The Hot Water Pipe was added in Update 5. They operate on a separate layer from the existing pipes, and can be overlaid without conflict. 

These work only when connected to a Hot Water Boiler, which also requires electricity, and they transport the hot water to radiators, shower heads and sinks.

When properly connected, you can connect hot water objects 47 squares away using Hot Water Pipe. It is worth noting that connecting to the water boiler with small pipes will shorten the distance the hot water will run.