Sangamo Q551 Round Pattern Astro Zone 2 Time Switch - 3 Pin 20A

The Sangamo Q551 is a round pattern astro time switch designed for Zone 2 heating and lighting circuits, rated at 20A on 230V mains. The astro function automatically adjusts switching times based on sunrise and sunset throughout the year, eliminating the need to reprogram the unit for seasonal time changes. The 3-pin terminal layout connects to live, neutral and switched live outputs, suitable for controlling pumps, boilers, immersion heaters and outdoor lighting circuits.

Zone 2 time switches control secondary heating circuits such as upstairs radiators, conservatory heating zones or hot water cylinders that need different scheduling from the primary Zone 1 circuit. The Q551 programmes up to 24 hours of on/off operations, allowing multiple daily switching events to match occupancy patterns or off-peak electricity tariffs. The mechanical dial interface uses sliding pins to set on and off times, with each pin representing a 15-minute segment of the day.

The 100-hour battery reserve maintains programmed settings during mains power cuts without requiring reprogramming once power is restored. The round pattern casing measures 104mm diameter and 134mm depth, designed for surface mounting on walls or DIN rail installation inside distribution boards. The clear plastic cover allows the dial position and pin settings to be checked without removing the cover. Made in the UK by Sangamo, the Q551 carries a mechanical construction that provides reliable service in residential, commercial and light industrial Zone 2 applications.

Product Specification Sheet

Product Manual

What is Zone 2 used for?

Zone 2 refers to a secondary heating circuit controlled separately from the primary Zone 1 circuit. Common Zone 2 applications include upstairs radiators, conservatory heating, hot water cylinders or garage heating that need different switching times from the main living area.

How does the astro function work?

The astro function automatically adjusts switching times based on sunrise and sunset throughout the year. Once programmed, the unit compensates for seasonal changes in daylight hours without requiring manual reprogramming when clocks change or days lengthen in summer.

What does the 100-hour battery reserve do?

The battery reserve maintains programmed settings and clock time during mains power cuts for up to 100 hours. When power is restored, the time switch resumes normal operation without needing to be reprogrammed.

How is it mounted?

The Q551 can be surface-mounted on a wall using the rear fixing holes or installed on DIN rail inside a distribution board. The 104mm diameter round casing requires clearance for the 134mm depth including terminals and rear cover.