The LX H30-R1 3.0KW 1.5 inch Without Sensor Cable (Straight).
Sensor compatibility: Controlled by the system control box
Required flow rate: Set by a pressure switch, this switch will need to be pressurised, if it runs straight to a big bore outlet with no bends, there will be no back pressure and it may not work
Flow detection: Pressure switch built into the heater
This unit replaces the Rooster heater as they kept failing. This heater is longer than the Rooster so you may need to alter the plumbing slightly