Backflow and Thermal Expansion

Backflow and Thermal Expansion

What is Thermal Expansion? Thermal expansion is a phenomenon that happens when water is heated. When water is heated, it expands causing system pressure to increase. When these pressures aren’t alleviated, damages may occur within the piping distribution system.

In an open distribution system, excess heated water is distributed back through the water meter into the city main line.

However, in a closed water distribution system, the pressures may cause water piping to burst or water heater appliances to rupture. Examples of closed systems include water distribution systems with backflow preventers or pressure-reducing valves. Generally, municipal water systems have integral check valves (backflow preventers) inside the water meter. For this reason, thermal expansion must be alleviated. The most common method for thermal expansion control is the installation of a thermal expansion tank or valve. 

Do’s & Don’ts for Water Distribution Systems:

  • DO Remember to add backflow protection

  • DO Disconnect your water hose from the hose bibb during the winter

  • DO Add means for thermal expansion control

  • DON’T Submerge hose outlets

  • DON’T Plug or restrict the temperature and pressure relief valve on your water heater

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