If a backflow preventer is installed at the water meter, which component must be installed?

If a backflow preventer is installed at the water meter, which component must be installed?

• A. air chamber
• B. check valve
• C. pressure regulator
• D. expansion tank

Answer: (D)

When a backflow preventer is placed at the water meter, the house plumbing becomes a closed system. In a closed system, water can’t escape as it expands when heated, so pressure can rise to damaging levels. An expansion tank provides a dedicated space to absorb that extra volume and keep pressure from climbing too high, protecting the system and fixtures. Air chambers are older solutions that can fill with water and become ineffective, and a check valve or pressure regulator doesn’t address the issue of thermal expansion in a sealed loop.

When a backflow preventer is placed at the water meter, the house plumbing becomes a closed system. In a closed system, water can’t escape as it expands when heated, so pressure can rise to damaging levels. An expansion tank provides a dedicated space to absorb that extra volume and keep pressure from climbing too high, protecting the system and fixtures. Air chambers are older solutions that can fill with water and become ineffective, and a check valve or pressure regulator doesn’t address the issue of thermal expansion in a sealed loop.