What is a common characteristic of hot water distribution pipes?

The correct answer highlights that hot water distribution pipes must have a pressure rating of at least 100 PSI at 180°F. This is crucial for ensuring that the pipes can withstand the conditions they will encounter in a hot water distribution system. High-temperature water increases the pressure within the pipes, and if the pipe material is not rated to handle this pressure, it could fail, leading to leaks or ruptures. This specific pressure rating is established to maintain safety and functionality in plumbing systems, especially when dealing with hot water applications.

The other options do not meet the necessary criteria for hot water distribution systems. For instance, requiring a pressure rating of only 85 PSI does not account for the high temperatures and resulting pressures that may be encountered. Furthermore, the type of solder used is critical in plumbing systems, particularly for hot water applications, where certain solders may not withstand high temperatures or might lead to failures. Installing pipes above freezing ground level is practical in many cases, but it does not directly pertain to the key characteristic of pressure ratings necessary for the safe operation of hot water distribution pipes.