How does the mercury in a thermostat work?

Mercury thermostats contain bimetal coils that contract and expand with room temperature. When the coil contracts or expands, it activates the mercury switch, which opens or closes a circuit to make the furnace, heat pump, or air conditioner turn on or off.

Can you still get a mercury thermostat?





Mercury thermostats were the standard for nearly 200 years, however they haven’t been made since the early 2000s. New digital thermostats and programmable thermostats are designed to work without mercury. This is due to the hazards that have been discovered to be associated with mercury.

What type of thermostat uses mercury?

Many thermostats use mercury switches, but as long as a thermostat is intact, it isn’t dangerous. Electronic and magnetic snap switch thermostats don’t contain any mercury. To identify whether a thermostat contains mercury, remove the front plate. If one or more small glass bulbs are inside, they contain mercury.

What replaced mercury in thermostats?

A digital electronic thermostat has no moving parts, no mercury, and will always remain efficient over its lifespan, which can be longer than 15 years. It is estimated that by using an electronic thermostat over a mercury filled type, the average homeowner can save up to 30 percent on energy costs alone.

How does a bimetal thermostat work?

Bimetal Thermostats use two different kinds of metal to regulate the temperature setting. When one of the metals expands more quickly than the other, it creates a round arc, like a rainbow. As the temperature changes, the metals continue to react differently, operating the thermostat.

When did they stop using mercury in thermostats?





manufacturers in the U.S. – General Electric, Honeywell, and White-Rodgers. These companies reported that they phased-out the manufacture and sale of mercury-added thermostats in October 2009. Since 2001, many states have passed legislation restricting the sale of mercury-added thermostats.

Should I replace my old mercury thermostat?

Myth:Mercury-bulb thermostats should be replaced because they are inaccurate. Fact:Mercury bulb thermostats are among the most accurate for temperature control within the HVAC industry. Cheap electronic thermostats provide inferior temperature control. Myth:Mercury bulb thermostats are hazardous and should be removed.

Can you replace a mercury thermostat with a digital?

Quote from the video:
Quote from Youtube video: The second thing you've got to do you have got to take a picture of the current and existing wires or you have to take your notepad out and write all the wires down with the colors.

How do I know if my mercury thermostat is bad?

There should be an open circuit when the mercury is not contacting the wire contacts and a closed connection when it is. If the thermostat fails either of these simple checks, it is defective. The easiest way to check thermostat function is to jump across the terminal screws with a jumper wire.

Do Honeywell thermostats have mercury in them?



Mercury is typically found in older mechanical thermostats like the Honeywell Round T87 and rectangular T8090. NOTE: Do not place your old thermostat in the trash if it contains mercury in a sealed tube.

Are thermostats hazardous waste?

Thermostats require special handling. Thermostats that contain mercury must be disposed of as hazardous waste. Please visit Thermostat Recycling for drop off locations close to you.

How do you remove an old mercury Honeywell thermostat?

On most models, you can simply pull the thermostat straight away from the wall. Pull firmly, being careful not to rip the base off the wall at the same time. Some thermostats might have a button or latch that you need to press to release the cover. Removing this cover should reveal the wires and terminals.

How do I change my old thermostat to digital?



Quote from the video:
Quote from Youtube video: All right once you cut the power you're going to go ahead and pop off the front of your old thermostat here. And you'll see there's a bunch of different colored wires here.

How do I know what model Honeywell thermostat I have?

How to Identify a Honeywell Thermostat

  1. Remove the thermostat from the wall by unscrewing the mounting plate.
  2. Flip the thermostat itself over and look for the model number, which should be printed somewhere on the back of the case.

Why is my Honeywell thermostat not working?

There are a number of reasons why your Honeywell thermostat may not be turning on. For example, your thermostat may need new batteries. Or, there could be an issue with the wires inside the thermostat. The thermostat may also be confused, in which case it may require a factory reset.

How do I fix an unresponsive thermostat?

If the thermostat is still unresponsive, make sure the breaker is shut off and remove the cover. If it looks dirty inside, use canned air or a soft artist brush to clean away accumulated grime that may be affecting its functionality. Then look for issues like loose wiring or terminal screws and tighten them up.

How do I know if my thermostat needs to be replaced?



9 Signs It’s Time to Replace Your Thermostat

  1. Your Thermostat Is Analog. …
  2. Your Thermostat Isn’t Programmable. …
  3. Your Thermostat Is Older than Ten Years. …
  4. Your HVAC Turns On and Off. …
  5. Your Energy Bills Are Unusually High. …
  6. Your Thermostat Gives Faulty Readings. …
  7. Your Thermostat Doesn’t Respond to Settings Changes.