Products Containing Mercury and the Environment including new State Laws & Regulations and pending legislation
Mercury is extremely harmful to the environment and cause severe health problems in humans and animals. For many years HVAC and HVAC Controls manufacturers have used mercury in switches. Mercury is a liquid metal and provides a good source used in many switches because of its fluidity and conductivity. From thermostats to boiler controls mercury provides a reliable and efficient switching mechanism to start and stop certain sequences in HVAC applications.
Because mercury is very harmful to the environment and because many people do not know it is harmful or they are irresponsible and improperly dispose of products containing mercury some States have come up with laws regulating products which contain mercury or there is pending legislation ban the sale and use of products which contain mercury. Manufacturers have alternative methods to control HVAC applications and have taken steps to decrease production of making products which contain mercury and increase production of replacement controls especially for the States where there is current or pending legislation.
It is important if you replace your thermostat to check to see if it has mercury before throwing it in the trash. If you see a little oval bulb with a silver liquid inside the bulb you have a thermostat which contains mercury. It is important to properly dispose of this part of your thermostat which contains mercury. Other HVAC controls which contain mercury are boiler controls especially on steam boiler systems. It is improbable that the typical homeowner or business owner will replace this control if it malfunctions but maintenance personnel and HVAC and boiler technicians should be aware of these new laws and the fact that mercury harms the environment so that they properly dispose of any product which contains mercury.
At the end of the usable life of a product which contains mercury the products which contain mercury must be recycled or disposed of in accordance with Local, State, and Federal Regulations so that the mercury in these products do not harm the environment.
Please refer to your individual state laws and regulations to determine specific requirements for disposal of any products containing mercury. Never put products which contain mercury in the trash. Call your local refuse or Disposal Company or the State Environmental Protection agency and ask how to properly dispose of products which contain mercury.
States with Current or Pending Legislation Banning the Sale or Distribution of Products which Contain Mercury*
| State | Effective Date |
| California | July 1, 2006 |
| Connecticut | July 1, 2004 |
| Illinois | July 1, 2007 |
| Louisiana | January 1, 2007 |
| Maine | July 1, 2006 |
| Massachusetts | May 1, 2008 |
| Minnesota | August 1, 2007 |
| New York | January 1, 2008 |
| Rhode Island | January 1, 2006 |
| Vermont | January 1, 2007 |
*If your State is not listed check you Local, State, and Federal regulations for laws pertaining to the sale, distribution, use, and disposal of products which contain mercury. Many state, local, and even private waste disposal facilities have special collection methods for products that contain mercury.
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There are two types of expansion tanks used on hot water 
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This domestic hot water mixing valve offers a way to temper the hot water coming from a hot water loop and 
This is a hot water economizer and is a big preheater for domestic hot water use. This boiler plant serves a large community for heating and domestic hot water use. Domestic hot water is used for showers, washing dishes, laundry, ect, ect, ect…. The cold water supply from the city is routed through the economizer to be pre-heated before it goes through a heat exchangerand then the hot water storage tank. This system saves money because it uses the exhaust gases from the boiler to pre-heat the city water supply which is normally 50 degrees Fahrenheit. The exhaust gases from the boiler would otherwise be vented to the atmosphere and would be considered wasted heat. 
