GESTRA NRR2-50+T Steam Boiler Water Level Equipment 24Vdc The level controller NRR 2-50 / NRR 2-51 in conjunction with level electrodes NRG 2.-.. and level transmitter NRGT 26-1 is used as limit switch and water level controller, for instance in steam boilers, (pressurized) hot-water installations as well as condensate and feedwater tanks. The level controller indicates when the preset water level limit MIN or MAX is reached and opens or closes the control valve accordingly. The level controller is designed to be used with level electrodes NRG 21-.. and NRG 26-21 as well as the level transmitter NRGT 26-1. Please allow 2-3day delivery