API Energy^TM Expansion vessels are commonly used to protect closed water heating-cooling systems from being exposed to high pressure. Expansion vessels work by being part filled with air, this then protects the system by cushioning any shock which is caused by water hammer and also absorbing any excessive water pressure which may have been caused by thermal expansion.

HVAC Applications

In closed heating-cooling systems, the water expands or contracts as the system is heated up or cooled down respectively. Expansion vessels are used to compensate for the fluctuations in volume between maximum and minimum temperature within a permissible range.

API Energy^TM expansion vessels are used to maintain pressure in heating, cooling and solar power systems. . When the system heats up, the pressure rises with the result that expansion water flows from the external system into the water space. The pressurised cushion of air in the gas space is compressed and the pressure rises. When the system cools down and its pressure drops, this counter pressure pushes water in the membrane back into the external system. This releases the pressurised cushion of air in the gas space and lowers the pressure.

Water Supply Applications

Inline Intermediate Vessel is required with return temperatures > 70ºC at heating and solar systems and it is recommended at return temperatures < 0ºC at cooling systems, to be installed before the expansion vessel. In heating systems, connection to the intermediate vessel should be made from top.

In booster systems, vessels are used as buffer tanks to intermediately store the difference between the pumped volume flow and the volume flow actually needed. Vessels are also required to decrease the switching frequency of a pump and reduce peak loads.

Sanitary Hot Water Applications

When heating sanitary water, pressure rises as the water expands. In the worst case, the excess pressure is decreased by a safety valve, losing valuable heated potable water. The use of a API Energy^TM expansion vessel remedies this situation by preventing the unnecessary opening of the safety valve and providing for a more efficient, resource-conserving operation of the system.