What you should know
4-pipe: The 4 pipe system features two separate cooling and heating water coils, each with its own dedicated set of supply and return pipes and valves. This design allows for simultaneous cooling and heating.
2-pipe: The 2 pipe system consists of a single water coil connected to two pipes (supply and return) and one valve that allows for either cooling or heating, depending on the system’s mode. It cannot provide cooling and heating at the same time.
Wiring
4-pipe
Option 1
Two coils connected to two separate sets of pipes are installed (both hot and cold).
Two 2-position valves are required, with each controlled by a separate on/off signal (typically electric ball valves).
Option 2
Two coils connected to two separate sets of pipes are installed (both hot and cold).
Two valves are required, with each controlled by a single signal wire (typically normally-closed valves).
2-pipe
Option 1
One coil connected to one set of pipes is installed (either hot or cold).
One valve is required, which is controlled by a separate on/off signal (typically the electric ball valve).
Option 2
One coil connected to one set of pipes is installed (either hot or cold).
One valve is required, which is controlled by a single signal wire (typically the normally-closed valve).
