What is a noted disadvantage of gravity hot water heating systems?

In gravity hot water heating systems, one noted disadvantage is the requirement for large pipe sizes to minimize flow resistance. This is due to the reliance on gravity for circulating water throughout the system, which means that the water must be able to flow freely without significant hindrances. When using larger pipe sizes, the flow of water becomes less impeded, allowing better movement due to gravity's natural force.

Using larger pipes can lead to increased material costs and more complicated construction considerations, as they require additional space and potentially more significant structural support. Moreover, the large diameter pipes also contribute to the weight and may affect the overall installation design, potentially raising challenges related to the routing and support of the piping system.

This need for larger pipes directly impacts the efficiency of the system by dictating the layout and the overall footprint of the installation, therefore marking a fundamental disadvantage of using a gravity hot water heating system.