What is a thermal expansion tank?

A thermal expansion tank is a crucial component of a hot water heating system. It is designed to accommodate the expansion of water in the system as it is heated, preventing excessive pressure buildup that can lead to leaks or damage to system components.

The tank is typically installed on the cold water supply line near the water heater. It consists of a sealed container with a bladder or diaphragm inside that separates the water from a cushion of air. As the water in the system heats up and expands, it pushes against the bladder, compressing the air and allowing the water to expand without creating excessive pressure.

Thermal expansion tanks are required by building codes in many jurisdictions to prevent the potentially dangerous increase in pressure that can occur in a closed hot water heating system. They are especially important in systems with check valves or backflow preventers, which can trap expanding water and lead to pressure spikes.

Regular maintenance and inspection of the thermal expansion tank are essential to ensure it is functioning properly and preventing excessive pressure buildup in the system. If you notice signs of leaking, corrosion, or loss of pressure in your hot water heating system, it may be time to have your thermal expansion tank checked by a qualified technician.