thermostat body rather than removing it
- 4Do not break, tip out, or try to separate the mercury
- 5Take mercury units to a Thermostat Recycling Corporation collection point, which is free to households
- 6Send digital and programmable thermostats to electronics recycling instead
- 7If an ampoule breaks, ventilate the room, do not vacuum, and follow your state's mercury spill guidance
Where to Recycle
- Thermostat Recycling Corporation collection points, over 3,400 sites in 47 states
- HVAC wholesalers and supply houses, required to accept them in eleven states
- Household hazardous waste facilities
- HVAC contractors, who often take the old unit when installing a new one
- Electronics recycling, for digital and programmable thermostats
Special Instructions
The identification step is the one most guidance gets wrong by telling people never to open the unit. The Thermostat Recycling Corporation's own instruction is to remove the cover and look for the ampoule, which is how you tell a mercury thermostat from an electronic one, and that is safe as long as you leave the sealed glass alone. California's toxics department puts the mercury content at about 3 grams per unit, which is roughly 750 times what a compact fluorescent contains, and it is why this item has a dedicated national program when most do not. TRC operates over 3,400 collection sites in 47 states. In California, Connecticut, Iowa, Illinois, Maine, Montana, New Hampshire, New York, Pennsylvania, Rhode Island, and Vermont, HVAC wholesalers are required to accept them free; elsewhere participation is voluntary but widespread. Call ahead, since many sites are trade counters rather than retail shops.
Environmental Impact
A single mercury thermostat carries more mercury than hundreds of fluorescent bulbs, so one thermostat kept out of a landfill or incinerator does more than a year of careful bulb recycling. Recovered mercury is retorted and reused rather than mined, and the thermostat's plastic and metal are recycled alongside it. Millions of these units remain installed in older homes, which is why the program still exists decades after mercury thermostats stopped being sold.
Official guidance and resources
Accepted items and drop-off rules can vary by location. Check the destination before you go.
What’s Accepted
Not Accepted
- Mercury thermostats in curbside recycling or trash
- Loose mercury or a broken ampoule at most collection points
- Thermostats with the ampoule removed, which some programs will not take
- Commercial quantities at household sites without arranging it first
Hazardous Components
- Around 3 grams of elemental mercury in a sealed glass tilt ampoule
- Mercury vapor, released if the ampoule breaks
- Circuit boards and batteries in electronic units, which make them e-waste
Related recycling guides
- How to recycle Smoke Detectors
- How to recycle Fluorescent Tubes
- How to recycle Fire Extinguishers
- How to recycle Aerosol Cans
- How to recycle Automotive Fluids
- How to recycle Propane Tanks
- How to recycle Nail Polish/Remover
- How to recycle Pool Chemicals
- How to recycle Wood Stain/Varnish
- How to recycle Household Cleaners
Recycle thermostats
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