The Walchem WDT400-14NU controller is now obsolete and the closest equivalent is the WCT600 controller. The new WCT600 series has upgraded features; for reference, here is the description of the old model:
Dual cooling tower controller, 120 VAC, prewired, single 4-20 mA output, no electrodes, integrated datalogging and config file import/export via USB flash stick.