Toxic mercury in old thermostats

Cool Talk with Hartzell's | Your HVAC Questions, Answered! · Jun 15, 2026 · 19m · transcript

Give Use A Shout

DAVE: If you've got an old round Honeywell thermostat on your wall, the kind with the little mercury switch inside, you're sitting on a small environmental hazard. I pulled one off a wall in Okarche last week, and when I tilted it, you could see that silver bead of mercury rolling around in the glass tube. That's toxic stuff. Most people have no idea they're there, and even fewer know what to do with them when we swap them out.

I'm Dave Hartzell at Hartzell's Heat & Air in Kingfisher, Oklahoma. 45 years in the trade, Master HVAC license. On Cool Talk I cover the stuff central…