There are a number of advantages of using a more modern closed heating/chilling system as opposed to a traditional open system with a feed and expansion tank. The water used in sealed systems is constantly being reused, as a result the dissolved air is taken care of and exposed steel in traditional vessels is not subject to continued corrosion. Closed systems also do not require heavy roof top tanks and the associated pipework; therefore water loss due to evaporation is greatly reduced.
Closed systems reduce installation cost. Their higher flow temperatures and greater temperature drops reduce the systems water circulation needs, enabling a smaller pump and pipes to be used. This combined with replacing the conventional header tank, associated pipework and lagging, leads to considerable savings.