Hello everyone!

When using a Parallel Compressors Rack System for several rooms at different temperatures I have seen EPR's (1 for each room) installed just before the rack's suction manifold to mantain the different room's pressures, and I have seen that Solenoid Valves are installed just after the liquid manifold (1 for each room) to cut refrigerant flow when set temperature is reached or when defrost is required.

Doesn't the EPR's should be enough to control temperature? Is it necessary to use Solenoid Valves?

Thanks in advanced!