7 day 2 channel programmer designed for control of heating and stored hot water in complete systems. It switches between central heating and stored hot water effortlessly, allowing both to function and be controlled independently of each other. This ensures the system operates in the most energy efficient way. Made and supported by Honeywell (Resideo), this unit is a direct replacement for the Honeywell ST9400C, it uses an industry standard wiring back box. Simply detach the old ST9400C from its backplate and clip in the Pro Controls 7 Day 2 Channel programmer. No additional wiring is required. The Honeywell ST699 and ST799 can also be updated using this unit for a fraction of the cost of trying to replace with discontinued old models with a simple wiring change.