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Hot Water Time & Temperature addon (Electric Switch)

Included in the Hot Water Time & Temperature addon is the The Electric Switch and Temperature Probe, which is used to measure the temperature of the Hot Water Tank. The Electric Switch must be wired into a switched, fused  fused spur near the Hot Water tank. Place  Place the Temperature Probe into the pocket/under the insulation of the hot water tank. 

If the Hot Water Tank has an immersion heater backup, this can be wired into the Electric Switch (output) so you can also control the heating of the hot water from the immersion heater as well as the boiler. If the Electric Switch is wired into the immersion heater, it should be covered by the same switched, fused spur as the immersion heater. 


At no point should the Temperature Probe be pulled out or removed from the Electric Switch.

The Electric Switch should be wired into the same fused spur as the relevant zone valve or immersion heater.

  1. Always ensure that the boiler, immersion heater and wiring for the Electric Switch is electrically isolated before you commence work on any wiring.
  2. Locate the existing tank cylinder thermostat for the hot water tank. 
  3. If the same pocket as the cylinder stat is accessible, insert the Temperature Probe into this pocket.
    1. If it is not available, attach the Temperature Probe to the outside of the tank (under the insulation) using a thermal paste so it gets an accurate water temperature reading and has good adhesion.
  4. Break out the relevant section of a 1-gang pattress for the wiring, allowing for the temperature probe to exit the pattress box if applicable, and fix the pattress to the wall. It is recommended that a 40mm pattress is used.
  5. Pull through the relevant wiring, allowing plenty of spare.
  6. Wire in the Electric Switch as per the wiring diagrams provided, checking this is suitable as per the relevant installation manual, such as immersion heater.
  7. Remove the front cover of the Electric Switch to expose the screw holes. The cover can be removed by placing a flat bladed screwdriver into the gap underneath the Electric Switch and levering in a downwards direction.
  8. Fit the Electric Switch into the pattress, ensuring there are no trapped wires. Screw in using standard pattress screws, and check the unit is securely and safely attached to the wall.